Amifos

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

Amifos (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 Amifos (amifostine). There are at present only limited data on the effects of Amifos (amifostine) on the efficacy of chemotherapy or radiotherapy in other settings. Amifos (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).

For Reduction of Cumulative Renal Toxicity with Chemotherapy:

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

Guideline for Interrupting Amifos (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 Amifos (amifostine) may be administered. If the full dose of Amifos (amifostine) cannot be administered, the dose of Amifos (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 Amifos (amifostine). Additional antiemetics may be required based on the chemotherapy drugs administered.

For Reduction of Moderate to Severe Xerostomia from Radiation of the Head and Neck:

The recommended dose of Amifos (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 Amifos (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 Amifos (amifostine). Oral 5HT3 receptor antagonists, alone or in combination with other antiemetics, have been used effectively in the radiotherapy setting.

Reconstitution

Amifos (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, Amifos (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).

Amifos (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.

Incompatibilities

The compatibility of Amifos (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.

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

WARNINGS

1. Effectiveness of the Cytotoxic Regimen

Limited data are currently available regarding the preservation of antitumor efficacy when Amifos (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. Amifos (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.

2. Effectiveness of Radiotherapy

Amifos (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. Amifos (amifostine) was studied only with standard fractionated radiotherapy and only when ≥ 75% of both parotid glands were exposed to radiation. The effects of Amifos (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.

3. Hypotension

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

Prior to Amifos (amifostine) infusion patients should be adequately hydrated. During Amifos (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 Amifos (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 Amifos (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 Amifos (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 Amifos (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.

4. Cutaneous Reactions

Serious cutaneous reactions have been associated rarely with Amifos (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 Amifos 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 Amifos (amifostine) administration. Serious cutaneous reactions may develop weeks after initiation of Amifos (amifostine) administration (see PRECAUTIONS).

5. Hypersensitivity

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

6. Nausea and Vomiting

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

7. Hypocalcemia

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

PRECAUTIONS

General

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

The safety of Amifos (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. Amifos (amifostine) should be used with particular care in these and other patients in whom the common Amifos (amifostine) adverse effects of nausea/vomiting and hypotension may be more likely to have serious consequences.

Prior to chemotherapy, Amifos (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, Amifos (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.

Cutaneous Reactions

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

Cutaneous evaluation of the patient prior to each Amifos (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. Amifos (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. Amifos (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 Amifos (amifostine) should be at the physician's discretion based on medical judgment and appropriate dermatologic evaluation.

Allergic Reactions

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

Carcinogenesis, Mutagenesis, Impairment of Fertility

No long term animal studies have been performed to evaluate the carcinogenic potential of Amifos (amifostine). Amifos (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

Pregnancy Category C. Amifos (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. Amifos (amifostine) should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

No information is available on the excretion of Amifos (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 Amifos (amifostine).

Pediatric Use

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

Geriatric Use

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.

Controlled Trials

In the randomized study of patients with ovarian cancer given Amifos (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 Amifos (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 Amifos (amifostine) due to blood pressure reductions. In the randomized study of patients with head and neck cancer given Amifos (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 Amifos (amifostine)

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

Hypotension that requires interruption of the Amifos (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 Amifos (amifostine) can be administered. Short term, reversible loss of consciousness has been reported rarely.

Nausea and/or vomiting occur frequently after Amifos (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 Amifos (amifostine) , and 19% in patients who did receive Amifos (amifostine). In the randomized study of patients with head and neck cancer, the incidence of severe nausea/vomiting was 8% in patients who received Amifos (amifostine) and 1% in patients who did not receive Amifos (amifostine).

Decrease in serum calcium concentrations is a known pharmacological effect of Amifos (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 Amifos (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.

Clinical Trials and Pharmacovigilance Reports

Allergic reactions characterized by one or more of the following manifestations have been observed during or after Amifos (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 Amifos (amifostine) is higher in patients receiving Amifos (amifostine) as a radioprotectant than in patients receiving Amifos (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 Amifos (amifostine) administration.

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

In clinical trials, the maximum single dose of Amifos (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 Amifos (amifostine) doses of up to 2700 mg/m². At the higher doses, anxiety and reversible urinary retention occurred.

Administration of Amifos (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.