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amifostine injection, powder, lyophilized, for solution
ETHYOL (amifostine) is an organic thiophosphate cytoprotective agent known chemically as 2-[(3-aminopropyl)amino]ethanethiol dihydrogen phosphate (ester) and has the following structural formula:
Amifostine is a white crystalline powder which is freely soluble in water. Its empirical formula is C5H15N2O3PS and it has a molecular weight of 214.22.
ETHYOL is the trihydrate form of amifostine and is supplied as a sterile lyophilized powder requiring reconstitution for intravenous infusion. Each single-use 10 mL vial contains 500 mg of amifostine on the anhydrous basis.
ETHYOL is a prodrug that is dephosphorylated by alkaline phosphatase in tissues to a pharmacologically active free thiol metabolite. This metabolite is believed to be responsible for the reduction of the cumulative renal toxicity of cisplatin and for the reduction of the toxic effects of radiation on normal oral tissues. The ability of ETHYOL to differentially protect normal tissues is attributed to the higher capillary alkaline phosphatase activity, higher pH and better vascularity of normal tissues relative to tumor tissue, which results in a more rapid generation of the active thiol metabolite as well as a higher rate constant for uptake into cells. The higher concentration of the thiol metabolite in normal tissues is available to bind to, and thereby detoxify, reactive metabolites of cisplatin. This thiol metabolite can also scavenge reactive oxygen species generated by exposure to either cisplatin or radiation.
Clinical pharmacokinetic studies show that ETHYOL is rapidly cleared from the plasma with a distribution half-life of < 1 minute and an elimination half-life of approximately 8 minutes. Less than 10% of ETHYOL remains in the plasma 6 minutes after drug administration. ETHYOL is rapidly metabolized to an active free thiol metabolite. A disulfide metabolite is produced subsequently and is less active than the free thiol. After a 10-second bolus dose of 150 mg/m2 of ETHYOL, renal excretion of the parent drug and its two metabolites was low during the hour following drug administration, averaging 0.69%, 2.64% and 2.22% of the administered dose for the parent, thiol and disulfide, respectively. Measurable levels of the free thiol metabolite have been found in bone marrow cells 5-8 minutes after intravenous infusion of ETHYOL. Pretreatment with dexamethasone or metoclopramide has no effect on ETHYOL pharmacokinetics.
In the randomized ovarian cancer study, ETHYOL had no detectable effect on the antitumor efficacy of cisplatin-cyclophosphamide chemotherapy. Objective response rates (including pathologically confirmed complete remission rates), time to progression, and survival duration were all similar in the ETHYOL and control study groups. The table below summarizes the principal efficacy findings of the randomized ovarian cancer study.
Radiotherapy for Head and Neck Cancer. A randomized controlled trial of standard fractionated radiation (1.8 Gy - 2.0 Gy/day for 5 days/week for 5-7 weeks) with or without ETHYOL, administered at 200 mg/m2 as a 3 minute i.v. infusion 15-30 minutes prior to each fraction of radiation, was conducted in 315 patients with head and neck cancer. Patients were required to have at least 75% of both parotid glands in the radiation field. The incidence of Grade 2 or higher acute (90 days or less from start of radiation) and late xerostomia (9-12 months following radiation) as assessed by RTOG Acute and Late Morbidity Scoring Criteria, was significantly reduced in patients receiving ETHYOL (TABLE 4).
At one year following radiation, whole saliva collection following radiation showed that more patients given ETHYOL produced >0.1 gm of saliva (72% vs. 49%). In addition, the median saliva production at one year was higher in those patients who received ETHYOL (0.26 gm vs. 0.1 gm). Stimulated saliva collections did not show a difference between treatment arms. These improvements in saliva production were supported by the patients' subjective responses to a questionnaire regarding oral dryness.
In the randomized head and neck cancer study, locoregional control, disease-free survival and overall survival were all comparable in the two treatment groups after one year of follow-up (see TABLE 5).
INDICATIONS AND USAGE
ETHYOL (amifostine) is indicated to reduce the cumulative renal toxicity associated with repeated administration of cisplatin in patients with advanced ovarian cancer.
ETHYOL is contraindicated in patients with known hypersensitivity to aminothiol compounds.
1. Effectiveness of the Cytotoxic Regimen
2. Effectiveness of Radiotherapy
Prior to ETHYOL infusion patients should be adequately hydrated. During ETHYOL 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 ETHYOL 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 ETHYOL 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 ETHYOL 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 ETHYOL 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
Allergic manifestations including anaphylaxis and severe cutaneous reactions have been associated with ETHYOL administration.
6. Nausea and Vomiting
Patients should be adequately hydrated prior to the ETHYOL infusion and blood pressure should be monitored (see DOSAGE AND ADMINISTRATION).
The safety of ETHYOL 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. ETHYOL should be used with particular care in these and other patients in whom the common ETHYOL adverse effects of nausea/vomiting and hypotension may be more likely to have serious consequences.
Prior to chemotherapy, ETHYOL 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, ETHYOL 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 may require permanent discontinuation of ETHYOL or urgent dermatologic consultation and biopsy (see below).
Cutaneous evaluation of the patient prior to each ETHYOL 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. ETHYOL should 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. ETHYOL 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 ETHYOL should be at the physician’s discretion based on medical judgment and appropriate dermatologic evaluation.
In case of severe acute allergic reactions ETHYOL should be immediately and permanently discontinued. Epinephrine and other appropriate measures should be available for treatment of serious allergic events such as anaphylaxis.
Special consideration should be given to the administration of ETHYOL in patients receiving antihypertensive medications or other drugs that could cause or potentiate hypotension.
Carcinogenesis, Mutagenesis, Impairment of Fertility
No long term animal studies have been performed to evaluate the carcinogenic potential of ETHYOL. ETHYOL 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 typhimurium strain 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. ETHYOL 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. ETHYOL 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 ETHYOL 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 ETHYOL.
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.
In the randomized study of patients with ovarian cancer given ETHYOL 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 ETHYOL 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 ETHYOL due to blood pressure reductions. In the randomized study of patients with head and neck cancer given ETHYOL at a dose of 200 mg/m2 prior to radiotherapy, hypotension was observed in 15% of patients treated. (see TABLE 6)
In the randomized study of patients with head and neck cancer, 17% (26/150) discontinued ETHYOL due to adverse events. All but one of these patients continued to receive radiation treatment until completion.
Hypotension that requires interruption of the ETHYOL 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 ETHYOL can
Nausea and/or vomiting occur frequently after ETHYOL infusion and may be severe.
Decrease in serum calcium concentrations is a known pharmacological effect of ETHYOL. At the recommended doses, clinically significant hypocalcemia was reported in 1% of patients in the randomized head and neck cancer study (see WARNINGS).
Other effects, which have been described during, or following ETHYOL 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 ETHYOL 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 ETHYOL is higher in patients receiving ETHYOL as a radioprotectant than in patients receiving ETHYOL 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 ETHYOL administration.
In clinical trials, the maximum single dose of ETHYOL 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 ETHYOL doses of up to 2700 mg/m2. At the higher doses, anxiety and reversible urinary retention occurred.
Administration of ETHYOL 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.
DOSAGE AND ADMINISTRATION
For Reduction of Cumulative Renal Toxicity with Chemotherapy:
The recommended starting dose of ETHYOL 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 ETHYOL 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 ETHYOL should be interrupted if the systolic blood pressure decreases significantly from the baseline value as listed in the guideline below:
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 ETHYOL may be administered. If the full dose of ETHYOL cannot be administered, the dose of ETHYOL 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 ETHYOL. 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 ETHYOL 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 ETHYOL 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 ETHYOL. Oral 5HT3 receptor antagonists, alone or in combination with other antiemetics, have been used effectively in the radiotherapy setting.
ETHYOL (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, ETHYOL 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).
ETHYOL 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.
ETHYOL (amifostine) for Injection is supplied as a sterile lyophilized powder in 10 mL single-use vials (NDC 58178-017-01). Each single-use vial contains 500 mg of amifostine on the anhydrous basis. The vials are available packaged as follows:
3 pack - 3 vials per carton (NDC 58178-017-03)
Store the lyophilized dosage form at Controlled Room Temperature 20°-25°C (68°-77°F) [See USP].
U.S. Patents 5,424,471; 5,591,731; 5,994,409
Ethyol® is a registered trademark of MedImmune, LLC.
For product information, please call 1 877 633 4411
Revision Date 1/2009 RAL-ETHV15
PRINCIPAL DISPLAY PANEL
500 mg per vial. Sterile
3 VIALS Rx only
Revised: 01/2009 MedImmune, LLC
Reproduced with permission of U.S. National Library of Medicine
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