Overdosage produces acute respiratory depression, hypotension, circulatory failure and apnoea. Treatment must be artificial ventilation, lowering of the patient's head and infusion of plasma volume expanders.
Bensulf (thiopental sodium)
Overdosage may occur from too rapid or repeated injections. Too rapid injection may be followed by an alarming fall in blood pressure even to shock levels. Apnea, occasional laryngospasm, coughing and other respiratory difficulties with excessive or too rapid injections may occur. In the event of suspected or apparent overdosage, the drug should be discontinued, a patent airway established (intubate if necessary) or maintained, and oxygen should be administered, with assisted ventilation if necessary. The lethal dose of barbiturates varies and cannot be stated with certainty. Lethal blood levels may be as low as 1 mg/100 mL for short-acting barbiturates; less if other depressant drugs or alcohol are also present.
MANAGEMENT OF 0VERDOSAGE
It is generally agreed that respiratory depression or arrest due to unusual sensitivity to thiopental sodium or overdosage is easily managed if there is no concomitant respiratory obstruction. If the airway is patent, any method of ventilating the lungs (that prevents hypoxia) should be successful in maintaining other vital functions. Since depression of respiratory activity is one of the characteristic actions of the drug, it is important to observe respiration closely.
Should laryngeal spasm occur, it may be relieved by one of the usual methods, such as the use of a relaxant drug or positive pressure oxygen. Endotracheal intubation may be indicated in difficult cases.
Diluents in Bensulf (thiopental sodium) ® Kits
Ready-To-Mix Syringes and VialsUsed as diluents for preparing solutions of Bensulf (Thiopental Sodium for Injection, USP) the small volumes of administered fluid (from Sterile Water for Injection in bottles and vials) and amounts of sodium chloride (from 0.9% Sodium Chloride Injection in Ready-to-Mix Syringes) are unlikely to pose a threat of fluid or sodium chloride overload.
Bensulf sodium is contra-indicated in respiratory obstruction, acute asthma, severe shock and dystrophia myotonica. Administration of any barbiturate is contra-indicated in porphyria.
Care should also be exercised with severe cardiovascular diseases, severe respiratory diseases and hypertension of various aetiology.
Patients with hypersensitivity reactions to barbiturates.
Absolute Contraindications
Relative Contraindications
Diluents in Bensulf (thiopental sodium) ® Kits
Ready-To-Mix Syringes and Vials
(For preparing solutions of Thiopental Sodium for Injection, USP)
Do not use unless the diluent is clear and the bottle or vial seal or syringe package is undamaged.
Diluents in Bensulf (thiopental sodium) Kits, Ready-to-Mix Syringes or Vials should not be used for fluid or sodium chloride replacement.
Solutions of Bensulf sodium injection have a pH of 10 to 11 and are strongly alkaline in order to maintain stability. Solutions are incompatible with acid, acidic salts and solutions such as pethidine, morphine and promethazine.
Summary of the safety profile
Laryngeal spasm may occur, together with coughing or sneezing, during the induction procedure. For this reason it is not advised to use Bensulf sodium alone for peroral endoscopy.
A fall in blood pressure is often seen when Bensulf sodium is first given.
Although frequencies established in controlled clinical trials are not available for Bensulf sodium, the following are known to be relatively common in patients post general anaesthesia: drowsiness; nausea, with or without vomiting; decreased appetite; malaise; fatigue; dizziness; headache; and delirium in elderly patients.
Excessive doses are associated with hypothermia and profound cerebral impairment.
Tabulated summary of adverse reactions
Adverse reactions from literature searches, the KKI database and spontaneous reports with Bensulf sodium are listed in the table below.
Within the system organ class, the adverse reactions are listed by frequency using the following convention: very common (>1/10); common (>1/100 to <1/10); uncommon (>1/1,000 to <1/100); rare (>1/10,000 to <1/1,000); very rare (<1/10,000) and not known (cannot be estimated from the available data).
| System Organ Class | Adverse reaction | Frequency |
| Immune system disorder | Hypersensitivity, anaphylactic and anaphylactoid reactions | Not known |
| Metabolism and nutrition disorders | Decreased appetite, hypokalaemia, hyperkalaemia | Not known |
| Psychiatric disorders | Delirium, confusional state | Not known |
| Nervous system disorders | Cerebral impairment, amnesia, dizziness, somnolence, headache | Not known |
| Cardiac disorders | Myocardial depression, arrhythmia | Not known |
| Vascular disorders | Hypotension, circulatory collapse | Not known |
| Respiratory, thoracic and mediastinal disorders | Bronchospasm, respiratory depression, laryngospasm, cough, sneezing, apnoea | Not known |
| Gastrointestinal disorders | Nausea, vomiting | Not known |
| Skin and subcutaneous tissue disorders | Skin reaction | Not known |
| General disorders and administration site conditions | Malaise, fatigue, chills, extravasation, hypothermia | Not known |
| Investigations | Cardiac output decreased, blood pressure decreased | Not known |
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard
Bensulf (thiopental sodium)
Adverse reactions include respiratory depression, myocardial depression, cardiac arrhythmias, prolonged somnolence and recovery, sneezing, coughing, bronchospasm, laryngospasm and shivering. Anaphylactic and anaphylactoid reactions to Bensulf (thiopental sodium) (Thiopental Sodium for Injection, USP) have been reported. Symptoms, e.g., urticaria, bronchospasm, vasodilation and edema should be managed by conventional means.
Rarely, immune hemolytic anemia with renal failure and radial nerve palsy have been reported.
DRUG ABUSE AND DEPENDENCE
WARNING: MAY BE HABIT FORMING.
Thiopental sodium is classified as a Schedule III controlled substance.
Diluents in Bensulf (thiopental sodium) ® Kits
Ready-To-Mix Syringes and VialsReactions which may occur because of the diluents, technique of preparation or mixing, or administration of reconstituted solutions of Bensulf (thiopental sodium) include febrile response or infection at the site of injection, venous thrombosis or phlebitis extending from the site of injection and extravasation.
If an adverse reaction does occur, discontinue the injection, evaluate the patient, institute appropriate therapeutic countermeasures and save the remainder of unused solution (or the used container or syringe) for examination if deemed necessary.
DRUG ABUSE AND DEPENDENCE
None known.
There are no preclinical data of relevance to the prescriber which are additional to that already included in other sections of the Summary of Product Characteristics.
1. Bensulf sodium is used for the induction of general anaesthesia and is also used as an adjunct to provide hypnosis during balanced anaesthesia with other anaesthetic agents, including analgesics and muscle relaxants.
2. Bensulf sodium is also used as an adjunct for control of convulsive disorders of various aetiology, including those caused by local anaesthetics.
3. Bensulf sodium has now been used to reduce the intracranial pressure in patients with increased intracranial pressure, if controlled ventilation is provided.
Bensulf
Bensulf (Thiopental Sodium for Injection, USP) is indicated (1) as the sole anesthetic agent for brief (15 minute) procedures, (2) for induction of anesthesia prior to administration of other anesthetic agents, (3) to supplement regional anesthesia, (4) to provide hypnosis during balanced anesthesia with other agents for analgesia or muscle relaxation, (5) for the control of convulsive states during or following inhalation anesthesia, local anesthesia, or other causes, (6) in neurosurgical patients with increased intracranial pressure, if adequate ventilation is provided, and (7) for narcoanalysis and narcosynthesis in psychiatric disorders.
Diluents in Bensulf (thiopental sodium) ® Kits
Ready-To-Mix Syringes and VialsThese products are indicated only for preparing Bensulf (Thiopental Sodium for Injection, USP) solutions for clinical use.
Pharmacotherapeutic Group: Anesthetics, General; Barbiturates, Plain
ATC code: N01AF03
Bensulf sodium is a short-acting substituted barbiturate that is more lipid soluble than other groups of barbiturates. The drug reversibly depresses the activity of all excitable tissues. The CNS is particularly sensitive and normally a general anaesthesia can be achieved with Bensulf sodium without significant effects on peripheral tissues.
Bensulf sodium acts through the CNS with particular activity in the mesencephalic reticular activating system. The barbiturates exert different effects on synaptic transmission, mostly those dependent on GABA. Autonomic ganglia of the peripheral nervous system are also depressed.
Following intravenous administration, unconsciousness occurs within 30 seconds and will be continued for 20 to 30 minutes after a single dose. Rapid uptake occurs to most vascular areas of the brain followed by redistribution into other tissues.
Bensulf sodium is strongly bound to plasma protein, which impairs excretion through the kidney. The metabolites are usually inactive and are then excreted. Bensulf sodium, therefore, whilst having a short duration of action, may have a long elimination phase.
Bensulf sodium causes respiratory depression and a reduction in cardiac output and may precipitate acute circulatory failure in patients with cardiovascular disease, particularly constrictive pericarditis.
When particular caution is required
Special care is needed in administering Bensulf sodium to patients with the following conditions:- hypovolaemia, severe haemorrhage, burns, cardiovascular disease, status asthmaticus, myasthenia gravis, adrenocortical insufficiency (even when controlled by cortisone), cachexia, raised intracranial pressure and raised blood urea.
Dose reduction required
Reduced doses are recommended in shock, dehydration, severe anaemia, hyperkalaemia, toxaemia, metabolic disorders e.g. thyrotoxicosis, myxoedema and diabetes.
Use in hepatic and renal disease
Bensulf sodium is metabolised primarily by the liver so doses should be reduced in patients with hepatic impairment. Barbiturate anaesthetics should be used with caution in severe renal disease. Reduced doses are also indicated in the elderly and in patients who have been premedicated with narcotic analgesics.
) and in underlying disease
Bensulf sodium has been shown to interact with sulphafurazole. Reduced initial doses may be required to achieve adequate anaesthesia, but repeat doses may also be necessary to maintain anaesthesia.
Patients taking long-term medications such as aspirin, oral anticoagulants, oestrogens, MAOIs and lithium may need to adjust the dose or stop therapy prior to elective surgery. Patients with diabetes or hypertension may need to adjust their therapy before anaesthesia.
Increased doses
Increased doses may be necessary in patients who have either a habituation or addiction to alcohol or drugs of abuse. Under these circumstances it is recommended that supplementary analgesic agents are used.
Extravasation
Extravasation causes local tissue necrosis and severe pain. This can be relieved by application of an ice pack and local injection of hydrocortisone. The 5% w/v solution is hypertonic and may cause pain on injection and thrombophlebitis.
Accidental intra-arterial injection
Accidental intra-arterial injection of Bensulf sodium causes severe arterial spasm and an intense burning pain around the injection site. In the case of accidental intra-arterial injection of Bensulf the needle should be left in-situ so that an injection of an antispasmodic, such as papaverine or prilocaine hydrochloride may be given. Anticoagulant therapy may also be started to reduce the risk of thrombosis.
Use in neurological patients with raised intracranial pressure
Bensulf has been associated with reports of severe or refractory hypokalaemia during infusion; severe rebound hyperkalaemia may occur after cessation of Bensulf infusion. The potential for rebound hyperkalaemia should be taken into account when stopping Bensulf therapy.
This medicinal product contains 53.5mg sodium per vial. To be taken into consideration by patients on a controlled sodium diet.
WARNINGSBensulf (thiopental sodium)
KEEP RESUSCITATIVE AND ENDOTRACHEAL INTUBATION EQUIPMENT AND OXYGEN READILY AVAILABLE. MAINTAIN PATENCY OF THE AIRWAY AT ALL TIMES.
This drug should be administered only by persons qualified in the use of intravenous anesthetics.
Avoid extravasation or intra-arterial injection.
WARNING: MAY BE HABIT FORMING.
Diluents in Bensulf (thiopental sodium) ® Kits
Ready-To-Mix Syringes and VialsIntravenous administration of Sterile Water for Injection, USP without a solute may result in hemolysis.
Use aseptic technique for preparing Bensulf (thiopental sodium) solutions when using Bensulf (thiopental sodium) Kits, Syringes or Vials and during withdrawal from reconstituted single or multiple-use containers.
Administer only clear reconstituted solutions.
Use within 24 hours after reconstitution. Discard unused portions.
PRECAUTIONSBensulf (thiopental sodium)
Observe aseptic precautions at all times in preparation and handling of Bensulf (Thiopental Sodium for Injection, USP) solutions.
If used in conditions involving relative contraindications, reduce dosage and administer slowly.
Care should be taken in administering the drug to patients with advanced cardiac disease, increased intracranial pressure, ophthalmoplegia plus, asthma, myasthenia gravis and endocrine insufficiency (pituitary, thyroid, adrenal, pancreas).
Drug Interactions
See DRUG INTERACTIONS section.
Nursing Mothers
Thiopental sodium readily crosses the placental barrier and small amounts may appear in the milk of nursing mothers following administration of large doses.
Pregnancy
Pregnancy Category C. Animal reproduction studies have not been conducted with Bensulf (thiopental sodium). It is also not known whether Bensulf (thiopental sodium) can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Bensulf (thiopental sodium) should be given to a pregnant woman only if clearly needed.
Diluents in Bensulf (thiopental sodium) ® Kits
Ready-To-Mix Syringes and VialsDo not use unless solution is clear and container is undamaged.
Inspect reconstituted (mixed) solutions of Bensulf (Thiopental Sodium for Injection, USP) for clarity and freedom from precipitation or discoloration prior to administration. Use reconstituted solution only if it is clear, free from precipitate and not discolored.
Use Transfer Label in each Bensulf (thiopental sodium) Kit and affix to container of reconstituted solution to show concentration and time of preparation.
Pregnancy
Pregnancy Category C. Animal reproduction studies have not been conducted with sterile water for injection or sodium chloride injection. It is also not known whether sterile water or sodium chloride injection containing additives can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Sterile water for injection or sodium chloride injection with additives should be given to a pregnant woman only if clearly needed.
Post-operative vertigo, disorientation and sedation may be prolonged and out-patients given Bensulf sodium should therefore be advised not to drive or use machinery, especially within the first 24 to 36 hours.
Intravenous injection.
Bensulf Sodium 500mg Injection is administered intravenously normally as a 2.5% w/v (500mg in 20ml) solution. On occasions it may be administered as a 5% w/v solution (500mg in 10ml).
The intravenous injection preparation should be used after reconstitution of the sterile powder with Water for Injections, usually to produce a 2.5% w/v solution and this should be discarded after seven hours.
Use in anaesthesia
Normal dosage for the induction of anaesthesia is 100mg to 150mg injected over 10 to 15 seconds. If necessary a repeat dose of 100mg to 150mg may be given after one minute. No fixed dosage recommendations for the intravenous injection can be given, since the dosage will need to be carefully adjusted according to the patient's response. Factors such as age, sex, and weight of the patient should be taken into consideration. Bensulf sodium reaches effective concentrations in the brain within 30 seconds and anaesthesia is normally produced within one minute of an intravenous dose.
Adult
100mg to 150mg intravenously over 10 to 15 seconds, normally as a 2.5% w/v solution.
A repeat dose of 100mg to 150mg may be given after one minute.
The intravenous injection should be given slowly and the amounts given titrated against the patient's response to minimise the risk of respiratory depression or the possibility of overdosage. The average dose for an adult of 70kg is roughly 200mg to 300mg (8mls to 12mls of a 2.5% w/v solution) with a maximum of 500mg.
Children
2 to 7mg/kg bodyweight, intravenously over 10 to 15 seconds, normally as a 2.5% w/v solution. A repeat dose of 2 to 7mg/kg may be given after one minute. The dose is 2 to 7mg/kg based on the patient's response. The dose for children should not exceed 7mg/kg.
Elderly
Smaller adult doses are advisable.
Use in convulsive states
75mg to 125mg (3mls to 5mls of a 2.5% w/v solution) should be given as soon as possible after the convulsion begins. Further doses may be required to control convulsions following the use of a local anaesthetic. Other regimens, such as the use of intravenous or rectal diazepam, may be used to control convulsive states.
Use in neurological patients with raised intracranial pressure
Intermittent bolus injections of 1.5 to 3mg/kg of bodyweight may be given to reduce elevations of intracranial pressure if controlled ventilation is provided.
Bensulf (thiopental sodium)
Bensulf (thiopental sodium) is administered by the intravenous route only. Individual response to the drug is so varied that there can be no fixed dosage. The drug should be titrated against patient requirements as governed by age, sex and body weight. Younger patients require relatively larger doses than middle-aged and elderly persons; the latter metabolize the drug more slowly. Pre-puberty requirements are the same for both sexes, but adult females require less than adult males. Dose is usually proportional to body weight and obese patients require a larger dose than relatively lean persons of the same weight.
Premedication
Premedication usually consists of atropine or scopolamine to suppress vagal reflexes and inhibit secretions. In addition, a barbiturate or an opiate is often given. Sodium pentobarbital injection (Nembutal®) is suggested because it provides a preliminary indication of how the patient will react to barbiturate anesthesia. Ideally, the peak effect of these medications should be reached shortly before the time of induction.
Test Dose
It is advisable to inject a small "test" dose of 25 to 75 mg (1 to 3 mL of a 2.5% solution) of Bensulf (Thiopental Sodium for Injection, USP) to assess tolerance or unusual sensitivity to Bensulf (thiopental sodium) , and pausing to observe patient reaction for at least 60 seconds. If unexpectedly deep anesthesia develops or if respiratory depression occurs, consider these possibilities: (1) the patient may be unusually sensitive to Bensulf (thiopental sodium) , (2) the solution may be more concentrated than had been assumed, or (3) the patient may have received too much premedication.
Use in Anesthesia
Moderately slow induction can usually be accomplished in the "average" adult by injection of 50 to 75 mg (2 to 3 mL of a 2.5% solution) at intervals of 20 to 40 seconds, depending on the reaction of the patient. Once anesthesia is established, additional injections of 25 to 50 mg can be given whenever the patient moves.
Slow injection is recommended to minimize respiratory depression and the possibility of overdosage. The smallest dose consistent with attaining the surgical objective is the desired goal. Momentary apnea following each injection is typical, and progressive decrease in the amplitude of respiration appears with increasing dosage. Pulse remains normal or increases slightly and returns to normal. Blood pressure usually falls slightly but returns toward normal. Muscles usually relax about 30 seconds after unconsciousness is attained, but this may be masked if a skeletal muscle relaxant is used. The tone of jaw muscles is a fairly reliable index. The pupils may dilate but later contract; sensitivity to light is not usually lost until a level of anesthesia deep enough to permit surgery is attained. Nystagmus and divergent strabismus are characteristic during early stages, but at the level of surgical anesthesia, the eyes are central and fixed. Corneal and conjunctival reflexes disappear during surgical anesthesia.
When Bensulf (Thiopental Sodium for Injection, USP) is used for induction in balanced anesthesia with a skeletal muscle relaxant and an inhalation agent, the total dose of Bensulf (thiopental sodium) can be estimated and then injected in two to four fractional doses. With this technique, brief periods of apnea may occur which may require assisted or controlled pulmonary ventilation. As an initial dose, 210 to 280 mg (3 to 4 mg/kg) of Bensulf (thiopental sodium) is usually required for rapid induction in the average adult (70 kg).
When Bensulf (Thiopental Sodium for Injection, USP) is used as the sole anesthetic agent, the desired level of anesthesia can be maintained by injection of small repeated doses as needed or by using a continuous intravenous drip in a 0.2% or 0.4% concentration. (Sterile water should not be used as the diluent in these concentrations, since hemolysis will occur.) With continuous drip, the depth of anesthesia is controlled by adjusting the rate of infusion.
Use in Convulsive States
For the control of convulsive states following anesthesia (inhalation or local) or other causes, 75 to 125 mg (3 to 5 mL of a 2.5% solution) should be given as soon as possible after the convulsion begins. Convulsions following the use of a local anesthetic may require 125 to 250 mg of Bensulf (thiopental sodium) given over a ten minute period. If the convulsion is caused by a local anesthetic, the required dose of Bensulf (thiopental sodium) will depend upon the amount of local anesthetic given and its convulsant properties.
Use in Neurosurgical Patients with Increased Intracranial Pressure
In neurosurgical patients, intermittent bolus injections of 1.5 to 3.5 mg/kg of body weight may be given to reduce intraoperative elevations of intracranial pressure, if adequate ventilation is provided.
Use in Psychiatric Disorders
For narcoanalysis and narcosynthesis in psychiatric disorders, premedication with an anticholinergic agent may precede administration of Bensulf. After a test dose, Bensulf (Thiopental Sodium for Injection, USP) is injected at a slow rate of 100 mg/mm (4 mL/min of a 2.5% solution) with the patient counting backwards from 100. Shortly after counting becomes confused but before actual sleep is produced, the injection is discontinued. Allow the patient to return to a semidrowsy state where conversation is coherent. Alternatively, Bensulf (thiopental sodium) may be administered by rapid I.V. drip using a 0.2% concentration in 5% dextrose and water. At this concentration, the rate of administration should not exceed 50 mL/min.
MANAGEMENT OF SOME COMPLICATIONS
Respiratory depression (hypoventilation, apnea), which may result from either unusual responsiveness to Bensulf (thiopental sodium) or overdosage, is managed as stated above. Bensulf (thiopental sodium) should be considered to have the same potential for producing respiratory depression as an inhalation agent, and patency of the airway must be protected at all times.
Laryngospasm may occur with light Bensulf (thiopental sodium) narcosis at intubation, or in the absence of intubation if foreign matter or secretions in the respiratory tract create irritation. Laryngeal and bronchial vagal reflexes can be suppressed, and secretions minimized by giving atropine or scopolamine premedication and a barbiturate or opiate. Use of a skeletal muscle relaxant or positive pressure oxygen will usually relieve laryngospasm. Tracheostomy may be indicated in difficult cases.
Myocardial depression, proportional to the amount of drug in direct contact with the heart, can occur and may cause hypotension, particularly in patients with an unhealthy myocardium. Arrhythmias may appear if PCO2 is elevated, but they are uncommon with adequate ventilation. Management of myocardial depression is the same as for overdosage. Bensulf (Thiopental Sodium for Injection, USP) does not sensitize the heart to epinephrine or other sympathomimetic amines.
Extra vascular infiltration should be avoided. Care should be taken to insure that the needle is within the lumen of the vein before injection of Bensulf (thiopental sodium). Extravascular injection may cause chemical irritation of the tissues varying from slight tenderness to venospasm, extensive necrosis and sloughing. This is due primarily to the high alkaline pH (10 to 11) of clinical concentrations of the drug. If extravasation occurs, the local irritant effects can be reduced by injection of 1% procaine locally to relieve pain and enhance vasodilatation. Local application of heat also may help to increase local circulation and removal of the infiltrate.
Intra-arterial injection can occur inadvertently, especially if an aberrant superficial artery is present at the medial aspect of the antecubital fossa. The area selected for intravenous injection of the drug should be palpated for detection of an underlying pulsating vessel. Accidental intra-arterial injection can cause arteriospasm and severe pain along the course of the artery with blanching of the arm and fingers. Appropriate corrective measures should be instituted promptly to avoid possible development of gangrene. Any patient complaint of pain warrants stopping the injection. Methods suggested for dealing with this complication vary with the severity of symptoms. The following have been suggested:
1. Dilute the injected Bensulf (Thiopental Sodium for Injection, USP) by removing the tourniquet and any restrictive garments.
2. Leave the needle in place, if possible.
3. Inject the artery with a dilute solution of papaverine, 40 to 80 mg, or 10 mL of 1% procaine, to inhibit smooth muscle spasm.
4. If necessary, perform sympathetic block of the brachial plexus and/or stellate ganglion to relieve pain and assist in opening collateral circulation. Papaverine can be injected into the subclavian artery, if desired.
5. Unless otherwise contraindicated, institute immediate heparinization to prevent thrombus formation.
6. Consider local infiltration of an alpha-adrenergic blocking agent such as phentolamine into the vasospastic area.
7. Provide additional symptomatic treatment as required.
Shivering after Bensulf (thiopental sodium) anesthesia, manifested by twitching face muscles and occasional progression to tremors of the arms, head, shoulder and body, is a thermal reaction due to increased sensitivity to cold. Shivering appears if the room environment is cold and if a large ventilatory heat loss has been sustained with balanced inhalation anesthesia employing nitrous oxide. Treatment consists of warming the patient with blankets, maintaining room temperature near 22°C (72°F), and administration of chlorpromazine or methylphenidate.
PREPARATION OF SOLUTIONS
Bensulf
Bensulf (Thiopental Sodium for Injection, USP) is supplied as a yellowish, hygroscopic powder in a variety of different containers. Solutions should be prepared aseptically with one of the three following diluents: Sterile Water for Injection, USP, 0.9% Sodium Chloride Injection, USP or 5% Dextrose Injection, USP. Clinical concentrations used for intermittent intravenous administration vary between 2.0% and 5.0%. A 2.0% or 2.5% solution is most commonly used. A 3.4% concentration in sterile water for injection is isotonic; concentrations less than 2.0% in this diluent are not used because they cause hemolysis. For continuous intravenous drip administration, concentrations of 0.2% or 0.4% are used. Solutions may be prepared by adding Bensulf (thiopental sodium) to 5% Dextrose Injection, USP, 0.9% Sodium Chloride Injection, USP or Normosol®-R pH 7.4.
Since Bensulf (thiopental sodium) contains no added bacteriostatic agent, extreme care in preparation and handling should be exercised at all times to prevent the introduction of microbial contaminants. Solutions should be freshly prepared and used promptly; when reconstituted for administration to several patients, unused portions should be discarded after 24 hours. Sterilization by heating should not be attempted.
WARNING: The 2.5 g and larger sizes contain adequate medication for several patients.
COMPATIBILITY
Bensulf
Any solution of Bensulf (Thiopental Sodium for Injection, USP) with a visible precipitate should not be administered. The stability of Bensulf (thiopental sodium) solutions depends upon several factors, including the diluent, temperature of storage and the amount of carbon dioxide from room air that gains access to the solution. Any factor or condition which tends to lower pH (increase acidity) of Bensulf (thiopental sodium) solutions will increase the likelihood of precipitation of thiopental acid. Such factors include the use of diluents which are too acidic and the absorption of carbon dioxide which can combine with water to form carbonic acid.
Solutions of succinylcholine, tubocurarine or other drugs which have an acid pH should not be mixed with Bensulf (thiopental sodium) solutions. The most stable solutions are those reconstituted in water or isotonic saline, kept under refrigeration and tightly stoppered. The presence or absence of a visible precipitate offers a practical guide to the physical compatibility of prepared solutions of Bensulf (thiopental sodium).
CALCULATIONS FOR VARIOUS CONCENTRATIONS
| Concentration | mounts to Use | ||
| Desired | Bensulf | Diluent | |
| Percent | mg/ml | g | ml |
| 0.2 | 2 | 1 | 500 |
| 0.4 | 4 | 1 | 250 |
| 2 | 500 | ||
| 2.0 | 20 | 5 | 250 |
| 10 | 500 | ||
| 2.5 | 25 | 1 | 40 |
| 5 | 200 | ||
| 5 | 50 | 1 | 20 |
| 5 | 100 | ||
Reconstituted solutions of Bensulf (Thiopental Sodium for Injection, USP) should be inspected visually for particulate matter and discoloration, whenever solution and container permit.
Diluents in Bensulf (thiopental sodium) ® Kits
Ready-To-Mix Syringes and VialsBensulf (thiopental sodium) solutions should be administered only by intravenous injection and by individuals experienced in the conduct of intravenous anesthesia.
The volume and choice of diluent for preparing Bensulf (Thiopental Sodium for Injection, USP) solutions for clinical use depends on the concentration and vehicle desired. Bensulf (thiopental sodium) Kits provide only Sterile Water for Injection as the diluent for individual or multi-patient use; Bensulf (thiopental sodium) Ready-to-Mix Syringes provide only 0.9% Sodium Chloride Injection, USP as the diluent for individual patient use; vials provide only Sterile Water for Injection, USP as the diluent for individual patient use.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. See PRECAUTIONS.
Solutions for administration are prepared by adding Water for Injection and shaking to dissolve the contents of the vial. The following guide may be followed:
|
500mg vial | 2.5% Solution 25mg per ml Add 20ml | 5% Solution 50mg per ml Add 10ml |
Solutions must be used within 7 hours or preparation, or discarded. Do not use if the solution is discoloured.
