Teosona

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Teosona Medicine

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Overdose

Capsule; Solution, ElixirSubstance-powder; Sustained-release tabletsCapsule, Extended ReleaseGeneral

The chronicity and pattern of theophylline overdosage significantly influences clinical manifestations of toxicity, management and outcome. There are two common presentations: (1) acute overdose, i.e., ingestion of a single large excessive dose ( > 10 mg/kg) as occurs in the context of an attempted suicide or isolated medication error, and (2) chronic overdosage, i.e., ingestion of repeated doses that are excessive for the patient's rate of theophylline clearance. The most common causes of chronic theophylline overdosage include patient or care giver error in dosing, clinician prescribing of an excessive dose or a normal dose in the presence of factors known to decrease the rate of theophylline clearance, and increasing the dose in response to an exacerbation of symptoms without first measuring the serum theophylline concentration to determine whether a dose increase is safe.

Severe toxicity from theophylline overdose is a relatively rare event. In one health maintenance organization, the frequency of hospital admissions for chronic overdosage of theophylline was about 1 per 1000 person-years exposure. In another study, among 6000 blood samples obtained for measurement of serum theophylline concentration, for any reason, from patients treated in an emergency department, 7% were in the 20-30 mcg/mL range and 3% were > 30 mcg/mL. Approximately two-thirds of the patients with serum theophylline concentrations in the 20-30 mcg/mL range had one or more manifestations of toxicity while > 90% of patients with serum theophylline concentrations > 30mcg/mL were clinically intoxicated. Similarly, in other reports, serious toxicity from theophylline is seen principally at serum concentrations > 30 mcg/mL.

Several studies have described the clinical manifestations of theophylline overdose and attempted to determine the factors that predict life-threatening toxicity. In general, patients who experience an acute overdose are less likely to experience seizures than patients who have experienced a chronic overdosage, unless the peak serum theophylline concentration is > 100 mcg/mL. After a chronic overdosage, generalized seizures, life-threatening cardiac arrhythmias, and death may occur at serum theophylline concentrations > 30 mcg/mL. The severity of toxicity after chronic overdosage is more strongly correlated with the patient's age than the peak serum theophylline concentration; patients > 60 years are at the greatest risk for severe toxicity and mortality after a chronic overdosage. Pre-existing or concurrent disease may also significantly increase the susceptibility of a patient to a particular toxic manifestation, e.g., patients with neurologic disorders have an increased risk of seizures and patients with cardiac disease have an increased risk of cardiac arrhythmias for a given serum theophylline concentration compared to patients without the underlying disease.

The frequency of various reported manifestations of theophylline overdose according to the mode of overdose are listed in Table IV.

Other manifestations of theophylline toxicity include increases in serum calcium, creatine kinase, myoglobin and leukocyte count, decreases in serum phosphate and magnesium, acute myocardial infarction, and urinary retention in men with obstructive uropathy.

Seizures associated with serum theophylline concentrations > 30 mcg/mL are often resistant to anticonvulsant therapy and may result in irreversible brain injury if not rapidly controlled. Death from theophylline toxicity is most often secondary to cardiorespiratory arrest and/or hypoxic encephalopathy following prolonged generalized seizures or intractable cardiac arrhythmias causing hemodynamic compromise.

Overdose Management General Recommendations for Patients with Symptoms of Theophylline Overdose or Serum

Theophylline Concentrations > 30 mcg/mL (Note: Serum theophylline concentrations may continue to increase after presentation of the patient for medical care.)

  1. While simultaneously instituting treatment, contact a regional poison center to obtain updated information and advice on individualizing the recommendations that follow.
  2. Institute supportive care, including establishment of intravenous access, maintenance of the airway, and electrocardiographic monitoring.
  3. Treatment of seizures Because of the high morbidity and mortality associated with theophyllineinduced seizures, treatment should be rapid and aggressive. Anticonvulsant therapy should be initiated with an intravenous benzodiazepine, e.g., diazepam, in increments of 0.1-0.2 mg/kg every 1-3 minutes until seizures are terminated. Repetitive seizures should be treated with a loading dose of phenobarbital (20 mg/kg infused over 30- 60 minutes). Case reports of theophylline overdose in humans and animal studies suggest that phenytoin is ineffective in terminating theophylline-induced seizures. The doses of benzodiazepines and phenobarbital required to terminate theophyllineinduced seizures are close to the doses that may cause severe respiratory depression or respiratory arrest; the clinician should therefore be prepared to provide assisted ventilation. Elderly patients and patients with COPD may be more susceptible to the respiratory depressant effects of anticonvulsants. Barbiturate-induced coma or administration of general anesthesia may be required to terminate repetitive seizures or status epilepticus. General anesthesia should be used with caution in patients with theophylline overdose because fluorinated volatile anesthetics may sensitize the myocardium to endogenous catecholamines released by theophylline. Enflurane appears to less likely to be associated with this effect than halothane and may, therefore, be safer. Neuromuscular blocking agents alone should not be used to terminate seizures since they abolish the musculoskeletal manifestations without terminating seizure activity in the brain.
  4. Anticipate Need for Anticonvulsants In patients with theophylline overdose who are at high risk for theophylline induced seizures, e.g., patients with acute overdoses and serum theophylline concentrations > 100 mcg/mL chronic overdosage in patients > 60 years of age with serum theophylline concentrations > 30 mcg/mL, the need for anticonvulsant therapy should be anticipated. A benzodiazepine such as diazepam should be drawn into a syringe and kept at the patient's bedside and medical personnel qualified to treat seizures should be immediately available. In selected patients at high risk for theophylline-induced seizures, consideration should be given to the administration of prophylactic anticonvulsant therapy. Situations where prophylactic anticonvulsant therapy should be considered in high risk patients include anticipated delays in instituting methods for extracorporeal removal of theophylline (e.g., transfer of a high risk patient from one health care facility to another for extracorporeal removal) and clinical circumstances that significantly interfere with efforts to enhance theophylline clearance (e.g., a neonate where dialysis may not be technically feasible or a patient with vomiting unresponsive to antiemetics who is unable to tolerate multipledose oral activated charcoal). In animal studies, prophylactic administration of phenobarbital, but not phenytoin, has been shown to delay the onset of theophylline induced generalized seizures and to increase the dose of theophylline required to induce seizures (i.e., markedly increases the LD50). Although there are no controlled studies in humans, a loading dose of intravenous phenobarbital (20 mg/kg infused over 60 minutes) may delay or prevent life-threatening seizures in high risk patients while efforts to enhance theophylline clearance are continued. Phenobarbital may cause respiratory depression, particularly in elderly patients and patients with COPD.
  5. Treatment of cardiac arrhythmias Sinus tachycardia and simple ventricular premature beats are not harbingers of life-threatening arrhythmias, they do not require treatment in the absence of hemodynamic compromise, and they resolve with declining serum theophylline concentrations. Other arrhythmias, especially those associated with hemodynamic compromise, should be treated with antiarrhythmic therapy appropriate for the type of arrhythmia.
  6. Gastrointestinal decontamination Oral activated charcoal (0.5 g/kg up to 20 g and repeat at least once 1-2 hours after the first dose) is extremely effective in blocking the absorption of theophylline throughout the gastrointestinal tract, even when administered several hours after ingestion. If the patient is vomiting, the charcoal should be administered through a nasogastric tube or after administration of an antiemetic. Phenothiazine antiemetics such as prochlorperazine or perphenazine should be avoided since they can lower the seizure threshold and frequently cause dystonic reactions. A single dose of sorbitol may be used to promote stooling to facilitate removal of theophylline bound to charcoal from the gastrointestinal tract. Sorbitol, however, should be dosed with caution since it is a potent purgative which can cause profound fluid and electrolyte abnormalities, particularly after multiple doses. Commercially available fixed combinations of liquid charcoal and sorbitol should be avoided in young children and after the first dose in adolescents and adults since they do not allow for individualization of charcoal and sorbitol dosing. Ipecac syrup should be avoided in theophylline overdoses. Although ipecac induces emesis, it does not reduce the absorption of theophylline unless administered within 5 minutes of ingestion and even then is less effective than oral activated charcoal. Moreover, ipecac induced emesis may persist for several hours after a single dose and significantly decrease the retention and the effectiveness of oral activated charcoal.
  7. Serum Theophylline Concentration Monitoring The serum theophylline concentration should be measured immediately upon presentation, 2-4 hours later, and then at sufficient intervals, e.g., every 4 hours, to guide treatment decisions and to assess the effectiveness of therapy. Serum theophylline concentrations may continue to increase after presentation of the patient for medical care as a result of continued absorption of theophylline from the gastrointestinal tract. Serial monitoring of serum theophylline serum concentrations should be continued until it is clear that the concentration is no longer rising and has returned to non-toxic levels.
  8. General Monitoring Procedures Electrocardiographic monitoring should be initiated on presentation and continued until the serum theophylline level has returned to a non-toxic level. Serum electrolytes and glucose should be measured on presentation and at appropriate intervals indicated by clinical circumstances. Fluid and electrolyte abnormalities should be promptly corrected. Monitoring and treatment should be continued until the serum concentration decreases below 20 mcg/mL.
  9. Enhance clearance of theophylline Multiple-dose oral activated charcoal (e.g., 0.5 mg/kg up to 20 g, every two hours) increases the clearance of theophylline at least twofold by adsorption of theophylline secreted into gastrointestinal fluids. Charcoal must be retained in, and pass through, the gastrointestinal tract to be effective; emesis should therefore be controlled by administration of appropriate antiemetics. Alternatively, the charcoal can be administered continuously through a nasogastric tube in conjunction with appropriate antiemetics. A single dose of sorbitol may be administered with the activated charcoal to promote stooling to facilitate clearance of the adsorbed theophylline from the gastrointestinal tract. Sorbitol alone does not enhance clearance of theophylline and should be dosed with caution to prevent excessive stooling which can result in severe fluid and electrolyte imbalances. Commercially available fixed combinations of liquid charcoal and sorbitol should be avoided in young children and after the first dose in adolescents and adults since they do not allow for individualization of charcoal and sorbitol dosing. In patients with intractable vomiting, extracorporeal methods of theophylline removal should be instituted (see OVERDOSAGE, Extracorporeal Removal).
Specific Recommendations

Acute Overdose

  1. Serum Concentration > 20 < 30 mcg/mL
    1. Administer a single dose of oral activated charcoal.
    2. Monitor the patient and obtain a serum theophylline concentration in 2-4 hours to insure that the concentration is not increasing.
  2. Serum Concentration > 30 < 100 mcg/mL
    1. Administer multiple dose oral activated charcoal and measures to control emesis.
    2. Monitor the patient and obtain serial theophylline concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
    3. Institute extracorporeal removal if emesis, seizures, or cardiac arrhythmias cannot be adequately controlled (see OVERDOSAGE, Extracorporeal Removal).
  3. Serum Concentration > 100 mcg/mL
    1. Consider prophylactic anticonvulsant therapy.
    2. Administer multiple-dose oral activated charcoal and measures to control emesis.
    3. Consider extracorporeal removal, even if the patient has not experienced a seizure (see OVERDOSAGE, Extracorporeal Removal).
    4. Monitor the patient and obtain serial theophylline concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
Chronic Overdosage
  1. Serum Concentration > 20 < 30 mcg/mL (with manifestations of theophylline toxicity)
    1. Administer a single dose of oral activated charcoal.
    2. Monitor the patient and obtain a serum theophylline concentration in 2-4 hours to insure that the concentration is not increasing.
  2. Serum Concentration > 30 mcg/mL in patients < 60 years of age
    1. Administer multiple-dose oral activated charcoal and measures to control emesis.
    2. Monitor the patient and obtain serial theophylline concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
    3. Institute extracorporeal removal if emesis, seizures, or cardiac arrhythmias cannot be adequately controlled (see OVERDOSAGE, Extracorporeal Removal).
  3. Serum Concentration > 30 mcg/mL in patients ≥ 60 years of age.
    1. Consider prophylactic anticonvulsant therapy.
    2. Administer multiple-dose oral activated charcoal and measures to control emesis.
    3. Consider extracorporeal removal even if the patient has not experienced a seizure (see OVERDOSAGE, Extracorporeal Removal).
    4. Monitor the patient and obtain serial theophylline concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
Extracorporeal Removal

Increasing the rate of theophylline clearance by extracorporeal methods may rapidly decrease serum concentrations, but the risks of the procedure must be weighed against the potential benefit. Charcoal hemoperfusion is the most effective method of extracorporeal removal, increasing theophylline clearance up to six fold, but serious complications, including hypotension, hypocalcemia, platelet consumption and bleeding diatheses may occur. Hemodialysis is about as efficient as multiple-dose oral activated charcoal and has a lower risk of serious complications than charcoal hemoperfusion. Hemodialysis should be considered as an alternative when charcoal hemoperfusion is not feasible and multiple-dose oral charcoal is ineffective because of intractable emesis. Serum theophylline concentrations may rebound 5-10 mcg/mL after discontinuation of charcoal hemoperfusion or hemodialysis due to redistribution of theophylline from the tissue compartment. Peritoneal dialysis is ineffective for theophylline removal; exchange transfusions in neonates have been minimally effective.

General

The chronicity and pattern of Teosona overdosage significantly influences clinical manifestations of toxicity, management and outcome. There are two common presentations: (1) acute overdose, i.e., infusion of an excessive loading dose or excessive maintenance infusion rate for less than 24 hours, and (2) chronic overdosage, i.e., excessive maintenance infusion rate for greater than 24 hours. The most common causes of chronic Teosona overdosage include clinician prescribing of an excessive dose or a normal dose in the presence of factors known to decrease the rate of Teosona clearance and increasing the dose in response to an exacerbation of symptoms without first measuring the serum Teosona concentration to determine whether a dose increase is safe.

Several studies have described the clinical manifestations of Teosona overdose following oral administration and attempted to determine the factors that predict life-threatening toxicity. In general, patients who experience an acute overdose are less likely to experience seizures than patients who have experienced a chronic overdosage, unless the peak serum Teosona concentration is > 100 mcg/mL. After a chronic overdosage, generalized seizures, life-threatening cardiac arrhythmias, and death may occur at serum Teosona concentrations > 30 mcg/mL. The severity of toxicity after chronic overdosage is more strongly correlated with the patient's age than the peak serum Teosona concentration; patients > 60 years are at the greatest risk for severe toxicity and mortality after a chronic overdosage. Pre-existing or concurrent disease may also significantly increase the susceptibility of a patient to a particular toxic manifestation, e.g., patients with neurologic disorders have an increased risk of seizures and patients with cardiac disease have an increased risk of cardiac arrhythmias for a given serum Teosonaconcentration compared to patients without the underlying disease.

The frequency of various reported manifestations of oral Teosona overdose according to the mode of overdose are listed in Table IV.

Other manifestations of Teosona toxicity include increases in serum calcium, creatine kinase, myoglobin and leukocyte count, decreases in serum phosphate and magnesium, acute myocardial infarction, and urinary retention in men with obstructive uropathy. Hypercalcemia has been reported in a patient with hyperthyroid disease at therapeutic Teosona concentrations.

Seizures associated with serum Teosona concentrations > 30 mcg/mL are often resistant to anticonvulsant therapy and may result in irreversible brain injury if not rapidly controlled. Death from Teosona toxicity is most often secondary to cardiorespiratory arrest and/or hypoxic encephalopathy following prolonged generalized seizures or intractable cardiac arrhythmias causing hemodynamic compromise.

Overdose Management

General Recommendations for Patients with Symptoms of Teosona Overdose or Serum Teosona Concentrations > 30 mcg/mL while receiving intravenous Teosona.

  1. Stop the Teosona infusion.
  2. While simultaneously instituting treatment, contact a regional poison center to obtain updated information and advice on individualizing the recommendations that follow.
  3. Institute supportive care, including establishment of intravenous access, maintenance of the airway, and electrocardiographic monitoring.
  4. Treatment of seizures. Because of the high morbidity and mortality associated with Teosona-induced seizures, treatment should be rapid and aggressive. Anticonvulsant therapy should be initiated with an intravenous benzodiazepine, e.g., diazepam, in increments of 0.1-0.2 mg/kg every 1-3 minutes until seizures are terminated. Repetitive seizures should be treated with a loading dose of phenobarbital (20 mg/kg infused over 30-60 minutes). Case reports of Teosona overdose in humans and animal studies suggest that phenytoin is ineffective in terminating Teosona-induced seizures. The doses of benzodiazepines and phenobarbital required to terminate Teosona-induced seizures are close to the doses that may cause severe respiratory depression or respiratory arrest; the clinician should therefore be prepared to provide assisted ventilation. Elderly patients and patients with COPD may be more susceptible to the respiratory depressant effects of anticonvulsants. Barbiturate-induced coma or administration of general anesthesia may be required to terminate repetitive seizures or status epilepticus. General anesthesia should be used with caution in patients with Teosona overdose because fluorinated volatile anesthetics may sensitize the myocardium to endogenous catecholamines released by Teosona. Enflurane appears less likely to be associated with this effect than halothane and may, therefore, be safer. Neuromuscular blocking agents alone should not be used to terminate seizures since they abolish the musculoskeletal manifestations without terminating seizure activity in the brain.
  5. Anticipate Need for Anticonvulsants. In patients with Teosona overdose who are at high risk for Teosona-induced seizures, e.g., patients with acute overdoses and serum Teosona concentrations > 100 mcg/mL or chronic overdosage in patients > 60 years of age with serum Teosona concentrations > 30 mcg/mL, the need for anticonvulsant therapy should be anticipated. A benzodiazepine such as diazepam should be drawn into a syringe and kept at the patient's bedside and medical personnel qualified to treat seizures should be immediately available. In selected patients at high risk for Teosona-induced seizures, consideration should be given to the administration of prophylactic anticonvulsant therapy. Situations where prophylactic anticonvulsant therapy should be considered in high risk patients include anticipated delays in instituting methods for extracorporeal removal of Teosona (e.g., transfer of a high risk patient from one health care facility to another for extracorporeal removal) and clinical circumstances that significantly interfere with efforts to enhance Teosona clearance (e.g., a neonate where dialysis may not be technically feasible or a patient with vomiting unresponsive to antiemetics who is unable to tolerate multiple-dose oral activated charcoal). In animal studies, prophylactic administration of phenobarbital, but not phenytoin, has been shown to delay the onset of Teosonainduced generalized seizures and to increase the dose of Teosona required to induce seizures (i.e., markedly increases the LD50). Although there are no controlled studies in humans, a loading dose of intravenous phenobarbital (20 mg/kg infused over 60 minutes) may delay or prevent life-threatening seizures in high risk patients while efforts to enhance Teosona clearance are continued. Phenobarbital may cause respiratory depression, particularly in elderly patients and patients with COPD.
  6. Treatment of cardiac arrhythmias.Sinus tachycardia and simple ventricular premature beats are not harbingers of life-threatening arrhythmias, they do not require treatment in the absence of hemodynamic compromise, and they resolve with declining serum Teosona concentrations. Other arrhythmias, especially those associated with hemodynamic compromise, should be treated with antiarrhythmic therapy appropriate for the type of arrhythmia.
  7. Serum Teosona Concentration Monitoring. The serum Teosona concentration should be measured immediately upon presentation, 2-4 hours later, and then at sufficient intervals, e.g., every 4 hours, to guide treatment decisions and to assess the effectiveness of therapy. Serum Teosona concentrations may continue to increase after presentation of the patient for medical care as a result of continued absorption of Teosona from the gastrointestinal tract. Serial monitoring of Teosona serum concentrations should be continued until it is clear that the concentration is no longer rising and has returned to non-toxic levels.
  8. General Monitoring Procedures. Electrocardiographic monitoring should be initiated on presentation and continued until the serum Teosona level has returned to a non-toxic level. Serum electrolytes and glucose should be measured on presentation and at appropriate intervals indicated by clinical circumstances. Fluid and electrolyte abnormalities should be promptly corrected. Monitoring and treatment should be continued until the serum concentration decreases below 20 mcg/mL.
  9. Enhance clearance of Teosona. Multiple-dose oral activated charcoal (e.g., 0.5 mg/kg up to 20 g every two hours) increases the clearance of Teosona at least twofold by adsorption of Teosona secreted into gastrointestinal fluids. Charcoal must be retained in, and pass through, the gastrointestinal tract to be effective; emesis should therefore be controlled by administration of appropriate antiemetics. Alternatively, the charcoal can be administered continuously through a nasogastric tube in conjunction with appropriate antiemetics. A single dose of sorbitol may be administered with the activated charcoal to promote stooling to facilitate clearance of the adsorbed Teosona from the gastrointestinal tract. Sorbitol alone does not enhance clearance of Teosona and should be dosed with caution to prevent excessive stooling which can result in severe fluid and electrolyte imbalances. Commercially available fixed combinations of liquid charcoal and sorbitol should be avoided in young children and after the first dose in adolescents and adults since they do not allow for individualization of charcoal and sorbitol dosing. In patients with intractable vomiting, extracorporeal methods of Teosona removal should be instituted (see OVERDOSAGE, Extracorporeal Removal).
Specific Recommendations Acute Overdose (e.g., excessive loading dose or excessive infusion rate for < 24 hours)
  1. Serum Concentration > 20 < 30 mcg/mL
    1. Stop the Teosona infusion.
    2. Monitor the patient and obtain a serum Teosona concentration in 2-4 hours to insure that the concentration is decreasing.
  2. Serum Concentration > 30 < 100 mcg/mL
    1. Stop the Teosona infusion.
    2. Administer multiple dose oral activated charcoal and measures to control emesis.
    3. Monitor the patient and obtain serial Teosona concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
    4. Institute extracorporeal removal if emesis, seizures, or cardiac arrhythmias cannot be adequately controlled (see OVERDOSAGE, Extracorporeal Removal).
  3. Serum Concentration > 100 mcg/mL
    1. Stop the Teosona infusion.
    2. Consider prophylactic anticonvulsant therapy.
    3. Administer multiple-dose oral activated charcoal and measures to control emesis.
    4. Consider extracorporeal removal, even if the patient has not experienced a seizure (see OVERDOSAGE, Extracorporeal Removal).
    5. Monitor the patient and obtain serial Teosona concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
Chronic Overdosage (e.g., excessive infusion rate for greater than 24 hours)
  1. Serum Concentration > 20 < 30 mcg/mL (with manifestations of Teosona toxicity)
    1. Stop the Teosona infusion.
    2. Monitor the patient and obtain a serum Teosona concentration in 2-4 hours to insure that the concentration is decreasing.
  2. Serum Concentration > 30 mcg/mL in patients < 60 years of age
    1. Stop the Teosona infusion.
    2. Administer multiple-dose oral activated charcoal and measures to control emesis.
    3. Monitor the patient and obtain serial Teosona concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
    4. Institute extracorporeal removal if emesis, seizures, or cardiac arrhythmias cannot be adequately controlled (see OVERDOSAGE, Extracorporeal Removal).
  3. Serum Concentration > 30 mcg/mL in patients ≥ 60 years of age
    1. Stop the Teosona infusion.
    2. Consider prophylactic anticonvulsant therapy.
    3. Administer multiple-dose oral activated charcoal and measures to control emesis.
    4. Consider extracorporeal removal even if the patient has not experienced a seizure (see OVERDOSAGE, Extracorporeal Removal).
    5. Monitor the patient and obtain serial Teosona concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
Extracorporeal Removal

Increasing the rate of Teosona clearance by extracorporeal methods may rapidly decrease serum concentrations, but the risks of the procedure must be weighed against the potential benefit. Charcoal hemoperfusion is the most effective method of extracorporeal removal, increasing Teosona clearance up to six fold, but serious complications, including hypotension, hypocalcemia, platelet consumption and bleeding diatheses may occur. Hemodialysis is about as efficient as multiple-dose oral activated charcoal and has a lower risk of serious complications than charcoal hemoperfusion. Hemodialysis should be considered as an alternative when charcoal hemoperfusion is not feasible and multiple-dose oral charcoal is ineffective because of intractable emesis. Serum Teosona concentrations may rebound 5-10 mcg/mL after discontinuation of charcoal hemoperfusion or hemodialysis due to redistribution of Teosona from the tissue compartment. Peritoneal dialysis is ineffective for Teosona removal; exchange transfusions in neonates have been minimally effective.

General

The chronicity and pattern of theophylline overdosage significantly influences clinical manifestations of toxicity, management and outcome. There are two common presentations: (1) acute overdose, i.e., ingestion of a single large excessive dose ( > 10 mg/kg) as occurs in the context of an attempted suicide or isolated medication error, and (2) chronic overdosage, i.e., ingestion of repeated doses that are excessive for the patient's rate of theophylline clearance. The most common causes of chronic theophylline overdosage include patient or care giver error in dosing, healthcare professional prescribing of an excessive dose or a normal dose in the presence of factors known to decrease the rate of theophylline clearance, and increasing the dose in response to an exacerbation of symptoms without first measuring the serum theophylline concentration to determine whether a dose increase is safe.

Severe toxicity from theophylline overdose is a relatively rare event. In one health maintenance organization, the frequency of hospital admissions for chronic overdosage of theophylline was about 1 per 1000 person-years exposure. In another study, among 6000 blood samples obtained for measurement of serum theophylline concentration, for any reason, from patients treated in an emergency department, 7% were in the 20-30 mcg/mL range and 3% were > 30 mcg/mL. Approximately two-thirds of the patients with serum theophylline concentrations in the 20-30 mcg/mL range had one or more manifestations of toxicity while > 90% of patients with serum theophylline concentrations > 30 mcg/mL were clinically intoxicated. Similarly, in other reports, serious toxicity from theophylline is seen principally at serum concentrations > 30 mcg/mL.

Several studies have described the clinical manifestations of theophylline overdose and attempted to determine the factors that predict life-threatening toxicity. In general, patients who experience an acute overdose are less likely to experience seizures than patients who have experienced a chronic overdosage, unless the peak serum theophylline concentration is > 100 mcg/mL. After a chronic overdosage, generalized seizures, life-threatening cardiac arrhythmias, and death may occur at serum theophylline concentrations > 30 mcg/mL. The severity of toxicity after chronic overdosage is more strongly correlated with the patient's age than the peak serum theophylline concentration; patients > 60 years are at the greatest risk for severe toxicity and mortality after a chronic overdosage. Pre-existing or concurrent disease may also significantly increase the susceptibility of a patient to a particular toxic manifestation, e.g., patients with neurologic disorders have an increased risk of seizures and patients with cardiac disease have an increased risk of cardiac arrhythmias for a given serum theophylline concentration compared to patients without the underlying disease.

The frequency of various reported manifestations of theophylline overdose according to the mode of overdose are listed in Table IV.

Other manifestations of theophylline toxicity include increases in serum calcium, creatine kinase, myoglobin and leukocyte count, decreases in serum phosphate and magnesium, acute myocardial infarction, and urinary retention in men with obstructive uropathy. Seizures associated with serum theophylline concentrations > 30 mcg/mL are often resistant to anticonvulsant therapy and may result in irreversible brain injury if not rapidly controlled. Death from theophylline toxicity is most often secondary to cardiorespiratory arrest and/or hypoxic encephalopathy following prolonged generalized seizures or intractable cardiac arrhythmias causing hemodynamic compromise.

Overdose Management

General Recommendations for Patients with Symptoms of Theophylline Overdose or Serum Theophylline Concentrations > 30 mcg/mL (Note: Serum theophylline concentrations may continue to increase after presentation of the patient for medical care.)

  1. While simultaneously instituting treatment, contact a regional poison center to obtain updated information and advice on individualizing the recommendations that follow.
  2. Institute supportive care, including establishment of intravenous access, maintenance of the airway, and electrocardiographic monitorin
  3. Treatment of seizures. Because of the high morbidity and mortality associated with theophylline-induced seizures, treatment should be rapid and aggressive. Anticonvulsant therapy should be initiated with an intravenous benzodiazepine, e.g., diazepam, in increments of 0.1-0.2 mg/kg every 1-3 minutes until seizures are terminated. Repetitive seizures should be treated with a loading dose of phenobarbital (20 mg/kg infused over 30-60 minutes). Case reports of theophylline overdose in humans and animal studies suggest that phenytoin is ineffective in terminating theophylline-induced seizures. The doses of benzodiazepines and phenobarbital required to terminate theophylline-induced seizures are close to the doses that may cause severe respiratory depression or respiratory arrest; the healthcare professional should therefore be prepared to provide assisted ventilation. Elderly patients and patients with COPD may be more susceptible to the respiratory depressant effects of anticonvulsants. Barbiturate-induced coma or administration of general anesthesia may be required to terminate repetitive seizures or status epilepticus. General anesthesia should be used with caution in patients with theophylline overdose because fluorinated volatile anesthetics may sensitize the myocardium to endogenous catecholamines released by theophylline. Enflurane appears less likely to be associated with this effect than halothane and may, therefore, be safer. Neuromuscular blocking agents alone should not be used to terminate seizures since they abolish the musculoskeletal manifestations without terminating seizure activity in the brain.
  4. Anticipate need for anticonvulsants. In patients with theophylline overdose who are at high risk for theophylline-induced seizures, e.g., patients with acute overdoses and serum theophylline concentrations > 100 mcg/mL or chronic overdosage in patients > 60 years of age with serum theophylline concentrations > 30 mcg/mL, the need for anticonvulsant therapy should be anticipated. A benzodiazepine such as diazepam should be drawn into a syringe and kept at the patient's bedside and medical personnel qualified to treat seizures should be immediately available. In selected patients at high risk for theophylline-induced seizures, consideration should be given to the administration of prophylactic anticonvulsant therapy. Situations where prophylactic anticonvulsant therapy should be considered in high risk patients include anticipated delays in instituting methods for extracorporeal removal of theophylline (e.g., transfer of a high risk patient from one health care facility to another for extracorporeal removal) and clinical circumstances that significantly interfere with efforts to enhance theophylline clearance (e.g., a neonate where dialysis may not be technically feasible or a patient with vomiting unresponsive to antiemetics who is unable to tolerate multiple-dose oral activated charcoal). In animal studies, prophylactic administration of phenobarbital, but not phenytoin, has been shown to delay the onset of theophylline-induced generalized seizures and to increase the dose of theophylline required to induce seizures (i.e., markedly increases the LD50). Although there are no controlled studies in humans, a loading dose of intravenous phenobarbital (20 mg/kg infused over 60 minutes) may delay or prevent life-threatening seizures in high risk patients while efforts to enhance theophylline clearance are continued. Phenobarbital may cause respiratory depression, particularly in elderly patients and patients with COPD.
  5. Treatment of cardiac arrhythmias. Sinus tachycardia and simple ventricular premature beats are not harbingers of life-threatening arrhythmias, they do not require treatment in the absence of hemodynamic compromise, and they resolve with declining serum theophylline concentrations. Other arrhythmias, especially those associated with hemodynamic compromise, should be treated with antiarrhythmic therapy appropriate for the type of arrhythmia.
  6. Gastrointestinal decontamination. Oral activated charcoal (0.5 g/kg up to 20 g and repeat at least once 1-2 hours after the first dose) is extremely effective in blocking the absorption of theophylline throughout the gastrointestinal tract, even when administered several hours after ingestion. If the patient is vomiting, the charcoal should be administered through a nasogastric tube or after administration of an antiemetic. Phenothiazine antiemetics such as prochlorperazine or perphenazine should be avoided since they can lower the seizure threshold and frequently cause dystonic reactions. A single dose of sorbitol may be used to promote stooling to facilitate removal of theophylline bound to charcoal from the gastrointestinal tract. Sorbitol, however, should be dosed with caution since it is a potent purgative which can cause profound fluid and electrolyte abnormalities, particularly after multiple doses. Commercially available fixed combinations of liquid charcoal and sorbitol should be avoided in young children and after the first dose in adolescents and adults since they do not allow for individualization of charcoal and sorbitol dosing. Ipecac syrup should be avoided in theophylline overdoses. Although ipecac induces emesis, it does not reduce the absorption of theophylline unless administered within 5 minutes of ingestion and even then is less effective than oral activated charcoal. Moreover, ipecac induced emesis may persist for several hours after a single dose and significantly decrease the retention and the effectiveness of oral activated charcoal.
  7. Serum theophylline concentration monitoring. The serum theophylline concentration should be measured immediately upon presentation, 2-4 hours later, and then at sufficient intervals, e.g., every 4 hours, to guide treatment decisions and to assess the effectiveness of therapy. Serum theophylline concentrations may continue to increase after presentation of the patient for medical care as a result of continued absorption of theophylline from the gastrointestinal tract. Serial monitoring of serum theophylline concentrations should be continued until it is clear that the concentration is no longer rising and has returned to non-toxic levels.
  8. General monitoring procedures. Electrocardiographic monitoring should be initiated on presentation and continued until the serum theophylline level has returned to a non-toxic level. Serum electrolytes and glucose should be measured on presentation and at appropriate intervals indicated by clinical circumstances. Fluid and electrolyte abnormalities should be promptly corrected. Monitoring and treatment should be continued until the serum concentration decreases below 20 mcg/mL.
  9. Enhance clearance of theophylline. Multiple-dose oral activated charcoal (e.g., 0.5 g/kg up to 20 g, every two hours) increases the clearance of theophylline at least twofold by adsorption of theophylline secreted into gastrointestinal fluids. Charcoal must be retained in, and pass through, the gastrointestinal tract to be effective; emesis should therefore be controlled by administration of appropriate antiemetics. Alternatively, the charcoal can be administered continuously through a nasogastric tube in conjunction with appropriate antiemetics. A single dose of sorbitol may be administered with the activated charcoal to promote stooling to facilitate clearance of the adsorbed theophylline from the gastrointestinal tract. Sorbitol alone does not enhance clearance of theophylline and should be dosed with caution to prevent excessive stooling which can result in severe fluid and electrolyte imbalances. Commercially available fixed combinations of liquid charcoal and sorbitol should be avoided in young children and after the first dose in adolescents and adults since they do not allow for individualization of charcoal and sorbitol dosing. In patients with intractable vomiting, extracorporeal methods of theophylline removal should be instituted (see OVERDOSAGE, Extracorporeal Removal).
Specific Recommendations Acute Overdose
  1. Serum Concentration > 20 < 30 mcg/mL
    1. Administer a single dose of oral activated charcoal.
    2. Monitor the patient and obtain a serum theophylline concentration in 2-4 hours to insure that the concentration is not increasing.
  2. Serum Concentration > 30 < 100 mcg/mL
    1. Administer multiple dose oral activated charcoal and measures to control emesis.
    2. Monitor the patient and obtain serial theophylline concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
    3. Institute extracorporeal removal if emesis, seizures, or cardiac arrhythmias cannot be adequately controlled (see OVERDOSAGE, Extracorporeal Removal).
  3. Serum Concentration > 100 mcg/mL
    1. Consider prophylactic anticonvulsant therapy.
    2. Administer multiple-dose oral activated charcoal and measures to control emesis.
    3. Consider extracorporeal removal, even if the patient has not experienced a seizure (see OVERDOSAGE, Extracorporeal Removal).
    4. Monitor the patient and obtain serial theophylline concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
Chronic Overdosage
  1. Serum Concentration > 20 < 30 mcg/mL (with manifestations of theophylline toxicity)
    1. Administer a single dose of oral activated charcoal.
    2. Monitor the patient and obtain a serum theophylline concentration in 2-4 hours to insure that the concentration is not increasing.
  2. Serum Concentration > 30 mcg/mL in patients < 60 years of age
    1. Administer multiple-dose oral activated charcoal and measures to control emesis.
    2. Monitor the patient and obtain serial theophylline concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
    3. Institute extracorporeal removal if emesis, seizures, or cardiac arrhythmias cannot be adequately controlled (see OVERDOSAGE, Extracorporeal Removal).
  3. Serum Concentration > 30 mcg/mL in patients ³ 60 years of age.
    1. Consider prophylactic anticonvulsant therapy.
    2. Administer multiple-dose oral activated charcoal and measures to control emesis.
    3. Consider extracorporeal removal even if the patient has not experienced a seizure (see OVERDOSAGE, Extracorporeal Removal).
    4. Monitor the patient and obtain serial theophylline concentrations every 2-4 hours to gauge the effectiveness of therapy and to guide further treatment decisions.
Extracorporeal Removal

Increasing the rate of theophylline clearance by extracorporeal methods may rapidly decrease serum concentrations, but the risks of the procedure must be weighed against the potential benefit. Charcoal hemoperfusion is the most effective method of extracorporeal removal, increasing theophylline clearance up to six fold, but serious complications, including hypotension, hypocalcemia, platelet consumption and bleeding diatheses may occur. Hemodialysis is about as efficient as multiple-dose oral activated charcoal and has a lower risk of serious complications than charcoal hemoperfusion. Hemodialysis should be considered as an alternative when charcoal hemoperfusion is not feasible and multiple-dose oral charcoal is ineffective because of intractable emesis. Serum theophylline concentrations may rebound 5-10 mcg/mL after discontinuation of charcoal hemoperfusion or hemodialysis due to redistribution of theophylline from the tissue compartment. Peritoneal dialysis is ineffective for theophylline removal; exchange transfusions in neonates have been minimally effective.

Contraindications

Capsule; Solution, ElixirSubstance-powder; Sustained-release tabletsCapsule, Extended Release

Teosona Elixir is contraindicated in patients with a history of hypersensitivity to theophylline or other components in the product.

Teosona in 5% Dextrose Injections USP are contraindicated in patients with a history of hypersensitivity to Teosona or other components in the product.

Solutions containing dextrose may be contraindicated in patients with known allergy to corn or corn products.

Teosona (theophylline anhydrous capsule) ® is contraindicated in patients with a history of hypersensitivity to theophylline or other components in the product.

Undesirable effects

Capsule; Solution, ElixirSubstance-powder; Sustained-release tabletsCapsule, Extended Release

Adverse reactions associated with theophylline are generally mild when peak serum theophylline concentrations are < 20 mcg/mL and mainly consist of transient caffeine-like adverse effects such as nausea, vomiting, headache, and insomnia. When peak serum theophylline concentrations exceed 20 mcg/mL, however, theophylline produces a wide range of adverse reactions including persistent vomiting, cardiac arrhythmias, and intractable seizures which can be lethal (see OVERDOSAGE). The transient caffeine-like adverse reactions occur in about 50% of patients when theophylline therapy is initiated at doses higher than recommended initial doses (e.g., > 300 mg/day in adults and > 12 mg/kg/day in children beyond > 1 year of age). During the initiation of theophylline therapy, caffeine-like adverse effects may transiently alter patient behavior, especially in school age children, but this response rarely persists.

Initiation of theophylline therapy at a low dose with subsequent slow titration to a predetermined agerelated maximum dose will significantly reduce the frequency of these transient adverse effects (see In a small percentage of patients ( < 3% of children and < 10% of adults) the caffeine-like adverse effects persist during maintenance therapy, even at peak serum theophylline concentrations within the therapeutic range (i.e., 10-20 mcg/mL). Dosage reduction may alleviate the caffeine-like adverse effects in these patients, however, persistent adverse effects should result in a reevaluation of the need for continued theophylline therapy and the potential therapeutic benefit of alternative treatment.

Other adverse reactions that have been reported at serum theophylline concentrations < 20 mcg/mL include diarrhea, irritability, restlessness, fine skeletal muscle tremors, and transient diuresis. In patients with hypoxia secondary to COPD, multifocal atrial tachycardia and flutter have been reported at serum theophylline concentrations ≥ 15 mcg/mL. There have been a few isolated reports of seizures at serum theophylline concentrations < 20 mcg/mL in patients with an underlying neurological disease or in elderly patients. The occurrence of seizures in elderly patients with serum theophylline concentrations < 20 mcg/mL may be secondary to decreased protein binding resulting in a larger proportion of the total serum theophylline concentration in the pharmacologically active unbound form. The clinical characteristics of the seizures reported in patients with serum theophylline concentrations < 20 mcg/mL have generally been milder than seizures associated with excessive serum theophylline concentrations resulting from an overdose (i.e., they have generally been transient, often stopped without anticonvulsant therapy, and did not result in neurological residua).

Table IV: Manifestations of theophylline toxicity.*

Sign/Symptom Percentage of patients reported with sign or symptom
Acute Overdose
(Large Single Inges tion)		 Chronic Overdos age
(Multiple Exces sive Doses )
Study 1
(n=157)		 Study 2
(n=14)		 Study 1
(n=92)		 Study 2
(n=102)
Asymptomatic NR** 0 NR** 6
Gastrointestinal
  Vomiting 73 93 30 61
  Abdominal Pain NR** 21 NR** 12
  Diarrhea NR** 0 NR** 14
  Hematemesis NR** 0 NR** 2
Metabolic/Other
  Hypokalemia 85 79 44 43
  Hyperglycemia 98 NR** 18 NR**
  Acid/base disturbance 34 21 9 5
  Rhabdomyolysis NR** 7 NR** 0
Cardiovascular
  Sinus tachycardia 100 86 100 62
  Other supraventricular tachycardias 2 21 12 14
  Ventricular premature beats 3 21 10 19
  Atrial fibrillation or flutter 1 NR** 12 NR**
  Multifocal atrial tachycardia 0 NR** 2 NR**
  Ventricular arrhythmias with hemodynamic instability 7 14 40 0
  Hypotension/shock NR** 21 NR** 8
Neurologic
  Nervousness NR** 64 NR** 21
  Tremors 38 29 16 14
  Disorientation NR** 7 NR** 11
  Seizures 5 14 14 5
  Death 3 21 10 4
*These data are derived from two studies in patients with serum theophylline concentrations > 30 mcg/mL. In the first study (Study #1 - Shanon, Ann Intern Med 1993;119:1161-67), data were prospectively collected from 249 consecutive cases of theophylline toxicity referred to a regional poison center for consultation. In the second study (Study #2 - Sessler, Am J Med 1990;88:567-76), data were retrospectively collected from 116 cases with serum theophylline concentrations > 30 three emergency departments. Differences in the incidence of manifestations of theophylline toxicity between the two studies may reflect sample selection as a result of study design (e.g., in Study #1, 48% of the patients had acute intoxications versus only 10% in Study #2) and different methods of reporting results.
**NR = Not reported in a comparable manner.

Adverse reactions associated with Teosona are generally mild when serum Teosona concentrations are < 20 mcg/mL and mainly consist of transient caffeine-like adverse effects such as nausea, vomiting, headache, and insomnia. When serum Teosona concentrations exceed 20 mcg/mL, however, Teosona produces a wide range of adverse reactions including persistent vomiting, cardiac arrhythmias, and intractable seizures which can be lethal (see OVERDOSAGE).

Other adverse reactions that have been reported at serum Teosona concentrations < 20 mcg/mL include diarrhea, irritability, restlessness, fine skeletal muscle tremors, and transient diuresis. In patients with hypoxia secondary to COPD, multifocal atrial tachycardia and flutter have been reported at serum Teosona concentrations ¡Ý15 mcg/mL. There have been a few isolated reports of seizures at serum Teosona concentrations < 20 mcg/mL in patients with an underlying neurological disease or in elderly patients. The occurrence of seizures in elderly patients with serum Teosona concentrations < 20 mcg/mL may be secondary to decreased protein binding resulting in a larger proportion of the total serum Teosona concentration in the pharmacologically active unbound form. The clinical characteristics of the seizures reported in patients with serum Teosona concentrations < 20 mcg/mL have generally been milder than seizures associated with excessive serum Teosona concentrations resulting from an overdose (i.e., they have generally been transient, often stopped without anticonvulsant therapy, and did not result in neurological residua). Hypercalcemia has been reported in a patient with hyperthyroid disease at therapeutic Teosona concentrations (see OVERDOSAGE).

Table IV. Manifestations of Teosona toxicity.*

Sign/Symptom Percentage of patients reported with sign or symptom
Acute Overdose
(Large Single Ingestion)		 Chronic Overdosage
(Multiple Excessive Doses)
Study 1
(n=157)		 Study 2
(n=14)		 Study 1
(n=92)		 Study 2
(n=102)
Asymptomatic NR** 0 NR** 6
Gastrointestinal
  Vomiting 73 93 30 61
  Abdominal Pain NR** 21 NR** 12
  Diarrhea NR** 0 NR** 14
  Hematemesis NR** 0 NR** 2
Metabolic/Other
  Hypokalemia 85 79 44 43
  Hyperglycemia 98 NR** 18 NR**
  Acid/base disturbance 34 21 9 5
  Rhabdomyolysis NR** 7 NR** 0
Cardiovascular
  Sinus tachycardia 100 86 100 62
  Other supraventricular tachycardias 2 21 12 14
  Ventricular premature beats 3 21 10 19
  Atrial fibrillation or flutter 1 NR** 12 NR**
  Multifocal atrial tachycardia 0 NR** 2 NR**
  Ventricular arrhythmias with hemodynamic instability   7 14 40 0
  Hypotension/shock NR** 21 NR** 8
Neurologic
  Nervousness NR** 64 NR** 21
  Tremors 38 29 16 14
  Disorientation NR** 7 NR** 11
  Seizures 5 14 14 5
  Death 3 21 10 4
* These data are derived from two studies in patients with serum Teosona concentrations > 30 mcg/mL. In the first study (Study #1 - Shanon, Ann lntern Med 1993;119:1161-67), data were prospectively collected from 249 consecutive cases of Teosona toxicity referred to a regional poison center for consultation. In the second study (Study #2 - Sessler, Am J Med 1990;88:567-76), data were retrospectively collected from 116 cases with serum Teosona concentrations > 30 mcg/mL among 6000 blood samples obtained for measurement of serum Teosona concentrations in three emergency departments. Differences in the incidence of manifestations of Teosona toxicity between the two studies may reflect sample selection as a result of study design (e.g., in Study #1, 48% of the patients had acute intoxications versus only 10% in Study #2) and different methods of reporting results.
** NR = Not reported in a comparable manner.

Reactions which may occur because of the solution or the technique of administration include febrile response, infection at the site of injection, venous thrombosis or phlebitis extending from the site of injection, extravasation and hypervolemia.

Adverse reactions associated with theophylline are generally mild when peak serum theophylline concentrations are < 20 mcg/ mL and mainly consist of transient caffeine-like adverse effects such as nausea, vomiting, headache, and insomnia. When peak serum theophylline concentrations exceed 20 mcg/mL, however, theophylline produces a wide range of adverse reactions including persistent vomiting, cardiac arrhythmias, and intractable seizures which can be lethal (see OVERDOSAGE). The transient caffeine-like adverse reactions occur in about 50% of patients when theophylline therapy is initiated at doses higher than recommended initial doses (e.g., > 300 mg/day in adults and > 12 mg/kg/day in children beyond 1 year of age). During the initiation of theophylline therapy, caffeine-like adverse effects may transiently alter patient behavior, especially in school age children, but this response rarely persists. Initiation of theophylline therapy at a low dose with subsequent slow titration to a predetermined age-related maximum dose will significantly reduce the frequency of these transient adverse effects (see DOSAGE AND ADMINISTRATION, Table V). In a small percentage of patients ( < 3% of children and < 10% of adults) the caffeine-like adverse effects persist during maintenance therapy, even at peak serum theophylline concentrations within the therapeutic range (i.e., 10-20 mcg/mL). Dosage reduction may alleviate the caffeine-like adverse effects in these patients, however, persistent adverse effects should result in a reevaluation of the need for continued theophylline therapy and the potential therapeutic benefit of alternative treatment.

Other adverse reactions that have been reported at serum theophylline concentrations < 20 mcg/mL include diarrhea, irritability, restlessness, fine skeletal muscle tremors, and transient diuresis. In patients with hypoxia secondary to COPD, multifocal atrial tachycardia and flutter have been reported at serum theophylline concentrations ≥ 15 mcg/mL. There have been a few isolated reports of seizures at serum theophylline concentrations < 20 mcg/mL in patients with an underlying neurological disease or in elderly patients. The occurrence of seizures in elderly patients with serum theophylline concentrations < 20 mcg/mL may be secondary to decreased protein binding resulting in a larger proportion of the total serum theophylline concentration in the pharmacologically active unbound form. The clinical characteristics of the seizures reported in patients with serum theophylline concentrations < 20 mcg/mL have generally been milder than seizures associated with excessive serum theophylline concentrations resulting from an overdose (i.e., they have generally been transient, often stopped without anticonvulsant therapy, and did not result in neurological residua).

Table IV. Manifestations of theophylline toxicity.*

  Percentage of patients reported with sign or symptom
Acute Overdose
(Large Single Ingestion)		 Chronic Overdosage
(Multiple Excessive Doses)
Sign/Symptom Study 1
(n=157)		 Study 2
(n=14)		 Study 1
(n=92)		 Study 2
(n=102)
Asymptomatic NR** 0 NR** 6
Gastrointestinal
  Vomiting 73 93 30 61
  Abdominal pain NR** 21 NR** 12
  Diarrhea NR** 0 NR** 14
  Hematemesis NR** 0 NR** 2
Metabolic/Other
  Hypokalemia 85 79 44 43
  Hyperglycemia 98 NR** 18 NR**
  Acid/base disturbance 34 21 9 5
  Rhabdomyolysis NR** 7 NR** 0
Cardiovascular
  Sinus tachycardia 100 86 100 62
  Other supraventricular tachycardias 2 21 12 14
  Ventricular premature beats 3 21 10 19
  Atrial fibrillation or flutter 1 NR** 12 NR**
  Multifocal atrial tachycardia 0 NR** 2 NR**
Ventricular arrhythmias with
  hemodynamic instability 7 14 40 0
  Hypotension/shock NR** 21 NR** 8
Neurologic
  Nervousness NR** 64 NR** 21
  Tremors 38 29 16 14
  Disorientation NR** 7 NR** 11
  Seizures 5 14 14 5
  Death 3 21 10 4
* These data are derived from two studies in patients with serum theophylline concentrations > 30 mcg/mL. In the first study (Study #1—Shanon, Ann Intern Med 1993;119:1161-67), data were prospectively collected from 249 consecutive cases of theophylline toxicity referred to a regional poison center for consultation. In the second study (Study #2—Sessler, Am J Med 1990;88:567-76), data were retrospectively collected from 116 cases with serum theophylline concentrations > 30 mcg/mL among 6000 blood samples obtained for measurement of serum theophylline concentrations in three emergency departments. Differences in the incidence of manifestations of theophylline toxicity between the two studies may reflect sample selection as a result of study design (e.g., in Study #1, 48% of the patients had acute intoxications versus only 10% in Study #2) and different methods of reporting results.
** NR =Not reported in a comparable manner.

Therapeutic indications

Teosona in 5% Dextrose Injections USP are indicated as an adjunct to inhaled beta-2 selective agonists and systemically administered corticosteroids for the treatment of acute exacerbations of the symptoms and reversible airflow obstruction associated with asthma and other chronic lung diseases, e.g., emphysema and chronic bronchitis.

Pharmacokinetic properties

Capsule; Solution, ElixirSubstance-powder; Sustained-release tabletsCapsule, Extended ReleaseOverview

Theophylline is rapidly and completely absorbed after oral administration in solution or immediaterelease solid oral dosage form. Theophylline does not undergo any appreciable pre-systemic elimination, distributes freely into fat-free tissues and is extensively metabolized in the liver.

The pharmacokinetics of theophylline vary widely among similar patients and cannot be predicted by age, sex, body weight or other demographic characteristics. In addition, certain concurrent illnesses and alterations in normal physiology (see Table I) and co-administration of other drugs (see Table II) can significantly alter the pharmacokinetic characteristics of theophylline. Within-subject variability in metabolism has also been reported in some studies, especially in acutely ill patients. It is, therefore, recommended that serum theophylline concentrations be measured frequently in acutely ill patients (e.g., at 24-hour intervals) and periodically in patients receiving long-term therapy, e.g., at 6-12 month intervals. More frequent measurements should be made in the presence of any condition that may significantly alter theophylline clearance (see PRECAUTIONS, Laboratory tests).

Table I: Mean and range of total body clearance and half-life of theophylline related to age and altered physiological states¶

Population characteristics Total body clearance* mean (range)†† (mL/kg/min) Half-life mean (range)†† (hr)
Age
Premature neonates postnatal age 3-15 days 0.29 (0.09-0.49) 30 (17-43)
postnatal age 25-57 days 0.64 (0.04-1.2) 20 (9.4-30.6)
T erm infants
postnatal age 1-2 days NR† 25.7 (25-26.5)
postnatal age 3-30 weeks NR† 11 (6-29)
Children
1-4 years 1.7 (0.5-2.9) 3.4 (1.2-5.6)
4-12 years 1.6 (0.8-2.4) NR†
13-15 years 0.9 (0.48-1.3) NR†
16-17 years 1.4 (0.2-2.6) 3.7 (1.5-5.9)
Adults (16-60 years)otherwise healthy
non-smoking asthmatics 0.65 (0.27-1.03) 8.7 (6.1-12.8)
Elderly ( > 60 years)
non-smokers with normal cardiac, liver, and renal function 0.41 (0.21-0.61) 9.8 (1.6-18)
Concurrent illness or altered physiological state
Acute pulmonary edema 0.33** (0.07-2.45) 19** (3.1-82)
C0PD- > 60 years, stable 0.54 (0.44-0.64) 11 (9.4-12.6)
non-smoker > 1 year
COPD with cor pulmonale 0.48 (0.08-0.88) NR†
Cystic fibrosis (14-28 years) 1.25 (0.31-2.2) 6.0 (1.8-10.2)
Fever associated with acute viral respiratory illness (children 9-15 years) NR† 7.0 (1.0-13)
Liver disease - cirrhosis 0.31** (0.1-0.7) 32** (10-56)
acute hepatitis 0.35 (0.25-0.45) 19.2 (16.6-21.8)
cholestasis 0.65 (0.25-1.45) 14.4 (5.7-31.8)
Pregnancy - 1st trimester NR† 8.5 (3.1-13.9)
2nd trimester NR† 8.8 (3.8-13.8)
3rd trimester NR† 13.0 (8.4-17.6)
Sepsis with multi-organ failure 0.47 (0.19-1.9) 18.8 (6.3-24.1)
Thyroid disease - hypothyroid 0.38 (0.13-0.57) 11.6 (8.2-25)
hyperthyroid 0.8 (0.68-0.97) 4.5 (3.7-5.6)
¶For various North American patient populations from literature reports. Different rates of elimination and consequent dosage requirements have been observed among other peoples.
*Clearance represents the volume of blood completely cleared of theophylline by the liver in one minute. Values listed were generally determined at serum theophylline concentrations < 20 mcg/mL; clearance may decrease and half-life may increase at higher serum concentrations due to non-linear pharmacokinetics.
††Reported range or estimated range (mean ± 2 SD) where actual range not reported.
†NR = not reported or not reported in a comparable format.
**Median

Note: In addition to the factors listed above, theophylline clearance is increased and half-life decreased by low carbohydrate/high protein diets, parenteral nutrition, and daily consumption of charcoal-broiled beef. A high carbohydrate/low protein diet can decrease the clearance and prolong the half-life of theophylline.

Absorption

Theophylline is rapidly and completely absorbed after oral administration in solution or immediaterelease solid oral dosage form. After a single dose of 5 mg/kg in adults, a mean peak serum concentration of about 10 mcg/mL (range 5-15 mcg/mL) can be expected 1-2 hr after the dose. Coadministration of theophylline with food or antacids does not cause clinically significant changes in the absorption of theophylline from immediate-release dosage forms.

Distribution

Once theophylline enters the systemic circulation, about 40% is bound to plasma protein, primarily albumin. Unbound theophylline distributes throughout body water, but distributes poorly into body fat. The apparent volume of distribution of theophylline is approximately 0.45 L/kg (range 0.3-0.7 L/kg) based on ideal body weight. Theophylline passes freely across the placenta, into breast milk and into the cerebrospinal fluid (CSF). Saliva theophylline concentrations approximate unbound serum concentrations, but are not reliable for routine or therapeutic monitoring unless special techniques are used. An increase in the volume of distribution of theophylline, primarily due to reduction in plasma protein binding, occurs in premature neonates, patients with hepatic cirrhosis, uncorrected acidemia, the elderly and in women during the third trimester of pregnancy. In such cases, the patient may show signs of toxicity at total (bound +unbound) serum concentrations of theophylline in the therapeutic range (10- 20 mcg/mL) due to elevated concentrations of the pharmacologically active unbound drug. Similarly, a patient with decreased theophylline binding may have a subtherapeutic total drug concentration while the pharmacologically active unbound concentration is in the therapeutic range. If only total serum theophylline concentration is measured, this may lead to an unnecessary and potentially dangerous dose increase. In patients with reduced protein binding, measurement of unbound serum theophylline concentration provides a more reliable means of dosage adjustment than measurement of total serum theophylline concentration. Generally, concentrations of unbound theophylline should be maintained in the range of 6-12 mcg/mL.

Metabolism

Following oral dosing, theophylline does not undergo any measurable first-pass elimination. In adults and children beyond one year of age, approximately 90% of the dose is metabolized in the liver. Biotransformation takes place through demethylation to 1-methylxanthine and 3-methylxanthine and hydroxylation to 1,3-dimethyluric acid. 1-methylxanthine is further hydroxylated, by xanthine oxidase, to 1-methyluric acid. About 6% of a theophylline dose is N-methylated to caffeine. Theophylline demethylation to 3-methylxanthine is catalyzed by cytochrome P-450 1A2, while cytochromes P-450 2E1 and P-450 3A3 catalyze the hydroxylation to 1,3-dimethyluric acid. Demethylation to 1- methylxanthine appears to be catalyzed either by cytochrome P-450 1A2 or a closely related cytochrome. In neonates, the N-demethylation pathway is absent while the function of the hydroxylation pathway is markedly deficient. The activity of these pathways slowly increases to maximal levels by one year of age.

Caffeine and 3-methylxanthine are the only theophylline metabolites with pharmacologic activity. 3- methylxanthine has approximately one tenth the pharmacologic activity of theophylline and serum concentrations in adults with normal renal function are < 1 mcg/mL. In patients with end-stage renal disease, 3-methylxanthine may accumulate to concentrations that approximate the unmetabolized theophylline concentration. Caffeine concentrations are usually undetectable in adults regardless of renal function. In neonates, caffeine may accumulate to concentrations that approximate the unmetabolized theophylline concentration and thus, exert a pharmacologic effect.

Both the N-demethylation and hydroxylation pathways of theophylline biotransformation are capacitylimited. Due to the wide intersubject variability of the rate of theophylline metabolism, non-linearity of elimination may begin in some patients at serum theophylline concentrations < 10 mcg/mL. Since this non-linearity results in more than proportional changes in serum theophylline concentrations with changes in dose, it is advisable to make increases or decreases in dose in small increments in order to achieve desired changes in serum theophylline concentrations (see DOSAGE AND ADMINISTRATION, Table VI). Accurate prediction of dose-dependency of theophylline metabolism in patients a priori is not possible, but patients with very high initial clearance rates (i.e., low steady state serum theophylline concentrations at above average doses) have the greatest likelihood of experiencing large changes in serum theophylline concentration in response to dosage changes.

Excretion

In neonates, approximately 50% of the theophylline dose is excreted unchanged in the urine. Beyond the first three months of life, approximately 10% of the theophylline dose is excreted unchanged in the urine. The remainder is excreted in the urine mainly as 1,3-dimethyluric acid (35-40%), 1-methyluric acid (20-25%) and 3-methylxanthine (15-20%). Since little theophylline is excreted unchanged in the urine and since active metabolites of theophylline (i.e., caffeine, 3-methylxanthine) do not accumulate to clinically significant levels even in the face of end-stage renal disease, no dosage adjustment for renal insufficiency is necessary in adults and children > 3 months of age. In contrast, the large fraction of the theophylline dose excreted in the urine as unchanged theophylline and caffeine in neonates requires careful attention to dose reduction and frequent monitoring of serum theophylline concentrations in neonates with reduced renal function (See WARNINGS).

Serum Concentrations At Steady State

After multiple doses of theophylline, steady state is reached in 30-65 hours (average 40 hours) in adults. At steady state, on a dosage regimen with 6-hour intervals, the expected mean trough concentration is approximately 60% of the mean peak concentration, assuming a mean theophylline halflife of 8 hours. The difference between peak and trough concentrations is larger in patients with more rapid theophylline clearance. In patients with high theophylline clearance and half-lives of about 4-5 hours, such as children age 1 to 9 years, the trough serum theophylline concentration may be only 30% of peak with a 6-hour dosing interval. In these patients a slow release formulation would allow a longer dosing interval (8-12 hours) with a smaller peak/trough difference.

Overview

The pharmacokinetics of Teosona vary widely among similar patients and cannot be predicted by age, sex, body weight or other demographic characteristics. In addition, certain concurrent illnesses and alterations in normal physiology (see Table I) and co-administration of other drugs (see Table II) can significantly alter the pharmacokinetic characteristics of Teosona. Within-subject variability in metabolism has also been reported in some studies, especially in acutely ill patients. It is, therefore, recommended that serum Teosona concentrations be measured frequently in acutely ill patients receiving intravenous Teosona (e.g., at 24-hr intervals). More frequent measurements should be made during the initiation of therapy and in the presence of any condition that may significantly alter Teosona clearance (see PRECAUTIONS, Laboratory tests).

Table l. Mean and range of total body clearance and half-life of Teosona related to age and altered physiological states.¶

Population characteristics Total body clearance* mean (range)†† (mL/kg/min) Half-life mean (range)†† (hr)
Age
Premature neonates 0.29 (0.09-0.49) 30 (17-43)
postnatal age 3-15 days 0.64 (0.04-1.2) 20 (9.4-30.6)
postnatal age 25-57 days NR† 25.7 (25-26.5)
Term infants  
postnatal age 1-2 days NR† 11 (6-29)
postnatal age 3-30 weeks 1.7 (0.5-2.9) 3.4 (1.2-5.6)
Children  
1-4 years 1.6 (0.8-2.4) NR†
4-12 years 0.9 (0.48-1.3) NR†
13-15 years 1.4 (0.2-2.6) 3.7 (1.5-5.9)
6-17 years 0.65 (0.27-1.03) 8.7 (6.1-12.8)
Adults (16-60 years) otherwise healthy non-smoking asthmatics 0.41 (0.21-0.61) 9.8 (1.6-18)
Elderly ( > 60 years) non-smokers with normal cardiac, liver, and renal function 0.33** (0.07-2.45) 19** (3.1-82)
Concurrent illness or altered physiological state
Acute pulmonary edema 0.54 (0.44-0.64) 11 (9.4-12.6)
COPD- > 60 years, stable non-smoker > 1 year 0.48 (0.08-0.88) NR†
COPD with cor pulmonale Cystic fibrosis (14-28 years) 1.25 (0.31-2.2) 6.0 (1.8-10.2)
Fever associated with-acute viral respiratory illness (children 9-15 years) NR† 7.0 (1.0-13)
Liver disease - cirrhosis 0.31** (0.1-0.7) 32** (10-56)
  acute hepatitis 0.35 (0.25-0.45) 19.2 (16.6-21.8)
  cholestasis 0.65 (0.25-1.45) 14.4 (5.7-31.8)
Pregnancy - 1st trimester NR† 8.5 (3.1-13.9)
   2nd trimester NR† 8.8 (3.8-13.8)
  3rd trimester NR† 13.0 (8.4-17.6)
Sepsis with multi-organ failure 0.47 (0.19-1.9) 18.8 (6.3-24.1)
Thyroid disease - hypothyroid 0.38 (0.13-0.57) 11.6 (8.2-25)
hyperthyroid 0.8 (0.68-0.97) 4.5 (3.7-5.6)
¶ For various North American patient populations from literature reports. Different rates of elimination and consequent dosage requirements have been observed among other peoples.
* Clearance represents the volume of blood completely cleared of Teosona by the liver in one minute. Values listed were generally determined at serum Teosona concentrations < 20 mcg/mL; clearance may decrease and half-life may increase at higher serum concentrations due to non-linear pharmacokinetics.
† † Reported range or estimated range (mean ± 2 SD) where actual range not reported.
† NR = not reported or not reported in a comparable format.
** Median

Note: In addition to the factors listed above, Teosona clearance is increased and half-life decreased by low carbohydrate/high protein diets, parenteral nutrition, and daily consumption of charcoal-broiled beef. A high carbohydrate/low protein diet can decrease the clearance and prolong the half-life of Teosona.

Distribution

Once Teosona enters the systemic circulation, about 40% is bound to plasma protein, primarily albumin. Unbound Teosona distributes throughout body water, but distributes poorly into body fat. The apparent volume of distribution of Teosona is approximately 0.45 L/kg (range 0.3-0.7 L/kg) based on ideal body weight. Teosona passes freely across the placenta, into breast milk and into the cerebrospinal fluid (CSF). Saliva Teosona concentrations approximate unbound serum concentrations, but are not reliable for routine or therapeutic monitoring unless special techniques are used. An increase in the volume of distribution of Teosona, primarily due to reduction in plasma protein binding, occurs in premature neonates, patients with hepatic cirrhosis, uncorrected acidemia, the elderly and in women during the third trimester of pregnancy. In such cases, the patient may show signs of toxicity at total (bound + unbound) serum concentrations of Teosona in the therapeutic range (10-20 mcg/mL) due to elevated concentrations of the pharmacologically active unbound drug. Similarly, a patient with decreased Teosona binding may have a sub-therapeutic total drug concentration while the pharmacologically active unbound concentration is in the therapeutic range. If only total serum Teosona concentration is measured, this may lead to an unnecessary and potentially dangerous dose increase. In patients with reduced protein binding, measurement of unbound serum Teosona concentration provides a more reliable means of dosage adjustment than measurement of total serum Teosona concentration. Generally, concentrations of unbound Teosona should be maintained in the range of 6-12 mcg/mL.

Metabolism

In adults and children beyond one year of age, approximately 90% of the dose is metabolized in the liver. Biotransformation takes place through demethylation to 1-methylxanthine and 3-methylxanthine and hydroxylation to 1,3-dimethyluric acid. 1-methylxanthine is further hydroxylated, by xanthine oxidase, to 1-methyluric acid. About 6% of a Teosona dose is N-methylated to caffeine. Teosona demethylation to 3-methylxanthine is catalyzed by cytochrome P-450 1A2, while cytochromes P-450 2E1 and P-450 3A3 catalyze the hydroxylation to 1,3-dimethyluric acid. Demethylation to 1-methylxanthine appears to be catalyzed either by cytochrome P-450 1A2 or a closely related cytochrome. In neonates, the N-demethylation pathway is absent while the function of the hydroxylation pathway is markedly deficient. The activity of these pathways slowly increases to maximal levels by one year of age.

Caffeine and 3-methylxanthine are the only Teosona metabolites with pharmacologic activity. 3-methylxanthine has approximately one tenth the pharmacologic activity of Teosona and serum concentrations in adults with normal renal function are < 1 mcg/mL. In patients with endstage renal disease, 3-methylxanthine may accumulate to concentrations that approximate the unmetabolized Teosona concentration. Caffeine concentrations are usually undetectable in adults regardless of renal function. In neonates, caffeine may accumulate to concentrations that approximate the unmetabolized Teosona concentration and thus, exert a pharmacologic effect.

Both the N-demethylation and hydroxylation pathways of Teosona biotransformation are capacity-limited. Due to the wide intersubject variability of the rate of Teosona metabolism, non-linearity of elimination may begin in some patients at serum Teosona concentrations < 10 mcg/mL. Since this non-linearity results in more than proportional changes in serum Teosona concentrations with changes in dose, it is advisable to make increases or decreases in dose in small increments in order to achieve desired changes in serum Teosona concentrations (see DOSAGE AND ADMINISTRATION, Table VI). Accurate prediction of dosedependency of Teosona metabolism in patients a priori is not possible, but patients with very high initial clearance rates (i.e., low steady state serum Teosona concentrations at above average doses) have the greatest likelihood of experiencing large changes in serum Teosona concentration in response to dosage changes.

Excretion

In neonates, approximately 50% of the Teosona dose is excreted unchanged in the urine. Beyond the first three months of life, approximately 10% of the Teosona dose is excreted unchanged in the urine. The remainder is excreted in the urine mainly as 1,3-dimethyluric acid (35-40%), 1-methyluric acid (20-25%) and 3-methylxanthine (15-20%). Since little Teosona is excreted unchanged in the urine and since active metabolites of Teosona (i.e., caffeine, 3-methylxanthine) do not accumulate to clinically significant levels even in the face of end-stage renal disease, no dosage adjustment for renal insufficiency is necessary in adults and children > 3 months of age. In contrast, the large fraction of the Teosona dose excreted in the urine as unchanged Teosona and caffeine in neonates requires careful attention to dose reduction and frequent monitoring of serum Teosona concentrations in neonates with reduced renal function (see WARNINGS).

Serum Concentrations at Steady State

In a patient who has received no Teosona in the previous 24 hours, a loading dose of intravenous Teosona of 4.6 mg/kg, calculated on the basis of ideal body weight and administered over 30 minutes, on average, will produce a maximum postdistribution serum concentration of 10 mcg/mL with a range of 6-16 mcg/mL. In non-smoking adults, initiation of a constant intravenous Teosona infusion of 0.4 mg/kg/hr at the completion of the loading dose, on average, will result in a steady-state concentration of 10 mcg/mL with a range of 7-26 mcg/mL. The mean and range of steady-state serum concentrations are similar when the average child (age 1 to 9 years) is given a loading dose of 4.6 mg/kg Teosona followed by a constant intravenous infusion of 0.8 mg/kg/hr. (See DOSAGE AND ADMINISTRATION.)

Overview

Theophylline is rapidly and completely absorbed after oral administration in solution or immediate-release solid oral dosage form. Theophylline does not undergo any appreciable pre-systemic elimination, distributes freely into fat-free tissues and is extensively metabolized in the liver.

The pharmacokinetics of theophylline vary widely among similar patients and cannot be predicted by age, sex, body weight or other demographic characteristics. In addition, certain concurrent illnesses and alterations in normal physiology (see Table I) and co-administration of other drugs (see Table II) can significantly alter the pharmacokinetic characteristics of theophylline. Within-subject variability in metabolism has also been reported in some studies, especially in acutely ill patients. It is, therefore, recommended that serum theophylline concentrations be measured frequently in acutely ill patients (e.g., at 24-hr intervals) and periodically in patients receiving long-term therapy, e.g., at 6-12 month intervals. More frequent measurements should be made in the presence of any condition that may significantly alter theophylline clearance (see PRECAUTIONS, Laboratory Tests).

Table I. Mean and range of total body clearance and half-life of theophylline related to age and altered physiological states.¶

Population Characteristics Total body clearance*
mean (range)††
(mL/kg/min)		 Half-life
Mean (range)††
(hr)
Age
Premature neonates
  postnatal age 3-15 days 0.29 (0.09-0.49) 30 (17-43)
  postnatal age 25-57 days 0.64 (0.04-1.2) 20 (9.4-30.6)
Term infants
  postnatal age 1-2 days NR† 25.7 (25-26.5)
  postnatal age 3-30 weeks NR† 11 (6-29)
Children
  1-4 years 1.7 (0.5-2.9) 3.4 (1.2-5.6)
  4-12 years 1.6 (0.8-2.4) NR†
  13-15 years 0.9 (0.48-1.3) NR†
  6-17 years 1.4 (0.2-2.6) 3.7 (1.5-5.9)
Adults (16-60 years)
  otherwise healthy non-smoking asthmatics 0.65 (0.27-1.03) 8.7 (6.1-12.8)
Elderly ( > 60 years)
  non-smokers with normal cardiac, liver, and renal function 0.41 (0.21-0.61) 9.8 (1.6-18)
Concurrent illness or altered physiological state
  Acute pulmonary edema 0.33**(0.07-2.45) 19**(3.1-82)
  COPD > 60 years, stable non-smoker > 1 year 0.54 (0.44-0.64) 11 (9.4-12.6)
  COPD with cor-pulmonale 0.48 (0.08-0.88) NR†
  Cystic fibrosis (14-28 years) 1.25 (0.31-2.2) 6.0 (1.8-10.2)
  Fever associated with acute viral respiratory illness (children 9-15 years) NR† 7.0 (1.0-13)
Liver disease – cirrhosis 0.31**(0.1-0.7) 32**(10-56)
  acute hepatitis 0.35 (0.25-0.45) 19.2 (16.6-21.8)
  cholestasis 0.65 (0.25-1.45) 14.4 (5.7-31.8)
Pregnancy – 1st trimester NR† 8.5 (3.1-13.9)
  2nd trimester NR† 8.8 (3.8-13.8)
  3rd trimester NR† 13.0 (8.4-17.6)
Sepsis with multi-organ failure 0.47 (0.19-1.9) 18.8 (6.3-24.1)
Thyroid disease – hypothyroid 0.38 (0.13-0.57) 11.6 (8.2-25)
  hyperthyroid 0.8 (0.68-0.97) 4.5 (3.7-5.6)
¶ For various North American patient populations from literature reports. Different rates of elimination and consequent dosage requirements have been observed among other peoples.
* Clearance represents the volume of blood completely cleared of theophylline by the liver in one minute. Values listed were generally determined at serum theophylline concentrations < 20 mcg/mL; clearance may decrease and half-life may increase at higher serum concentrations due to non-linear pharmacokinetics.
†† Reported range or estimated range (mean ± 2 SD) where actual range not reported.
† NR =not reported or not reported in a comparable format.
** Median
Note: In addition to the factors listed above, theophylline clearance is increased and half-life decreased by low carbohydrate/high protein diets, parenteral nutrition, and daily consumption of charcoal-broiled beef. A high carbohydrate/low protein diet can decrease the clearance and prolong the half-life of theophylline.
Absorption

Theophylline is rapidly and completely absorbed after oral administration in solution or immediate-release solid oral dosage form. After a single immediate-release dose of 5 mg/kg in adults, a mean peak serum concentration of about 10 mcg/mL (range 5-15 mcg/ mL) can be expected 1-2 hr after dose. Co-administration of theophylline with food or antacids does not cause clinically significant changes in the absorption of theophylline from immediate-release dosage forms.

Teosona (theophylline anhydrous capsule) ® capsules contain hundreds of coated beads of theophylline. Each bead is an individual extended-release delivery system. After dissolution of the capsules these beads are released and distributed in the gastrointestinal tract, thus minimizing the probability of high local concentrations of theophylline at any particular site.

In a 6-day multiple-dose study involving 18 subjects (with theophylline clearance rates between 0.57 and 1.02 mL/kg/min) who had fasted overnight and 2 hours after morning dosing, Teosona (theophylline anhydrous capsule) ® given once daily in a dose of 1500 mg produced serum theophylline levels that ranged between 5.7 mcg/mL and 22 mcg/mL. The mean minimum and maximum values were 11.6 mcg/mL and 18.1 mcg/mL, respectively, with an average peak-trough difference of 6.5 mcg/mL. The mean percent fluctuation [(Cmax–Cmin /Cmin) x 100] equals 80%. A 24-hour single-dose study demonstrated an approximately proportional increase in serum levels as the dose was increased from 600 to 1500 mg.

Taking Teosona (theophylline anhydrous capsule) ® with a high-fat-content meal may result in a significant increase in the peak serum level and in the extent of absorption of theophylline as compared to administration in the fasted state (see PRECAUTIONS, Drug/Food Interactions).

Following the single-dose administration (8 mg/kg) of Teosona (theophylline anhydrous capsule) ® to 20 normal subjects who had fasted overnight and 2 hours after morning dosing, peak serum theophylline concentrations of 4.8 ± 1.5 (SD) mcg/mL were obtained at 13.3 ± 4.7 (SD) hours. The amount of the dose absorbed was approximately 13% at 3 hours, 31% at 6 hours, 55% at 12 hours, 70% at 16 hours, and 88% at 24 hours. The extent of theophylline bioavailability from Teosona (theophylline anhydrous capsule) ® was comparable to the most widely used 12-hour extended-release product when both products were administered every 12 hours.

Distribution

Once theophylline enters the systemic circulation, about 40% is bound to plasma protein, primarily albumin. Unbound theophylline distributes throughout body water, but distributes poorly into body fat. The apparent volume of distribution of theophylline is approximately 0.45 L/kg (range 0.3-0.7 L/kg) based on ideal body weight. Theophylline passes freely across the placenta, into breast milk and into the cerebrospinal fluid (CSF). Saliva theophylline concentrations approximate unbound serum concentrations, but are not reliable for routine or therapeutic monitoring unless special techniques are used. An increase in the volume of distribution of theophylline, primarily due to reduction in plasma protein binding, occurs in premature neonates, patients with hepatic cirrhosis, uncorrected acidemia, the elderly and in women during the third trimester of pregnancy. In such cases, the patient may show signs of toxicity at total (bound + unbound) serum concentrations of theophylline in the therapeutic range (10-20 mcg/mL) due to elevated concentrations of the pharmacologically active unbound drug. Similarly, a patient with decreased theophylline binding may have a sub-therapeutic total drug concentration while the pharmacologically active unbound concentration is in the therapeutic range. If only total serum theophylline concentration is measured, this may lead to an unnecessary and potentially dangerous dose increase. In patients with reduced protein binding, measurement of unbound serum theophylline concentration provides a more reliable means of dosage adjustment than measurement of total serum theophylline concentration. Generally, concentrations of unbound theophylline should be maintained in the range of 6-12 mcg/mL.

Metabolism

Following oral dosing, theophylline does not undergo any measurable first-pass elimination. In adults and children beyond one year of age, approximately 90% of the dose is metabolized in the liver. Biotransformation takes place through demethylation to 1-methylxanthine and 3-methylxanthine and hydroxylation to 1,3-dimethyluric acid. 1-methylxanthine is further hydroxylated, by xanthine oxidase, to 1-methyluric acid. About 6% of a theophylline dose is N-methylated to caffeine. Theophylline demethylation to 3-methylxanthine is catalyzed by cytochrome P-450 1A2, while cytochromes P-450 2E1 and P-450 3A3 catalyze the hydroxylation to 1,3-dimethyluric acid. Demethylation to 1-methylxanthine appears to be catalyzed either by cytochrome P-450 1A2 or a closely related cytochrome. In neonates, the N-demethylation pathway is absent while the function of the hydroxylation pathway is markedly deficient. The activity of these pathways slowly increases to maximal levels by one year of age.

Caffeine and 3-methylxanthine are the only theophylline metabolites with pharmacologic activity. 3-methylxanthine has approximately one tenth the pharmacologic activity of theophylline and serum concentrations in adults with normal renal function are < 1 mcg/mL. In patients with end-stage renal disease, 3-methylxanthine may accumulate to concentrations that approximate the unmetabolized theophylline concentration. Caffeine concentrations are usually undetectable in adults regardless of renal function. In neonates, caffeine may accumulate to concentrations that approximate the unmetabolized theophylline concentration and thus, exert a pharmacologic effect.

Both the N-demethylation and hydroxylation pathways of theophylline biotransformation are capacity-limited. Due to the wide intersubject variability of the rate of theophylline metabolism, non-linearity of elimination may begin in some patients at serum theophylline concentrations < 10 mcg/mL. Since this non-linearity results in more than proportional changes in serum theophylline concentrations with changes in dose, it is advisable to make increases or decreases in dose in small increments in order to achieve desired changes in serum theophylline concentrations (see DOSAGE AND ADMINISTRATION, Table VI). Accurate prediction of dose-dependency of theophylline metabolism in patients a priori is not possible, but patients with very high initial clearance rates (i.e., low steady state serum theophylline concentrations at above average doses) have the greatest likelihood of experiencing large changes in serum theophylline concentration in response to dosage changes.

Excretion

In neonates, approximately 50% of the theophylline dose is excreted unchanged in the urine. Beyond the first three months of life, approximately 10% of the theophylline dose is excreted unchanged in the urine. The remainder is excreted in the urine mainly as 1,3-dimethyluric acid (35-40%), 1-methyluric acid (20-25%) and 3-methylxanthine (15-20%). Since little theophylline is excreted unchanged in the urine and since active metabolites of theophylline (i.e., caffeine, 3-methylxanthine) do not accumulate to clinically significant levels even in the face of end-stage renal disease, no dosage adjustment for renal insufficiency is necessary in adults and children > 3 months of age. In contrast, the large fraction of the theophylline dose excreted in the urine as unchanged theophylline and caffeine in neonates requires careful attention to dose reduction and frequent monitoring of serum theophylline concentrations in neonates with reduced renal function (see WARNINGS).

Serum Concentrations at Steady State

After multiple doses of theophylline, steady state is reached in 30–65 hours (average 40 hours) in adults. At steady state, on a dosage regimen with 6-hour intervals, the expected mean trough concentration is approximately 60% of the mean peak concentration, assuming a mean theophylline half-life of 8 hours. The difference between peak and trough concentrations is larger in patients with more rapid theophylline clearance. In patients with high theophylline clearance and half-lives of about 4-5 hours, such as children age 1 to 9 years, the trough serum theophylline concentration may be only 30% of peak with a 6-hour dosing interval. In these patients a slow release formulation would allow a longer dosing interval (8-12 hours) with a smaller peak/trough difference.

Name of the medicinal product

Teosona

Qualitative and quantitative composition

Choline Theophyllinate

Special warnings and precautions for use

Capsule; Solution, ElixirSubstance-powder; Sustained-release tabletsCapsule, Extended ReleaseWARNINGS Concurrent Illness

Theophylline should be used with extreme caution in patients with the following clinical conditions due to the increased risk of exacerbation of the concurrent condition:

Active peptic ulcer disease
Seizure disorders
Cardiac arrhythmias (not including bradyarrhythmias)

Conditions That Reduce Theophylline Clearance

There are several readily identifiable causes of reduced theophylline clearance. If the total daily dose

is not appropriately reduced in the presence of these risk factors, severe and potentially fatal theophylline toxicity can occur. Careful consideration must be given to the benefits and risks of theophylline use and the need for more intensive monitoring of serum theophylline concentrations in patients with the following risk factors

Age
Neonates (term and premature)
Children < 1 year
Elderly ( > 60 years)
Concurrent Diseases
Acute pulmonary edema
Congestive heart failure
Cor pulmonale
Fever; ≥ 102°F for 24 hours or more; or lesser temperature elevations for longer periods
Hypothyroidism
Liver disease; cirrhosis, acute hepatitis
Reduced renal function in infants < 3 months of age
Sepsis with multi-organ failure
Shock
Cessation of Smoking
Drug Interactions
Adding a drug that inhibits theophylline metabolism erythromycin, tacrine) or stopping a concurrently administered drug that enhances theophylline metabolism (e.g., carbamazepine, rifampin).
(see PRECAUTIONS: DRUG INTERACTIONS, Table II).

When Signs Or Symptoms Of Theophylline Toxicity Are Present

Whenever a patient receiving theophylline develops nausea or vomiting, particularly repetitive vomiting, or other signs or symptoms consistent with theophylline toxicity (even if another cause may be suspected), additional doses of theophylline should be withheld and aserum theophylline concentration measured immediately. Patients should be instructed not to continue any dosage that causes adverse effects and to withhold subsequent doses until the symptoms have resolved, at which time the clinician may instruct the patient to resume the drug at a lower dosage (see DOSAGE AND ADMINISTRATION, Dosing Guidelines, Table VI).

Dosage Increases

Increases in the dose of theophylline should not be made in response to an acute exacerbation of symptoms of chronic lung disease since theophylline provides little added benefit to inhaled beta - selective agonists and systemically administered corticosteroids in this circumstance and increases the risk of adverse effects. A peak steady state serum theophylline concentration should be measured before increasing the dose in response to persistent chronic symptoms to ascertain whether an increase in dose is safe. Before increasing the theophylline dose on the basis of a low serum concentration, the clinician should consider whether the blood sample was obtained at an appropriate time in relationship to the dose and whether the patient has adhered to the prescribed regimen (see PRECAUTIONS, Laboratory Tests).

As the rate of theophylline clearance may be dose-dependent (i.e., steady-state serum concentrations may increase disproportionately to the increase in dose), an increase in dose based upon a subtherapeutic serum concentration measurement should be conservative. In general, limiting dose increases to about 25% of the previous total daily dose will reduce the risk of unintended excessive increases in serum theophylline concentration (see DOSAGE AND ADMINISTRATION, Table VI).

PRECAUTIONS General

Careful consideration of the various interacting drugs and physiologic conditions that can alter theophylline clearance and require dosage adjustment should occur prior to initiation of theophylline therapy, prior to increases in theophylline dose, and during follow up (see WARNINGS). The dose of theophylline selected for initiation of therapy should be low and, if tolerated, increased slowly over a period of a week or longer with the final dose guided by monitoring serum theophylline concentrations and the patient's clinical response (see DOSAGE AND ADMINISTRATION, Table V).

Monitoring Serum Theophylline Concentrations

Serum theophylline concentration measurements are readily available and should be used to determine whether the dosage is appropriate. Specifically, the serum theophylline concentration should be measured as follows:

  1. When initiating therapy to guide final dosage adjustment after titration.
  2. Before making a dose increase to determine whether the serum concentration is sub-therapeutic in a patient who continues to be symptomatic.
  3. Whenever signs or symptoms of theophylline toxicity are present.
  4. Whenever there is a new illness, worsening of a chronic illness or a change in the patient's treatment regimen that may alter theophylline clearance (e.g., fever > 102°F sustained for ≥ 24 hours, hepatitis, or drugs listed in Table II are added or discontinued).

To guide a dose increase, the blood sample should be obtained at the time of the expected peak serum theophylline concentration; 1-2 hours after a dose at steady-state. For most patients, steady-state will be reached after 3 days of dosing when no doses have been missed, no extra doses have been added, and none of the doses have been taken at unequal intervals. A trough concentration (i.e., at the end of the dosing interval) provides no additional useful information and may lead to an inappropriate dose increase since the peak serum theophylline concentration can be two or more times greater than the trough concentration with an immediate-release formulation. If the serum sample is drawn more than two hours after the dose, the results must be interpreted with caution since the concentration may not be reflective of the peak concentration. In contrast, when signs or symptoms of theophylline toxicity are present, the serum sample should be obtained as soon as possible, analyzed immediately, and the result reported to the clinician without delay. In patients in whom decreased serum protein binding is suspected (e.g., cirrhosis, women during the third trimester of pregnancy), the concentration of unbound theophylline should be measured and the dosage adjusted to achieve an unbound concentration of 6-12 mcg/mL.

Saliva concentrations of theophylline cannot be used reliably to adjust dosage without special techniques.

Effects On Laboratory Tests

As a result of its pharmacological effects, theophylline at serum concentrations within the 10-20 mcg/mL range modestly increases plasma glucose (from a mean of 88 mg% to 98 mg%), uric acid (from a mean of 4 mg/dl to 6 mg/dl), free fatty acids (from a mean of 451 μeq/l to 800 μeq/l), total cholesterol (from a mean of 140 vs 160 mg/dl), HDL (from a mean of 36 to 50 mg/dl), HDL/LDL ratio (from a mean of 0.5 to 0.7), and urinary free cortisol excretion (from a mean of 44 to 63 mcg/24 hr). Theophylline at serum concentrations within the 10-20 mcg/mL range may also transiently decrease serum concentrations of triiodothyronine (144 before, 131 after one week and 142 ng/dl after 4 weeks of theophylline). The clinical importance of these changes should be weighed against the potential therapeutic benefit of theophylline in individual patients.

Carcinogenesis, Mutagenesis, and Impairment Of Fertility

Long term carcinogenicity studies have been carried out in mice (oral doses 30-150 mg/kg) and rats (oral doses 5-75 mg/kg). Results are pending.

Theophylline has been studied in Ames salmonella, in vivo and in vitro cytogenetics, micronucleus and Chinese hamster ovary test systems and has not been shown to be genotoxic.

In a 14 week continuous breeding study, theophylline, administered to mating pairs of B6C3F1 mice at oral doses of 120, 270 and 500 mg/kg (approximately 1.0-3.0 times the human dose on a mg/m² basis) impaired fertility, as evidenced by decreases in the number of live pups per litter, decreases in the mean number of litters per fertile pair, and increases in the gestation period at the high dose as well as decreases in the proportion of pups born alive at the mid and high dose.

In 13 week toxicity studies, theophylline was administered to F344 rats and B6C3F1 mice at oral doses of 40-300 mg/kg (approximately 2.0 times the human dose on a mg/m² basis). At the high dose, systemic toxicity was observed in both species including decreases in testicular weight.

Pregnancy

Category C: There are no adequate and well controlled studies in pregnant women. Additionally, there are no teratogenicity studies in non-rodents (e.g., rabbits). Theophylline was not shown to be teratogenic in CD-1 mice at oral doses up to 400 mg/kg, approximately 2.0 times the human dose on a mg/m basis or in CD-1 rats at oral doses up to 260 mg/kg, approximately 3.0 times the recommended human dose on a mg/m² basis. At a dose of 220 mg/kg, embryotoxicity was observed in rats in the absence of maternal toxicity.

Nursing Mothers

Theophylline is excreted into breast milk and may cause irritability or other signs of mild toxicity in nursing human infants. The concentration of theophylline in breast milk is about equivalent to the maternal serum concentration. An infant ingesting a liter of breast milk containing 10-20 mcg/mL of theophylline per day is likely to receive 10-20 mg of theophylline per day. Serious adverse effects in the infant are unlikely unless the mother has toxic serum theophylline concentrations.

Pediatric Use

Theophylline is safe and effective for the approved indications in pediatric patients (See INDICATIONS AND USAGE). The maintenance dose of theophylline must be selected with caution in pediatric patients since the rate of theophylline clearance is highly variable across the age range of neonates to adolescents (see CLINICAL PHARMACOLOGY, Table I, WARNINGS, and DOSAGE AND ADMINISTRATION, Table V). Due to the immaturity of theophylline metabolic pathways in infants under the age of one year, particular attention to dosage selection and frequent monitoring of serum theophylline concentrations are required when theophylline is prescribed to pediatric patients in this age group.

Geriatric Use

Elderly patients are at significantly greater risk of experiencing serious toxicity from theophylline than younger patients due to pharmacokinetic and pharmacodynamic changes associated with aging. Theophylline clearance is reduced in patients greater than 60 years of age, resulting in increased serum theophylline concentrations in response to a given theophylline dose. Protein binding may be decreased in the elderly resulting in a larger proportion of the total serum theophylline concentration in the pharmacologically active unbound form. Elderly patients also appear to be more sensitive to the toxic effects of theophylline after chronic overdosage than younger patients. For these reasons, the maximum daily dose of theophylline in patients greater than 60 years of age ordinarily should not exceed 400 mg/day unless the patient continues to be symptomatic and the peak steady state serum theophylline concentration is < 10 mcg/mL (see DOSAGE AND ADMINISTRATION). Theophylline doses greater than 400 mg/d should be prescribed with caution in elderly patients.

WARNINGS Concurrent Illness

Teosona should be used with extreme caution in patients with the following clinical conditions due to the increased risk of exacerbation of the concurrent condition:

Active peptic ulcer disease Seizure disorders Cardiac arrhythmias (not including bradyarrhythmias)

Conditions That Reduce Teosona Clearance

There are several readily identifiable causes of reduced Teosona clearance. If the infusion rate is not appropriately reduced in the presence of these risk factors, severe and potentially fatal Teosona toxicity can occur. Careful consideration must be given to the benefits and risks of Teosona use and the need for more intensive monitoring of serum Teosona concentrations in patients with the following risk factors:

Age

Neonates (term and premature) Children < 1 year Elderly ( > 60 years)

Concurrent Diseases

Acute pulmonary edema Congestive heart failure Cor-pulmonale Fever; ≥ 102°F for 24 hours or more; or lesser temperature elevations for longer periods Hypothyroidism Liver disease; cirrhosis, acute hepatitis Reduced renal function in infants < 3 months of age Sepsis with multi-organ failure Shock

Cessation of Smoking

Drug Interactions

Adding a drug that inhibits Teosona metabolism (e.g., cimetidine, erythromycin, tacrine) or stopping a concurrently administered drug that enhances Teosona metabolism (e.g., carbamazepine, rifampin). (See PRECAUTIONS: DRUG INTERACTIONS, Table ll.)

When Signs or Symptoms of Teosona Toxicity are Present

Whenever a patient receiving Teosona develops nausea or vomiting, particularly repetitive vomiting, or other signs or symptoms consistent with Teosona toxicity (even if another cause may be suspected), the intravenous infusion should be stopped and a serum Teosona concentration measured immediately.

Dosage Increases

Increases in the dose of intravenous Teosona should not be made in response to an acute exacerbation of symptoms unless the steady-state serum Teosona concentration is < 10 mcg/mL.

As the rate of Teosona clearance may be dose-dependent (i.e., steady-state serum concentrations may increase disproportionately to the increase in dose), an increase in dose based upon a sub-therapeutic serum concentration measurement should be conservative. In general, limiting infusion rate increases to about 25% of the previous infusion rate will reduce the risk of unintended excessive increases in serum Teosona concentration (see DOSAGE AND ADMINISTRATION, Table VI).

Solutions containing dextrose without electrolytes should not be administered simultaneously with blood through the same infusion set because of the possibility of agglomeration of erythrocytes.

The intravenous administration of these solutions may cause fluid overloading resulting in dilution of serum electrolyte concentrations, overhydration, congested states or pulmonary edema.

Because dosages of these drugs are titrated to response (see DOSAGE AND ADMINISTRATION), no additives should be made to Teosona in 5% Dextrose Injection USP.

PRECAUTIONS General

Careful consideration of the various interacting drugs and physiologic conditions that can alter Teosona clearance and require dosage adjustment should occur prior to initiation of Teosona therapy and prior to increases in Teosona dose (see WARNINGS).

Monitoring Serum Teosona Concentrations

Serum Teosona concentration measurements are readily available and should be used to determine whether the dosage is appropriate. Specifically, the serum Teosona concentration should be measured as follows:

  1. Before making a dose increase to determine whether the serum concentration is sub-therapeutic in a patient who continues to be symptomatic.
  2. Whenever signs or symptoms of Teosona toxicity are present.
  3. Whenever there is a new illness, worsening of an existing concurrent illness or a change in the patient's treatment regimen that may alter Teosona clearance (e.g., fever > 102°F sustained for ≥ 24 hours, hepatitis, or drugs listed in Table ll are added or discontinued).

In patients who have received no Teosona in the previous 24 hours, a serum concentration should be measured 30 minutes after completion of the intravenous loading dose to determine whether the serum concentration is < 10 mcg/mL indicating the need for an additional loading dose or > 20 mcg/mL indicating the need to delay starting the constant IV infusion. Once the infusion has begun, a second measurement should be obtained after one expected half life (e.g., approximately 4 hours in children age 1 to 9 years and 8 hours in non-smoking adults; see Table I for the expected half life in additional patient populations). The second measurement should be compared to the first to determine the direction in which the serum concentration has changed. The infusion rate can then be adjusted before steady state is reached in an attempt to prevent an excessive or sub-therapeutic Teosona concentration from being achieved.

If a patient has received Teosona in the previous 24 hours, the serum concentration should be measured before administering an intravenous loading dose to make sure that it is safe to do so. If a loading dose is not indicated (i.e., the serum Teosona concentration is ≥ 10 mcg/mL), a second measurement should be obtained as above at the appropriate time after starting the intravenous infusion. If, on the other hand, a loading dose is indicated (see DOSAGE AND ADMINISTRATION for guidance on selection of the appropriate loading dose), a second blood sample should be obtained after the loading dose and a third sample should be obtained one expected half-life after starting the constant infusion to determine the direction in which the serum concentration has changed.

Once the above procedures related to initiation of intravenous Teosona infusion have been completed, subsequent serum samples for determination of Teosona concentration should be obtained at 24-hour intervals for the duration of the infusion. The Teosona infusion rate should be increased or decreased as appropriate based on the serum Teosona levels.

When signs or symptoms of Teosona toxicity are present, the intravenous infusion should be stopped and a serum sample for Teosona concentration should be obtained as soon as possible, analyzed immediately, and the result reported to the clinician without delay. In patients in whom decreased serum protein binding is suspected (e.g., cirrhosis, women during the third trimester of pregnancy), the concentration of unbound Teosona should be measured and the dosage adjusted to achieve an unbound concentration of 6-12 mcg/mL.

Saliva concentrations of Teosona cannot be used reliably to adjust dosage without special techniques.

Clinical evaluation and periodic laboratory determinations are necessary to monitor changes in fluid balance, electrolyte concentrations, and acid-base balance during prolonged therapy or whenever the condition of the patient warrants such evaluation.

Do not use plastic container in series connection.

If administration is controlled by a pumping device, care must be taken to discontinue pumping action before the container runs dry or air embolism may result.

These solutions are intended for intravenous administration using sterile equipment. It is recommended that intravenous administration apparatus be replaced at least once every 24 hours.

Use only if solution is clear and container and seals are intact.

Effects on Laboratory Tests

As a result of its pharmacological effects, Teosona at serum concentrations within the 10-20 mcg/mL range modestly increases plasma glucose (from a mean of 88 mg% to 98 mg%), uric acid (from a mean of 4 mg/dl to 6 mg/dl), free fatty acids (from a mean of 451 µEq/L to 800 µEq/L, total cholesterol (from a mean of 140 vs 160 mg/dl), HDL (from a mean of 36 to 50 mg/dl), HDL/LDL ratio (from a mean of 0.5 to 0.7), and urinary free cortisol excretion (from a mean of 44 to 63 mcg/24 hr). Teosona at serum concentrations within the 10-20 mcg/mL range may also transiently decrease serum concentrations of triiodothyronine (144 before, 131 after one week and 142 ng/dl after 4 weeks of Teosona). The clinical importance of these changes should be weighed against the potential therapeutic benefit of Teosona in individual patients.

Carcinogenesis, Mutagenesis, and Impairment of Fertility

Long term carcinogenicity studies have been carried out in mice (oral doses 30-150 mg/kg) and rats (oral doses 5-75 mg/kg). Results are pending. Teosona has been studied in Ames salmonella, in vivo and in vitro cytogenetics, micronucleus and Chinese hamster ovary test systems and has not been shown to be genotoxic.

In a 14 week continuous breeding study, Teosona, administered to mating pairs of B6C3F1 mice at oral doses of 120, 270 and 500 mg/kg (approximately 1.0-3.0 times the human dose on a mg/m² basis) impaired fertility, as evidenced by decreases in the number of live pups per litter, decreases in the mean number of litters per fertile pair, and increases in the gestation period at the high dose as well as decreases in the proportion of pups born alive at the mid and high dose. In 13 week toxicity studies, Teosona was administered to F344 rats and B6C3F1 mice at oral doses of 40-300 mg/kg (approximately 2.0 times the human dose on a mg/m² basis). At the high dose, systemic toxicity was observed in both species including decreases in testicular weight.

Pregnancy

CATEGORY C: There are no adequate and well controlled studies in pregnant women. Additionally, there are no teratogenicity studies in non-rodents (e.g., rabbits). Teosona was not shown to be teratogenic in CD-1 mice at oral doses up to 400 mg/kg, approximately 2.0 times the human dose on a mg/m² basis or in CD-1 rats at oral doses up to 260 mg/kg, approximately 3.0 times the recommended human dose on a mg/m² basis. At a dose of 220 mg/kg, embryotoxicity was observed in rats in the absence of maternal toxicity.

Nursing Mothers

Teosona is excreted into breast milk and may cause irritability or other signs of mild toxicity in nursing human infants. The concentration of Teosona in breast milk is about equivalent to the maternal serum concentration. An infant ingesting a liter of breast milk containing 10-20 mcg/mL of Teosona per day is likely to receive 10-20 mg of Teosona per day. Serious adverse effects in the infant are unlikely unless the mother has toxic serum Teosona concentrations.

Pediatric Use

Teosona is safe and effective for the approved indications in pediatric patients (see INDICATIONS AND USAGE). The constant infusion rate of intravenous Teosona must be selected with caution in pediatric patients since the rate of Teosona clearance is highly variable across the age range of neonates to adolescents (see CLINICAL PHARMACOLOGY, Table I, WARNINGS, and DOSAGE AND ADMINISTRATION, Table V). Due to the immaturity of Teosona metabolic pathways in pediatric patients under the age of one year, particular attention to dosage selection and frequent monitoring of serum Teosona concentrations are required when Teosona is prescribed to pediatric patients in this age group.

Geriatric Use

Elderly patients are at significantly greater risk of experiencing serious toxicity from Teosona than younger patients due to pharmacokinetic and pharmacodynamic changes associated with aging. Teosona clearance is reduced in patients greater than 60 years of age, resulting in increased serum Teosona concentrations in response to a given Teosona infusion rate. Protein binding may be decreased in the elderly resulting in a larger proportion of the total serum Teosona concentration in the pharmacologically active unbound form. Elderly patients also appear to be more sensitive to the toxic effects of Teosona after chronic overdosage than younger patients. For these reasons, the maximum infusion rate of Teosona in patients greater than 60 years of age ordinarily should not exceed 17 mg/hr unless the patient continues to be symptomatic and the steady state serum Teosona concentration is < 10 mcg/mL (see DOSAGE AND ADMINISTRATION). Teosona infusion rate greater than 17 mg/hr should be prescribed with caution in elderly patients.

WARNINGS Concurrent Illness

Theophylline should be used with extreme caution in patients with the following clinical conditions due to the increased risk of exacerbation of the concurrent condition:

Active peptic ulcer disease
Seizure disorders
Cardiac arrhythmias (not including bradyarrhythmias)

Conditions That Reduce Theophylline Clearance

There are several readily identifiable causes of reduced theophylline clearance. If the total daily dose is not appropriately reduced in the presence of these risk factors, severe and potentially fatal theophylline toxicity can occur. Careful consideration must be given to the benefits and risks of theophylline use and the need for more intensive monitoring of serum theophylline concentrations in patients with the following risk factors:

Age

Neonates (term and premature)
Children < 1 year
Elderly ( > 60 years)

Concurrent Diseases

Acute pulmonary edema
Congestive heart failure
Cor-pulmonale
Fever; ≥ 102° F for 24 hours or more; or lesser temperature elevations for longer periods
Hypothyroidism
Liver disease; cirrhosis, acute hepatitis
Reduced renal function in infants < 3 months of age
Sepsis with multi-organ failure
Shock

Cessation of Smoking Drug Interactions

Adding a drug that inhibits theophylline metabolism (e.g., cimetidine, erythromycin, tacrine) or stopping a concurrently administered drug that enhances theophylline metabolism (e.g., carbamazepine, rifampin) (see PRECAUTIONS: DRUG INTERACTIONS, Table II).

When Signs or Symptoms of Theophylline Toxicity Are Present

Whenever a patient receiving theophylline develops nausea or vomiting, particularly repetitive vomiting, or other signs or symptoms consistent with theophylline toxicity (even if another cause may be suspected), additional doses of theophylline should be withheld and a serum theophylline concentration measured immediately. Patients should be instructed not to continue any dosage that causes adverse effects and to withhold subsequent doses until the symptoms have resolved, at which time the healthcare professional may instruct the patient to resume the drug at a lower dosage (see DOSAGE AND ADMINISTRATION, Dosing Guidelines, Table VI).

Dosage Increases

Increases in the dose of theophylline should not be made in response to an acute exacerbation of symptoms of chronic lung disease since theophylline provides little added benefit to inhaled Beta2 -selective agonists and systemically administered corticosteroids in this circumstance and increases the risk of adverse effects. A peak steady-state serum theophylline concentration should be measured before increasing the dose in response to persistent chronic symptoms to ascertain whether an increase in dose is safe. Before increasing the theophylline dose on the basis of a low serum concentration, the healthcare professional should consider whether the blood sample was obtained at an appropriate time in relationship to the dose and whether the patient has adhered to the prescribed regimen (see PRECAUTIONS, Laboratory Tests).

As the rate of theophylline clearance may be dose-dependent (i.e., steady-state serum concentrations may increase disproportionately to the increase in dose), an increase in dose based upon a sub-therapeutic serum concentration measurement should be conservative. In general, limiting dose increases to about 25% of the previous total daily dose will reduce the risk of unintended excessive increases in serum theophylline concentration (see DOSAGE AND ADMINISTRATION, Table VI).

PRECAUTIONS General

Careful consideration of the various interacting drugs and physiologic conditions that can alter theophylline clearance and require dosage adjustment should occur prior to initiation of theophylline therapy, prior to increases in theophylline dose, and during follow up (see WARNINGS). The dose of theophylline selected for initiation of therapy should be low and, if tolerated, increased slowly over a period of a week or longer with the final dose guided by monitoring serum theophylline concentrations and the patient's clinical response (see DOSAGE AND ADMINISTRATION, Table V).

Monitoring Serum Theophylline Concentrations

Serum theophylline concentration measurements are readily available and should be used to determine whether the dosage is appropriate. Specifically, the serum theophylline concentration should be measured as follows:

  1. When initiating therapy to guide final dosage adjustment after titration.
  2. Before making a dose increase to determine whether the serum concentration is sub-therapeutic in a patient who continues to be symptomatic.
  3. Whenever signs or symptoms of theophylline toxicity are present.
  4. Whenever there is a new illness, worsening of a chronic illness or a change in the patient's treatment regimen that may alter theophylline clearance (e.g., fever > 102°F sustained for ≥ 24 hours, hepatitis, or drugs listed in Table II are added or discontinued).

To guide a dose increase, the blood sample should be obtained at the time of the expected peak serum theophylline concentration; 12 hours after a dose at steady-state (expected peak serum theophylline concentration range is between 5 –15 mcg/mL). For most patients, steady-state will be reached after 3 days of dosing when no doses have been missed, no extra doses have been added, and none of the doses have been taken at unequal intervals. A trough concentration (i.e., at the end of the dosing interval) provides no additional useful information and may lead to an inappropriate dose increase since the peak serum theophylline concentration can be two or more times greater than the trough concentration with an extended-release formulation. If the serum sample is drawn more or less than twelve (12) hours after the dose, the results must be interpreted with caution since the concentration may not be reflective of the peak concentration. In contrast, when signs or symptoms of theophylline toxicity are present, the serum sample should be obtained as soon as possible, analyzed immediately, and the result reported to the healthcare professional without delay. In patients in whom decreased serum protein binding is suspected (e.g., cirrhosis, women during the third trimester of pregnancy), the concentration of unbound theophylline should be measured and the dosage adjusted to achieve an unbound concentration of 6-12 mcg/mL Saliva concentrations of theophylline cannot be used reliably to adjust dosage without special techniques.

Effects on Laboratory Tests

As a result of its pharmacological effects, theophylline at serum concentrations within the 10-20 mcg/mL range modestly increases plasma glucose (from a mean of 88 mg% to 98 mg%), uric acid (from a mean of 4 mg/dL to 6 mg/dL), free fatty acids (from a mean of 451 µEq/L to 800 µEq/L, total cholesterol (from a mean of 140 vs 160 mg/dL), HDL (from a mean of 36 to 50 mg/dL), HDL/LDL ratio (from a mean of 0.5 to 0.7), and urinary free cortisol excretion (from a mean of 44 to 63 mcg/24 hr). Theophylline at serum concentrations within the 10-20 mcg/mL range may also transiently decrease serum concentrations of tri-iodothyronine (144 before, 131 after one week and 142 ng/dL after 4 weeks of theophylline). The clinical importance of these changes should be weighed against the potential therapeutic benefit of theophylline in individual patients.

Carcinogenesis, Mutagenesis, and Impairment of Fertility

Long term carcinogenicity studies have been carried out in mice (oral doses 30-150 mg/kg) and rats (oral doses 5-75 mg/kg). Results are pending.

Theophylline has been studied in Ames salmonella, in vivo and in vitro cytogenetics, micronucleus and Chinese hamster ovary test systems and has not been shown to be genotoxic.

In a 14 week continuous breeding study, theophylline, administered to mating pairs of B6C3F1 mice at oral doses of 120, 270 and 500 mg/kg (approximately 1.0-3.0 times the human dose on a mg/m2 basis) impaired fertility, as evidenced by decreases in the number of live pups per litter, decreases in the mean number of litters per fertile pair, and increases in the gestation period at the high dose as well as decreases in the proportion of pups born alive at the mid and high dose. In 13 week toxicity studies, theophylline was administered to F344 rats and B6C3F1 mice at oral doses of 40-300 mg/kg (approximately 2.0 times the human dose on a mg/m2 basis). At the high dose, systemic toxicity was observed in both species including decreases in testicular weight.

Pregnancy Category C

In studies in which pregnant mice, rats and rabbits were dosed during the period of organogenesis, theophylline produced teratogenic effects.

In studies with mice, a single intraperitoneal dose at and above 100 mg/kg (approximately equal to the maximum recommended oral dose for adults on a mg/m2 basis) during organogenesis produced cleft palate and digital abnormalities. Micromelia, micrognathia, clubfoot, subcutaneous hematoma, open eyelids, and embryolethality were observed at doses that are approximately 2 times the maximum recommended oral dose for adults on a mg/m2 basis.

In a study with rats dosed from conception through organogenesis, an oral dose of 150 mg/kg/day (approximately 2 times the maximum recommended oral dose for adults on a mg/m2 basis) produced digital abnormalities. Embryolethality was observed with a subcutaneous dose of 200 mg/kg/day (approximately 4 times the maximum recommended oral dose for adults on a mg/m2 basis).

In a study in which pregnant rabbits were dosed throughout organogenesis, an intravenous dose of 60 mg/kg/day (approximately 2 times the maximum recommended oral dose for adults on a mg/m2 basis), which caused the death of one doe and clinical signs in others, produced cleft palate and was embryolethal. Doses at and above 15 mg/kg/day (less than the maximum recommended oral dose for adults on a mg/m2 basis) increased the incidence of skeletal variations.

There are no adequate and well-controlled studies in pregnant women. Theophylline should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

Theophylline is excreted into breast milk and may cause irritability or other signs of mild toxicity in nursing human infants. The concentration of theophylline in breast milk is about equivalent to the maternal serum concentration. An infant ingesting a liter of breast milk containing 10-20 mcg/mL of theophylline per day is likely to receive 10-20 mg of theophylline per day. Serious adverse effects in the infant are unlikely unless the mother has toxic serum theophylline concentrations.

Pediatric Use

Theophylline is safe and effective for the approved indications in pediatric patients (see INDICATIONS). The maintenance dose of theophylline must be selected with caution in pediatric patients since the rate of theophylline clearance is highly variable across the age range of neonates to adolescents (see CLINICAL PHARMACOLOGY, Table I, WARNINGS, and DOSAGE AND ADMINISTRATION, Table V). Due to the immaturity of theophylline metabolic pathways in infants under the age of one year, particular attention to dosage selection and frequent monitoring of serum theophylline concentrations are required when theophylline is prescribed to pediatric patients in this age group.

Geriatric Use

Elderly patients are at a significantly greater risk of experiencing serious toxicity from theophylline than younger patients due to pharmacokinetic and pharmacodynamic changes associated with aging. The clearance of theophylline is decreased by an average of 30% in healthy elderly adults ( > 60 yrs) compared to healthy young adults. Theophylline clearance may be further reduced by concomitant diseases prevalent in the elderly, which further impair clearance of this drug and have the potential to increase serum levels and potential toxicity. These conditions include impaired renal function, chronic obstructive pulmonary disease, congestive heart failure, hepatic disease and an increased prevalence of use of certain medications (see PRECAUTIONS: DRUG INTERACTIONS) with the potential for pharmacokinetic and pharmacodynamic interaction. Protein binding may be decreased in the elderly resulting in an increased proportion of the total serum theophylline concentration in the pharmacologically active unbound form. Elderly patients also appear to be more sensitive to the toxic effects of theophylline after chronic overdosage than younger patients. Careful attention to dose reduction and frequent monitoring of serum theophylline concentrations are required in elderly patients (see PRECAUTIONS, Monitoring Serum Theophylline Concentrations, and DOSAGE AND ADMINISTRATION). The maximum daily dose of theophylline in patients greater than 60 years of age ordinarily should not exceed 400 mg/day unless the patient continues to be symptomatic and the peak steady-state serum theophylline concentration is < 10 mcg/mL (see DOSAGE AND ADMINISTRATION). Theophylline doses greater than 400 mg/d should be prescribed with caution in elderly patients.

Dosage (Posology) and method of administration

Capsule; Solution, ElixirSubstance-powder; Sustained-release tabletsCapsule, Extended ReleaseGeneral Considerations

The steady-state peak serum theophylline concentration is a function of the dose, the dosing interval, and the rate of theophylline absorption and clearance in the individual patient. Because of marked individual differences in the rate of theophylline clearance, the dose required to achieve a peak serum theophylline concentration in the 10-20 mcg/mL range varies fourfold among otherwise similar patients in the absence of factors known to alter theophylline clearance (e.g., 400-1600 mg/day in adults < 60 years old and 10-36 mg/kg/day in children 1-9 years old). For a given population there is no single theophylline dose that will provide both safe and effective serum concentrations for all patients. Administration of the median theophylline dose required to achieve a therapeutic serum theophylline concentration in a given population may result in either sub-therapeutic or potentially toxic serum theophylline concentrations in individual patients. For example, at a dose of 900 mg/d in adults < 60 years or 22 mg/kg/d in children 1-9 years, the steady state peak serum theophylline concentration will be < 10 mcg/mL in about 30% of patients, 10-20 mcg/mL in about 50% and 20-30 mcg/mL in about 20% of patients. The dose of theophylline must be individualized on the bas is of peak serum theophylline concentration measurements in order to achieve a dos e that will provide maximum potential benefit with minimal risk to adverse effects.

Transient caffeine-like adverse effects and excessive serum concentrations in slow metabolizers can be avoided in most patients by starting with a sufficiently low dose and slowly increasing the dose, if judged to be clinically indicated, in small increments (See Table V). Dose increases should only be made if the previous dosage is well tolerated and at intervals of no less than 3 days to allow serum theophylline concentrations to reach the new steady state. Dosage adjustment should be guided by serum theophylline concentration measurement (see PRECAUTIONS, Laboratory Tests and DOSAGE AND ADMINISTRATION, Table VI). Health care providers should instruct patients and care givers to discontinue any dosage that causes adverse effects, to withhold the medication until these symptoms are gone and to then resume therapy at a lower, previously tolerated dosage (see WARNINGS).

If the patient's symptoms are well controlled, there are no apparent adverse effects, and no intervening factors that might alter dosage requirements (see WARNINGS and PRECAUTIONS), serum theophylline concentrations should be monitored at 6 month intervals for rapidly growing children and at yearly intervals for all others. In acutely ill patients, serum theophylline concentrations should be monitored at frequent intervals, e.g., every 24 hours.

Theophylline distributes poorly into body fat, therefore, mg/kg dose should be calculated on the basis of ideal body weight.

Table V contains theophylline dosing titration schema recommended for patients in various age groups and clinical circumstances. Table VI contains recommendations for theophylline dosage adjustment based upon serum theophylline concentrations. Application of these general dosing recommendations to individual patients must take into account the unique clinical characteristics of each patient. In general, these recommendations should serve as the upper limit for dos age adjustments in order to decrease the risk of potentially serious adverse events associated with unexpected large increases in serum theophylline concentration.

Table V: Dosing initiation and titration (as anhydrous theophylline).*

A. Infants < 1 year old.

1. Initial Dosage.

  1. Premature Neonates:
    1. < 24 days postnatal age; 1.0 mg/kg every 12 hr
    2. ≥ 24 days postnatal age; 1.5 mg/kg every 12 hr
  2. Full term infants and infants up to 52 weeks of age:
  3. Total daily dose (mg) = [(0.2 x age in weeks)+5.0] x (Kg body Wt).
    1. up to age 26 weeks; divide dose into 3 equal amounts administered at 8 hour intervals.
    2. > 26 weeks of age; divide dose into 4 equal amounts administered at 6 hour intervals.

2. Final Dosage.

Adjusted to maintain a peak steady state serum theophylline concentration of 5-10 mcg/ml in neonates and 10-15 mcg/mL in older infants (see Table VI). Since the time required to reach steady-state is a function of theophylline half-life, up to 5 days may be required to achieve steady state in a premature neonate while only 2-3 days may be required in a 6 month old infant without other risk factors for impaired clearance in the absence of a loading dose. If a serum theophylline concentration is obtained before steady state is achieved, the maintenance dose should not be increased, even if the serum theophylline concentration is < 10 mcg/mL.

B. Children (1-15 years ) and adults (16-60 years ) without ris k factors for impaired clearance.

Titration Step Children < 45 kg Children > 45 kg and adults
1. Starting Dosage 12-14 mg/kg/day up to a maximum of 300 mg/day divided Q4-6 hrs* 300 mg/day divided Q6-8 hrs*
2. After 3 days, if tolerated, increase dose to: 16 mg/kg/day up to a maximum of 400 mg/day divided Q4-6 hrs* 400 mg/day divided Q6-8 hrs*
3. After 3 more days, if tolerated, increase dose to: 20 mg/kg/day up to a maximum o f 600 mg /day divided Q4-6 hrs* 600 mg/day divided Q6-8 hrs*

C. Patients With Risk Factors For Impaired Clearance, The Elderly ( > 60 Years ), And Thos e In Whom It Is Not Feasible To Monitor Serum Theophylline Concentrations

In children 1-15 years of age, the final theophylline dose should not exceed 16 mg/kg/day up to a maximum of 400 mg/day in the presence of risk factors for reduced theophylline clearance (see WARNINGS) or if it is not feasible to monitor serum theophylline concentrations.

In adolescents ≥ 16 years and adults, including the elderly, the final theophylline dose should not exceed 400 mg/day in the presence of risk factors for reduced theophylline clearance (see WARNINGS) or if it is not feasible to monitor serum theophylline concentrations.

D. Loading Dose for Acute Bronchodilatation

An inhaled beta-2 selective agonist, alone or in combination with a systemically administered corticosteroid, is the most effective treatment for acute exacerbations of reversible airways obstruction. Theophylline is a relatively weak bronchodilator, is less effective than an inhaled beta-2 selective agonist and provides no added benefit in the treatment of acute bronchospasm. If an inhaled or parenteral beta agonist is not available, a loading dose of an oral immediate release theophylline can be used as a temporary measure. A single 5 mg/kg dose of theophylline, in a patient who has not received any theophylline in the previous 24 hours, will produce an average peak serum theophylline concentration of 10 mcg/mL (range 5-15 mcg/mL). If dosing with theophylline is to be continued beyond the loading dose, the guidelines in Sections A.1.b., B.3, or C., above, should be utilized and serum theophylline concentration monitored at 24 hour intervals to adjust final dosage.

* Patients with more rapid metabolism, clinically identified by higher than average dose requirements, should receive a smaller dose more frequently to prevent breakthrough symptoms resulting from low trough concentrations before the next dose. A reliably absorbed slow-release formulation will decrease fluctuations and permit longer dosing intervals.

Table VI: Dosage adjustment guided by serum theophylline concentration

Peak Serum Concentration Dosage Adjustment
< 9.9 mcg/mL If symptoms are not controlled and current dosage is tolerated, increase dose about 25%. Recheck serum concentration after three days for further dosage adjustment.
10 to 14.9 mcg/mL If symptoms are controlled and current dosage is tolerated, maintain dose and recheck serum concentration at 6-12 month intervals.¶ If symptoms are not controlled and current dosage is tolerated consider adding additional medication(s) to treatment regimen.
15-19.9 mcg/mL Consider 10% decrease in dose to provide greater margin of safety even if current dosage is tolerated¶
20-24.9 mcg/mL Decrease dose by 25% even if no adverse effects are present. Recheck serum concentration after 3 days to guide further dosage adjustment.
25-30 mcg/mL Skip next dose and decrease subsequent doses at least 25% even if no adverse effects are present. Recheck serum concentration after 3 days to guide further dosage adjustment. If symptomatic, consider whether overdose treatment is indicated (see recommendations for chronic OVERDOSAGE).
> 30 mcg/mL Treat overdose as indicated (see recommendations for chronic overdosage). If theophylline is subsequently resumed, decrease dose by at least 50% and recheck serum concentration after 3 days to guide further dosage adjustment.
¶ Dose reduction and/or serum theophylline concentration measurement is indicated whenever adverse effects are present, physiologic abnormalities that can reduce theophylline clearance occur (e.g., sustained fever), or a drug that interacts with theophylline is added or discontinued (see WARNINGS).

These solutions are for intravenous use only.

General Considerations

The steady-state serum Teosona concentration is a function of the infusion rate and the rate of Teosona clearance in the individual patient. Because of marked individual differences in the rate of Teosona clearance, the dose required to achieve a serum Teosona concentration in the 10-20 mcg/mL range varies fourfold among otherwise similar patients in the absence of factors known to alter Teosona clearance. For a given population there is no single Teosona dose that will provide both safe and effective serum concentrations for all patients. Administration of the median Teosona dose required to achieve a therapeutic serum Teosona concentration in a given population may result in either sub-therapeutic or potentially toxic serum Teosona concentrations in individual patients. The dose of Teosona must be individualized on the basis of serum Teosona concentration measurements in order to achieve a dose that will provide maximum potential benefit with minimal risk of adverse effects.

When Teosona is used as an acute bronchodilator, the goal of obtaining a therapeutic serum concentration is best accomplished with an intravenous loading dose. Because of rapid distribution into body fluids, the serum concentration (C) obtained from an initial loading dose (LD) is related primarily to the volume of distribution (V), the apparent space into which the drug diffuses:

C=LD/V

If a mean volume of distribution of about 0.5 L/kg is assumed (actual range is 0.3 to 0.7 L/kg), each mg/kg (ideal body weight) of Teosona administered as a loading dose over 30 minutes results in an average 2 mcg/mL increase in serum Teosona concentration.

Therefore, in a patient who has received no Teosona in the previous 24 hours, a loading dose of intravenous Teosona of 4.6 mg/kg, calculated on the basis of ideal body weight and administered over 30 minutes, on average, will produce maximum post-distribution serum concentration of 10 mcg/mL with a range of 6-16 mcg/mL. When a loading dose becomes necessary in the patient who has already received Teosona, estimation of the serum concentration based upon the history is unreliable, and an immediate serum level determination is indicated. The loading dose can then be determined as follows:

D=(Desired C-Measured C) (V)

Where D is the loading dose, C is the serum Teosona concentration, and V is the volume of distribution. The mean volume of distribution can be assumed to be 0.5 L/kg and the desired serum concentration should be conservative (e.g., 10 mcg/mL) to allow for the variability in the volume of distribution. A loading dose should not be given before obtaining a serum Teosona concentration if the patient has received any Teosona in the previous 24 hours.

A serum concentration obtained 30 minutes after an intravenous loading dose, when distribution is complete, can be used to assess the need for and size of subsequent loading doses, if clinically indicated, and for guidance of continuing therapy. Once a serum concentration of 10 to 15 mcg/mL has been achieved with the use of a loading dose(s), a constant intravenous infusion is started. The rate of administration is based upon mean pharmacokinetic parameters for the population and calculated to achieve a target serum concentration of 10 mcg/mL (see Table V). For example, in non-smoking adults, initiation of a constant intravenous Teosona infusion of 0.4 mg/kg/hr at the completion of the loading dose, on average, will result in a steady-state concentration of 10 mcg/mL with a range of 7-26 mcg/mL. The mean and range of steady-state serum concentrations are similar when the average child (age 1 to 9 years) is given a loading dose of 4.6 mg/kg Teosona followed by a constant intravenous infusion of 0.8 mg/kg/hr. Since there is large interpatient variability in Teosona clearance, serum concentrations will rise or fall when the patient's clearance is significantly different from the mean population value used to calculate the initial infusion rate. Therefore, a second serum concentration should be obtained one expected half life after starting the constant infusion (e.g., approximately 4 hours for children age 1 to 9 and 8 hours for nonsmoking adults; see Table I for the expected half-life in additional patient populations) to determine if theconcentration is accumulating or declining from the post loading dose level. If the level isdeclining as a result of a higher than average clearance, an additional loading dose can be administered and/or the infusion rate increased. In contrast, if the second sample demonstrates a higher level, accumulation of the drug can be assumed, and the infusion rate should be decreased before the concentration exceeds 20 mcg/mL. An additional sample is obtained 12 to 24 hours later to determine if further adjustments are required and then at 24-hour intervals to adjust for changes, if they occur. This empiric method, based upon mean pharmacokinetic parameters, will prevent large fluctuations in serum concentration during the most critical period of the patient's course.

In patients with cor pulmonale, cardiac decompensation, or liver dysfunction, or in those aking drugs that markedly reduce Teosona clearance (e.g., cimetidine), the initial Teosona infusion rate should not exceed 17 mg/hr unless serum concentrations can be monitored at 24-hour intervals. In these patients, 5 days may be required before steady-state is reached.

Teosona distributes poorly into body fat, therefore, mg/kg dose should be calculated on the basis of ideal body weight. Table V contains initial Teosona infusion rates following an appropriate loading dose recommended for patients in various age groups and clinical circumstances. Table VI contains recommendations for final Teosona dosage adjustment based upon serum Teosona concentrations. Application of these general dosing recommendations to individual patients must take into account the unique clinical characteristics of each patient. In general, these recommendations should serve as the upper limit for dosage adjustments in order to decrease the risk of potentially serious adverse events associated with unexpected large increases in serum Teosona concentration.

Table V. Initial Teosona infusion rates following an appropriate loading dose.

Patient population Age Teosona infusion rate
(mg/kg/hr)*†
Neonates Postnatal age up to 24 days 1 mg/kg q12h/‡
Postnatal age beyond 24 days 1.5 mg/kg q12h/‡
Infants 6-52 we eks old mg/kg/hr=(0.008) (age in weeks) + 0.21
Young children 1-9 years 0.8
Older children 9-12 ye ars 0.7
Adolescents or marijuana 12-16 years 0.7
Adolescents 12-16 years 0.5§
Adults (otherwise healthy nonsmokers) 16-60 years 0.4§
ElderlyCardiac decompensation, cor pulmonale, liver dysfunction, sepsis with multi-organ failure, or shock > 60 years 0.3¶
0.2¶
* To achieve a target concentration of 10 mcg/mL. Aminophylline = Teosona/0.8. Use ideal body weight for obese patients.
† Lower initial dosage may be required for patients receiving other drugs that decrease Teosona clearance (e.g., cimetidine).
‡ To achieve a target concentration of 7.5 mcg/mL for neonatal apnea.
§ Not to exceed 900 mg/day, unless serum levels indicate the need for a larger dose.
¶ Not to exceed 400 mg/day, unless serum levels indicate the need for a larger dose.

Table VI. Final dosage adjustment guided by serum Teosona concentration.

Peak Serum Concentration Dosage Adjustment
< 9.9 mcg/mL If symptoms are not controlled and current dosage is tolerated, increase infusion rate about 25%. Recheck serum concentration after 12 hours in pediatric patients and 24 hours in adults for further dosage adjustment.
10 to 14.9 mcg/mL If symptoms are controlled and current dosage is tolerated, maintain infusion rate and recheck serum concentration at 24 hours intervals.¶ If symptoms are not controlled and current dosage is tolerated consider adding additional medication(s) to treatment regimen.
15-19.9 mcg/m L Consider 10% decrease in infusion rate to provide greater margin of safety even if current dosage is tolerated.¶
20-24.9 mcg/m L Decrease infusion rate by 25% even if no adverse effects are present. Recheck serum concentration after 12 hours in pediatric patients and 24 hours in adults to guide further dosage adjustment.
25-30 mcg/mL Stop infusion for 12 hours in pediatric patients and 24 hours in adults and decrease subsequent infusion rate a least 25% even if no adverse effects are present. Recheck serum concentration after 12 hours in pediatric patients and 24 hours in adults to guide further dosage adjustment. If symptomatic, stop infusion and consider whether overdose treatment is indicated (see recommendations for Chronic Overdosage).
> 30 mc g/mL Stop the infusion and treat overdose as indicated (see recommendations for Chronic Overdosage). If Teosona is subsequently resumed, decrease infusion rate by at least 50% and recheck serum concentration after 12 hours in pediatric patients and 24 hours in adults to guide further dosage adjustment.
¶ Dose reduction and/or serum Teosona concentration measurement is indicated whenever adverse effects are present, physiologic abnormalities that can reduce Teosona clearance occur (e.g., sustained fever), or a drug that interacts with Teosona is added or discontinued (see WARNINGS).

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

General Considerations

Teosona (theophylline anhydrous capsule) ®, like other extended-release theophylline products, is intended for patients with relatively continuous or recurring symptoms who have a need to maintain therapeutic serum levels of theophylline. It is not intended for patients experiencing an acute episode of bronchospasm (associated with asthma, chronic bronchitis, or emphysema). Such patients require rapid relief of symptoms and should be treated with an immediate-release or intravenous theophylline preparation (or other bronchodilators) and not with extended-release products.

Patients who metabolize theophylline at a normal or slow rate are reasonable candidates for once-daily dosing with Teosona (theophylline anhydrous capsule) ®. Patients who metabolize theophylline rapidly (e.g., the young, smokers, and some nonsmoking adults) and who have symptoms repeatedly at the end of a dosing interval, will require either increased doses given once a day or preferably, are likely to be better controlled by a schedule of twice-daily dosing. Those patients who require increased daily doses are more likely to experience relatively wide peak-trough differences and may be candidates for twice-a-day dosing with Teosona (theophylline anhydrous capsule) ®.

Patients should be instructed to take this medication each morning at approximately the same time and not to exceed the prescribed dose.

Recent studies suggest that dosing of extended-release theophylline products at night (after the evening meal) results in serum concentrations of theophylline which are not identical to those recorded during waking hours and may be characterized by early trough and delayed peak levels. This appears to occur whether the drug is given as an immediate-release, extended-release, or intravenous product. To avoid this phenomenon when two doses per day are prescribed, it is recommended that the second dose be given 10 to 12 hours after the morning dose and before the evening meal.

Food and posture, along with changes associated with circadian rhythm, may influence the rate of absorption and/or clearance rates of theophylline from extended-release dosage forms administered at night. The exact relationship of these and other factors to nighttime serum concentrations and the clinical significance of such findings require additional study. Therefore, it is not recommended that

Teosona (theophylline anhydrous capsule) ® (when used as a once-a-day product) be administered at night.

Patients who require a relatively high dose of theophylline (i.e., a dose equal to or greater than 900 mg or 13 mg/kg, whichever is less) should not take Teosona (theophylline anhydrous capsule) ® less than 1 hour before a high-fat-content meal since this may result in a significant increase in peak serum level and in the extent of absorption of theophylline as compared to administration in the fasted state (see PRECAUTIONS, Drug/Food Interactions).

The steady-state peak serum theophylline concentration is a function of the dose, the dosing interval, and the rate of theophylline absorption and clearance in the individual patient. Because of marked individual differences in the rate of theophylline clearance, the dose required to achieve a peak serum theophylline concentration in the 10-20 mcg/mL range varies fourfold among otherwise similar patients in the absence of factors known to alter theophylline clearance (e.g., 400-1600 mg/day in adults < 60 years old and 10-36 mg/kg/day in children 1-9 years old). For a given population there is no single theophylline dose that will provide both safe and effective serum concentrations for all patients. Administration of the median theophylline dose required to achieve a therapeutic serum theophylline concentration in a given population may result in either sub-therapeutic or potentially toxic serum theophylline concentrations in individual patients. For example, at a dose of 900 mg/day in adults < 60 years or 22 mg/kg/day in children 1-9 years, the steady-state peak serum theophylline concentration will be < 10 mcg/mL in about 30% of patients, 10-20 mcg/mL in about 50% and 20-30 mcg/mL in about 20% of patients. The dose of theophylline must be individualized on the basis of peak serum theophylline concentration measurements in order to achieve a dose that will provide maximum potential benefit with minimal risk of adverse effects.

Transient caffeine-like adverse effects and excessive serum concentrations in slow metabolizers can be avoided in most patients by starting with a sufficiently low dose and slowly increasing the dose, if judged to be clinically indicated, in small increments (See Table V). Dose increases should only be made if the previous dosage is well tolerated and at intervals of no less than 3 days to allow serum theophylline concentrations to reach the new steady state. Dosage adjustment should be guided by serum theophylline concentration measurement (see PRECAUTIONS, Laboratory Tests and DOSAGE AND ADMINISTRATION, Table VI). Health care providers should instruct patients and care givers to discontinue any dosage that causes adverse effects, to withhold the medication until these symptoms are gone and to then resume therapy at a lower, previously tolerated dosage (see WARNINGS).

If the patient's symptoms are well controlled, there are no apparent adverse effects, and no intervening factors that might alter dosage requirements (see WARNINGS and PRECAUTIONS), serum theophylline concentrations should be monitored at 6 month intervals for rapidly growing children and at yearly intervals for all others. In acutely ill patients, serum theophylline concentrations should be monitored at frequent intervals, e.g., every 24 hours.

Theophylline distributes poorly into body fat, therefore, mg/kg dose should be calculated on the basis of ideal body weight. Table V contains theophylline dosing titration schema recommended for patients in various age groups and clinical circumstances. Table VI contains recommendations for theophylline dosage adjustment based upon serum theophylline concentrations. Application of these general dosing recommendations to individual patients must take into account the unique clinical characteristics of each patient. In general, these recommendations should serve as the upper limit for dosage adjustments in order to decrease the risk of potentially serious adverse events associated with unexpected large increases in serum theophylline concentration.

Table V. Dosing initiation and titration (as anhydrous theophylline).*

A. Children (12-15 years) and adults (16-60 years) without risk factors for impaired clearance.
Titration Step Children < 45 kg Children > 45 kg and adults
1. Starting Dosage 12-14 mg/kg/day up to a maximum of 300 mg/day divided Q 24 hrs* 300-400 mg/day1 divided Q 24 hrs*
2. After 3 days, if tolerated, increase dose to: 16 mg/kg/day up to a maximum of 400 mg/day divided Q 24 hrs* 400-600 mg/day1 divided Q 24 hrs*
3. After 3 more days, if tolerated and if needed, increase dose to: 20 mg/kg/day up to a maximum of 600 mg/day divided Q 24 hrs* As with all theophylline products, doses greater than 600 mg should be titrated according to blood level (see Table VI)
1 If caffeine-like adverse effects occur, then consideration should be given to a lower dose and titrating the dose more slowly (see ADVERSE REACTIONS).

B. Patients with risk factors for impaired clearance, the elderly ( > 60 Years), and those in whom it is not feasible to monitor serum theophylline concentrations:

In children 12-15 years of age, the final theophylline dose should not exceed 16 mg/kg/day up to a maximum of 400 mg/day in the presence of risk factors for reduced theophylline clearance (see WARNINGS) or if it is not feasible to monitor serum theophylline concentrations.

In adolescents ≥ 16 years and adults, including the elderly, the final theophylline dose should not exceed 400 mg/day in the presence of risk factors for reduced theophylline clearance (see WARNINGS) or if it is not feasible to monitor serum theophylline concentrations.

* Patients with more rapid metabolism, clinically identified by higher than average dose requirements, should receive a smaller dose more frequently to prevent breakthrough symptoms resulting from low trough concentrations before the next dose. A reliably absorbed slow-release formulation will decrease fluctuations and permit longer dosing intervals.

Table VI. Dosage adjustment guided by serum theophylline concentration.

Peak Serum Concentration Dosage Adjustment
< 9.9 mcg/mL If symptoms are not controlled and current dosage is tolerated, increase dose about 25%. Recheck serum concentration after three days for further dosage adjustment.
10-14.9 mcg/mL If symptoms are controlled and current dosage is tolerated, maintain dose and recheck serum concentration at 6-12 month intervals.¶ If symptoms are not controlled and current dosage is tolerated consider adding additional medication(s) to treatment regimen.
15-19.9 mcg/mL Consider 10% decrease in dose to provide greater margin of safety even if current dosage is tolerated.¶
20-24.9 mcg/mL Decrease dose by 25% even if no adverse effects are present. Recheck serum concentration after 3 days to guide further dosage adjustment.
25-30 mcg/mL Skip next dose and decrease subsequent doses at least 25% even if no adverse effects are present. Recheck serum concentration after 3 days to guide further dosage adjustment. If symptomatic, consider whether overdosage treatment is indicated (see recommendations for chronic overdosage).
> 30 mcg/mL Treat overdose as indicated (see recommendations for chronic overdosage). If theophylline is subsequently resumed, decrease dose by at least 50% and recheck serum concentration after 3 days to guide further dosage adjustment.
¶ Dose reduction and/or serum theophylline concentration measurement is indicated whenever adverse effects are present, physiologic abnormalities that can reduce theophylline clearance occur (e.g., sustained fever), or a drug that interacts with theophylline is added or discontinued (see WARNINGS).