Amifostine

Overdose

In clinical trials, the maximum single dose of Amifostine (amifostine) was 1300 mg/m2. No information is available on single doses higher than this in adults. In the setting of a clinical trial, pediatric patients have received single Amifostine (amifostine) doses of up to 2700 mg/m2. At the higher doses, anxiety and reversible urinary retention occurred.

Administration of Amifostine (amifostine) at 2 and 4 hours after the initial dose has not led to increased nausea and vomiting or hypotension. The most likely symptom of overdosage is hypotension, which should be managed by infusion of normal saline and other supportive measures, as clinically indicated.

Contraindications

Amifostine (amifostine) is contraindicated in patients with known hypersensitivity to aminothiol compounds.

Pharmaceutical form

Undesirable effects

In the randomized study of patients with ovarian cancer given Amifostine (amifostine) at a dose of 910 mg/m2 prior to chemotherapy, transient hypotension was observed in 62% of patients treated. The mean time of onset was 14 minutes into the 15-minute period of Amifostine (amifostine) infusion, and the mean duration was 6 minutes. In some cases, the infusion had to be prematurely terminated due to a more pronounced drop in systolic blood pressure. In general, the blood pressure returned to normal within 5-15 minutes. Fewer than 3% of patients discontinued Amifostine (amifostine) due to blood pressure reductions. In the randomized study of patients with head and neck cancer given Amifostine (amifostine) at a dose of 200 mg/m2 prior to radiotherapy, hypotension was observed in 15% of patients treated. (see TABLE 6)

TABLE 6: Incidence of Common Adverse Events in Patients Receiving Amifostine (amifostine)

In the randomized study of patients with head and neck cancer, 17% (26/150) discontinued Amifostine (amifostine) due to adverse events. All but one of these patients continued to receive radiation treatment until completion.

Hypotension that requires interruption of the Amifostine (amifostine) infusion should be treated with fluid infusion and postural management of the patient (supine or Trendelenburg position). If the blood pressure returns to normal within 5 minutes and the patient is asymptomatic, the infusion may be restarted, so that the full dose of Amifostine (amifostine) can be administered. Short term, reversible loss of consciousness has been reported rarely.

Nausea and/or vomiting occur frequently after Amifostine (amifostine) infusion and may be severe. In the ovarian cancer randomized study, the incidence of severe nausea/vomiting on day 1 of cyclophosphamide-cisplatin chemotherapy was 10% in patients who did not receive Amifostine (amifostine) , and 19% in patients who did receive Amifostine (amifostine). In the randomized study of patients with head and neck cancer, the incidence of severe nausea/vomiting was 8% in patients who received Amifostine (amifostine) and 1% in patients who did not receive Amifostine (amifostine).

Decrease in serum calcium concentrations is a known pharmacological effect of Amifostine (amifostine). At the recommended doses, clinically significant hypocalcemia was reported in 1% of patients in the randomized head and neck cancer study (see WARNINGS), and not reported in the ovarian cancer study.

Other effects, which have been described during, or following Amifostine (amifostine) infusion are flushing/feeling of warmth, chills/feeling of coldness, malaise, fever, rash, dizziness, somnolence, hiccups and sneezing. These effects have not generally precluded the completion of therapy.

Allergic reactions characterized by one or more of the following manifestations have been observed during or after Amifostine (amifostine) administration: hypotension, fever, chills/rigors, dyspnea, hypoxia, chest tightness, cutaneous eruptions, pruritus, urticaria and laryngeal edema. Cutaneous eruptions have been commonly reported during clinical trials and were generally non-serious. Serious, sometimes fatal skin reactions including erythema multiforme, and in rare cases, exfoliative dermatitis, Stevens-Johnson syndrome and toxic epidermal necrolysis have also occurred. The reported incidence of serious skin reactions associated with Amifostine (amifostine) is higher in patients receiving Amifostine (amifostine) as a radioprotectant than in patients receiving Amifostine (amifostine) as a chemoprotectant. Rare anaphylactoid reactions and cardiac arrest have also been reported.

Hypotension, usually brief systolic and diastolic, has been associated with one or more of the following adverse events: apnea, dyspnea, hypoxia, tachycardia, bradycardia, extrasystoles, chest pain, myocardial ischemia and convulsion. Rare cases of renal failure, myocardial infarction, respiratory and cardiac arrest have been observed during or after hypotension. (See WARNINGS and PRECAUTIONS)

Rare cases of arrhythmias such as atrial fibrillation/flutter and supraventricular tachycardia have been reported. These are sometimes associated with hypotension or allergic reactions.

Transient hypertension and exacerbations of preexisting hypertension have been observed rarely after Amifostine (amifostine) administration.

Seizures and syncope have been reported rarely. (See WARNINGS and PRECAUTIONS)

Therapeutic indications

Amifostine (amifostine) is indicated to reduce the cumulative renal toxicity associated with repeated administration of cisplatin in patients with advanced ovarian cancer.

Amifostine (amifostine) is indicated to reduce the incidence of moderate to severe xerostomia in patients undergoing post-operative radiation treatment for head and neck cancer, where the radiation port includes a substantial portion of the parotid glands (see Clinical Studies).

For the approved indications, the clinical data do not suggest that the effectiveness of cisplatin based chemotherapy regimens or radiation therapy is altered by Amifostine (amifostine). There are at present only limited data on the effects of Amifostine (amifostine) on the efficacy of chemotherapy or radiotherapy in other settings. Amifostine (amifostine) should not be administered to patients in other settings where chemotherapy can produce a significant survival benefit or cure, or in patients receiving definitive radiotherapy, except in the context of a clinical study (see WARNINGS).

Name of the medicinal product

Qualitative and quantitative composition

Special warnings and precautions for use

Limited data are currently available regarding the preservation of antitumor efficacy when Amifostine (amifostine) is administered prior to cisplatin therapy in settings other than advanced ovarian cancer. Although some animal data suggest interference is possible, in most tumor models the antitumor effects of chemotherapy are not altered by amifostine. Amifostine (amifostine) should not be used in patients receiving chemotherapy for other malignancies in which chemotherapy can produce a significant survival benefit or cure (e.g., certain malignancies of germ cell origin), except in the context of a clinical study.

Amifostine (amifostine) should not be administered in patients receiving definitive radiotherapy, except in the context of a clinical trial, since there are at present insufficient data to exclude a tumor-protective effect in this setting. Amifostine (amifostine) was studied only with standard fractionated radiotherapy and only when ≥ 75% of both parotid glands were exposed to radiation. The effects of Amifostine (amifostine) on the incidence of xerostomia and on toxicity in the setting of combined chemotherapy and radiotherapy and in the setting of accelerated and hyperfractionated therapy have not been systematically studied.

Patients who are hypotensive or in a state of dehydration should not receive Amifostine (amifostine). Patients receiving Amifostine (amifostine) at doses recommended for chemotherapy should have antihypertensive therapy interrupted 24 hours preceding administration of Amifostine (amifostine). Patients receiving Amifostine (amifostine) at doses recommended for chemotherapy who are taking antihypertensive therapy that cannot be stopped for 24 hours preceding Amifostine (amifostine) treatment, should not receive Amifostine (amifostine).

Prior to Amifostine (amifostine) infusion patients should be adequately hydrated. During Amifostine (amifostine) infusion patients should be kept in a supine position. Blood pressure should be monitored every 5 minutes during the infusion, and thereafter as clinically indicated. It is important that the duration of the 910 mg/m2 infusion not exceed 15 minutes, as administration of Amifostine (amifostine) as a longer infusion is associated with a higher incidence of side effects. For infusion durations less than 5 minutes, blood pressure should be monitored at least before and immediately after the infusion, and thereafter as clinically indicated. If hypotension occurs, patients should be placed in the Trendelenburg position and be given an infusion of normal saline using a separate i.v. line. During and after Amifostine (amifostine) infusion, care should be taken to monitor the blood pressure of patients whose antihypertensive medication has been interrupted since hypertension may be exacerbated by discontinuation of antihypertensive medication and other causes such as i.v. hydration.

Guidelines for interrupting and restarting Amifostine (amifostine) infusion if a decrease in systolic blood pressure should occur are provided in the DOSAGE AND ADMINISTRATION section. Hypotension may occur during or shortly after Amifostine (amifostine) infusion, despite adequate hydration and positioning of the patient (see ADVERSE REACTIONS and PRECAUTIONS). Hypotension has been reported to be associated with dyspnea, apnea, hypoxia, and in rare cases seizures, unconsciousness, respiratory arrest and renal failure.

Serious cutaneous reactions have been associated rarely with Amifostine (amifostine) administration. Serious cutaneous reactions have included erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, toxoderma and exfoliative dermatitis. These reactions have been reported more frequently when Amifostine is used as a radioprotectant (see ADVERSE REACTIONS). Some of these reactions have been fatal or have required hospitalization and/or discontinuance of therapy Patients should be carefully. monitored prior to, during and after Amifostine (amifostine) administration. Serious cutaneous reactions may develop weeks after initiation of Amifostine (amifostine) administration (see PRECAUTIONS).

Allergic manifestations including anaphylaxis and severe cutaneous reactions have been associated rarely with Amifostine (amifostine) administration.

Antiemetic medication should be administered prior to and in conjunction with Amifostine (see DOSAGE AND ADMINISTRATlON). When Amifostine (amifostine) is administered with highly emetogenic chemotherapy, the fluid balance of the patient should be carefully monitored.

Serum calcium levels should be monitored in patients at risk of hypocalcemia, such as those with nephrotic syndrome or patients receiving multiple doses of Amifostine (see ADVERSE REACTIONS). If necessary, calcium supplements can be administered.

Patients should be adequately hydrated prior to the Amifostine (amifostine) infusion and blood pressure should be monitored (see DOSAGE AND ADMINISTRATION).

The safety of Amifostine (amifostine) administration has not been established in elderly patients, or in patients with preexisting cardiovascular or cerebrovascular conditions such as ischemic heart disease, arrhythmias, congestive heart failure, or history of stroke or transient ischemic attacks. Amifostine (amifostine) should be used with particular care in these and other patients in whom the common Amifostine (amifostine) adverse effects of nausea/vomiting and hypotension may be more likely to have serious consequences.

Prior to chemotherapy, Amifostine (amifostine) should be administered as a 15-minute infusion (see DOSAGE AND ADMINISTRATION). Blood pressure should be monitored every 5 minutes during the infusion, and thereafter as clinically indicated.

Prior to radiation therapy, Amifostine (amifostine) should be administered as a 3-minute infusion (see DOSAGE AND ADMINISTRATION). Blood pressure should be monitored at least before and immediately after the infusion, and thereafter as clinically indicated.

Based on cutaneous evaluation, cutaneous reactions may require permanent discontinuation of Amifostine (amifostine) or urgent dermatologic consultation and biopsy (see below).

Cutaneous evaluation of the patient prior to each Amifostine (amifostine) administration should be performed with particular attention paid to the development of the following:

-Any rash involving the lips or involving mucosa not known to be due to another etiology (e.g., radiation mucositis, herpes simplex, etc.)

-Erythematous, edematous, or bullous lesions on the palms of the hands or soles of the feet and/or other cutaneous reactions on the trunk (front, back, abdomen)

-Cutaneous reactions with associated fever or other constitutional symptoms

Cutaneous reactions must be clearly differentiated from radiation-induced dermatitis and from cutaneous reactions related to an alternate etiology. Amifostine (amifostine) should also be permanently discontinued for serious or severe cutaneous reactions (see WARNINGS and ADVERSE REACTIONS) or for cutaneous reactions associated with fever or other constitutional symptoms not known to be due to another etiology. Amifostine (amifostine) should be withheld and dermatologic consultation and biopsy considered for cutaneous reactions or mucosal lesions of unknown etiology appearing outside of the injection site or radiation port and for erythematous, edematous or bullous lesions on the palms of the hand or soles of the feet. Reinitiation of Amifostine (amifostine) should be at the physician's discretion based on medical judgment and appropriate dermatologic evaluation.

In case of severe acute allergic reactions Amifostine (amifostine) should be immediately and permanently discontinued. Epinephrine and other appropriate measures should be available for treatment of serious allergic events such as anaphylaxis.

No long term animal studies have been performed to evaluate the carcinogenic potential of Amifostine (amifostine). Amifostine (amifostine) was negative in the Ames test and in the mouse micronucleus test. The free thiol metabolite was positive in the Ames test with S9 microsomal fraction in the TA1535 Salmonella typhimuriumstrain and at the TK locus in the mouse L5178Y cell assay. The metabolite was negative in the mouse micronucleus test and negative for clastogenicity in human lymphocytes.

Pregnancy Category C. Amifostine (amifostine) has been shown to be embryotoxic in rabbits at doses of 50 mg/kg, approximately sixty percent of the recommended dose in humans on a body surface area basis. There are no adequate and well-controlled studies in pregnant women. Amifostine (amifostine) should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

No information is available on the excretion of Amifostine (amifostine) or its metabolites into human milk. Because many drugs are excreted in human milk and because of the potential for adverse reactions in nursing infants, it is recommended that breast feeding be discontinued if the mother is treated with Amifostine (amifostine).

The safety and effectiveness in pediatric patients have not been established.

The clinical studies did not include sufficient number of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between elderly and younger patients. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function and of concomitant disease or other drug therapy in elderly patients.

Dosage (Posology) and method of administration

The recommended starting dose of Amifostine (amifostine) is 910 mg/m2 administered once daily as a 15-minute i.v. infusion, starting 30 minutes prior to chemotherapy.

The 15-minute infusion is better tolerated than more extended infusions. Further reductions in infusion times for chemotherapy regimens have not been systematically investigated.

Patients should be adequately hydrated prior to Amifostine (amifostine) infusion and kept in a supine position during the infusion. Blood pressure should be monitored every 5 minutes during the infusion, and thereafter as clinically indicated.

The infusion of Amifostine (amifostine) should be interrupted if the systolic blood pressure decreases significantly from the baseline value as listed in the guideline below:

Guideline for Interrupting Amifostine (amifostine) Infusion Due to Decrease in Systolic Blood Pressure

If the blood pressure returns to normal within 5 minutes and the patient is asymptomatic, the infusion may be restarted so that the full dose of Amifostine (amifostine) may be administered. If the full dose of Amifostine (amifostine) cannot be administered, the dose of Amifostine (amifostine) for subsequent chemotherapy cycles should be 740 mg/m2.

It is recommended that antiemetic medication, including dexamethasone 20 mg i.v. and a serotonin 5HT3 receptor antagonist, be administered prior to and in conjunction with Amifostine (amifostine). Additional antiemetics may be required based on the chemotherapy drugs administered.

The recommended dose of Amifostine (amifostine) is 200 mg/m2 administered once daily as a 3-minute i.v. infusion, starting 15-30 minutes prior to standard fraction radiation therapy (1.8-2.0 Gy).

Patients should be adequately hydrated prior to Amifostine (amifostine) infusion. Blood pressure should be monitored at least before and immediately after the infusion, and thereafter as clinically indicated.

It is recommended that antiemetic medication be administered prior to and in conjunction with Amifostine (amifostine). Oral 5HT3 receptor antagonists, alone or in combination with other antiemetics, have been used effectively in the radiotherapy setting.

Amifostine (amifostine) for Injection is supplied as a sterile lyophilized powder requiring reconstitution for intravenous infusion. Each single-use vial contains 500 mg of amifostine on the anhydrous basis.

Prior to intravenous injection, Amifostine (amifostine) is reconstituted with 9.7 mL of sterile 0.9% Sodium Chloride Injection, USP. The reconstituted solution (500 mg amifostine/10 mL) is chemically stable for up to 5 hours at room temperature (approximately 25°C) or up to 24 hours under refrigeration (2°C to 8°C).

Amifostine (amifostine) prepared in polyvinylchloride (PVC) bags at concentrations ranging from 5 mg/mL to 40 mg/mL is chemically stable for up to 5 hours when stored at room temperature (approximately 25°C) or up to 24 hours when stored under refrigeration (2°C to 8°C).

CAUTION: Parenteral products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. Do not use if cloudiness or precipitate is observed.

The compatibility of Amifostine (amifostine) with solutions other than 0.9% Sodium Chloride for Injection, or Sodium Chloride solutions with other additives, has not been examined. The use of other solutions is not recommended.