Ifosfamide – Ifex®

Ifosfamide (Ifex)

Usual Diluents

Dilution Data

Administration: 1
In order to prevent bladder toxicity, IFEX should be given with extensive hydration consisting of at least 2 liters of oral or intravenous fluid per day. A protector, such as mesna, should also be used to prevent hemorrhagic cystitis. IFEX should be administered as a slow intravenous infusion lasting a minimum of 30 minutes.

Preparation for Intravenous Administration/Stability 1
Injections are prepared for parenteral use by adding Sterile Water for Injection, USP, or Sterile Bacteriostatic Water for Injection, USP (benzyl alcohol or parabens preserved), to the vial and shaking to dissolve. Use the quantity of diluent shown below to constitute the product:

Solutions of ifosfamide may be diluted further to achieve concentrations of 0.6 to 20 mg/mL (50 - 1000 ml) in the following fluids:
5% Dextrose Injection, USP
0.9% Sodium Chloride Injection, USP
Lactated Ringer's Injection, USP
Sterile Water for Injection, USP

Because essentially identical stability results were obtained for Sterile Water admixtures as for the other admixtures (5% Dextrose Injection, 0.9% Sodium Chloride Injection, and Lactated Ringer's Injection), the use of large volume parenteral glass bottles, Viaflex bags or PAB™ bags that contain intermediate concentrations or mixtures of excipients (eg, 2.5% Dextrose Injection, 0.45% Sodium Chloride Injection, or 5% Dextrose and 0.9% Sodium Chloride Injection) is also acceptable.1

Stability / Storage:
Constituted or constituted and further diluted solutions of IFEX should be refrigerated and used within 24 hours.     Store intact vials (powder for solution) at controlled room temperature 20°C to 25°C (68°F to 77°F).   Store intact vials of solution under refrigeration at 2°C to 8°C (36°F to 46°F).1

Other reference 2:   Solutions diluted for administration are stable for 7 days at room temperature and for 6 weeks under refrigeration.   Reconstituted solutions may be stored under refrigeration for up to 21 days.

DESCRIPTION
IFEX (ifosfamide for injection, USP) single-dose vials for constitution and administration by intravenous infusion each contain 1 gram or 3 grams of sterile ifosfamide. Ifosfamide is a chemotherapeutic agent chemically related to the nitrogen mustards and a synthetic analog of cyclophosphamide. Ifosfamide is 3-(2-chloroethyl)-2-[(2-chloroethyl)amino]tetrahydro-2H-1,3,2-oxazaphosphorine 2-oxide. The molecular formula is C7H15Cl2N2O2P and its molecular weight is 261.

CLINICAL PHARMACOLOGY
Ifosfamide has been shown to require metabolic activation by microsomal liver enzymes to produce biologically active metabolites. Activation occurs by hydroxylation at the ring carbon atom 4 to form the unstable intermediate 4-hydroxyifosfamide. This metabolite rapidly degrades to the stable urinary metabolite 4-ketoifosfamide. Opening of the ring results in formation of the stable urinary metabolite, 4-carboxyifosfamide. These urinary metabolites have not been found to be cytotoxic. N, N-bis (2-chloroethyl)-phosphoric acid diamide (ifosphoramide) and acrolein are also found. Enzymatic oxidation of the chloroethyl side chains and subsequent dealkylation produces the major urinary metabolites, dechloroethyl ifosfamide and dechloroethyl cyclophosphamide. The alkylated metabolites of ifosfamide have been shown to interact with DNA.

In vitro incubation of DNA with activated ifosfamide has produced phosphotriesters. The treatment of intact cell nuclei may also result in the formation of DNA-DNA cross-links. DNA repair most likely occurs in G-1 and G-2 stage cells.

Pharmacokinetics
Ifosfamide exhibits dose-dependent pharmacokinetics in humans. At single doses of 3.8-5.0 g/m2, the plasma concentrations decay biphasically and the mean terminal elimination half-life is about 15 hours. At doses of 1.6-2.4 g/m2/day, the plasma decay is monoexponential and the terminal elimination half-life is about 7 hours.

Ifosfamide is extensively metabolized in humans and the metabolic pathways appear to be saturated at high doses.

After administration of doses of 5 g/m2 of 14C-labeled ifosfamide, from 70% to 86% of the dosed radioactivity was recovered in the urine, with about 61% of the dose excreted as parent compound. At doses of 1.6-2.4 g/m2 only 12% to 18% of the dose was excreted in the urine as unchanged drug within 72 hours.

Two different dechloroethylated derivatives of ifosfamide, 4-carboxyifosfamide, thiodiacetic acid and cysteine conjugates of chloroacetic acid have been identified as the major urinary metabolites of ifosfamide in humans and only small amounts of 4-hydroxyifosfamide and acrolein are present. Small quantities (nmole/mL) of ifosfamide mustard and 4-hydroxyifosfamide are detectable in human plasma. Metabolism of ifosfamide is required for the generation of the biologically active species and while metabolism is extensive, it is also quite variable among patients.

In a study at Indiana University, 50 fully evaluable patients with germ cell testicular cancer were treated with IFEX in combination with cisplatin and either vinblastine or etoposide after failing (47 of 50 patients) at least two prior chemotherapy regimens consisting of cisplatin/vinblastine/bleomycin, (PVB), cisplatin/vinblastine/actinomycin D/bleomycin/cyclophosphamide, (VAB6), or the combination of cisplatin and etoposide. Patients were selected for remaining cisplatin sensitivity because they had previously responded to a cisplatin containing regimen and had not progressed while on the cisplatin containing regimen or within 3 weeks of stopping it. Patients served as their own control based on the premise that long term complete responses could not be achieved by retreatment with a regimen to which they had previously responded and subsequently relapsed.

Ten of 50 fully evaluable patients were still alive 2 to 5 years after treatment. Four of the 10 long term survivors were rendered free of cancer by surgical resection after treatment with the ifosfamide regimen; median survival for the entire group of 50 fully evaluable patients was 53 weeks.

INDICATIONS AND USAGE
IFEX, used in combination with certain other approved antineoplastic agents, is indicated for third line chemotherapy of germ cell testicular cancer. It should ordinarily be used in combination with a prophylactic agent for hemorrhagic cystitis, such as mesna.

CONTRAINDICATIONS
Continued use of IFEX is contraindicated in patients with severely depressed bone marrow function (see WARNINGS and PRECAUTIONS sections). IFEX is also contraindicated in patients who have demonstrated a previous hypersensitivity to it.

WARNINGS
Urinary System
Urotoxic side effects, especially hemorrhagic cystitis, have been frequently associated with the use of IFEX.

It is recommended that a urinalysis should be obtained prior to each dose of IFEX. If microscopic hematuria (greater than 10 RBCs per high power field), is present, then subsequent administration should be withheld until complete resolution.

Further administration of IFEX should be given with vigorous oral or parenteral hydration.

Hematopoietic System
When IFEX is given in combination with other chemotherapeutic agents, severe myelosuppression is frequently observed. Close hematologic monitoring is recommended. White blood cell (WBC) count, platelet count and hemoglobin should be obtained prior to each administration and at appropriate intervals. Unless clinically essential, IFEX should not be given to patients with a WBC count below 2000/µL and/or a platelet count below 50,000/µL.

Central Nervous System
Neurologic manifestations consisting of somnolence, confusion, hallucinations and in some instances, coma, have been reported following IFEX therapy. The occurrence of these symptoms requires discontinuing IFEX therapy. The symptoms have usually been reversible and supportive therapy should be maintained until their complete resolution.

Pregnancy
Animal studies indicate that the drug is capable of causing gene mutations and chromosomal damage in vivo. Embryotoxic and teratogenic effects have been observed in mice, rats and rabbits at doses 0.05 to 0.075 times the human dose. Ifosfamide can cause fetal damage when administered to a pregnant woman. If IFEX is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.

DOSAGE AND ADMINISTRATION
IFEX should be administered intravenously at a dose of 1.2 g/m2 per day for 5 consecutive days. Treatment is repeated every 3 weeks or after recovery from hematologic toxicity (Platelets ≥100,000/µL, WBC ≥4,000/µL).

In order to prevent bladder toxicity, IFEX should be given with extensive hydration consisting of at least 2 liters of oral or intravenous fluid per day. A protector, such as mesna, should also be used to prevent hemorrhagic cystitis. IFEX should be administered as a slow intravenous infusion lasting a minimum of 30 minutes. Although IFEX has been administered to a small number of patients with compromised hepatic and/or renal function, studies to establish optimal dose schedules of IFEX in such patients have not been conducted.

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Preparation for Intravenous Administration/Stability
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Injections are prepared for parenteral use by adding Sterile Water for Injection, USP, or Sterile Bacteriostatic Water for Injection, USP (benzyl alcohol or parabens preserved), to the vial and shaking to dissolve. Use the quantity of diluent shown below to constitute the product:

Solutions of ifosfamide may be diluted further to achieve concentrations of 0.6 to 20 mg/mL in the following fluids:

5% Dextrose Injection, USP

0.9% Sodium Chloride Injection, USP

Lactated Ringer's Injection, USP

Sterile Water for Injection, USP

Because essentially identical stability results were obtained for Sterile Water admixtures as for the other admixtures (5% Dextrose Injection, 0.9% Sodium Chloride Injection, and Lactated Ringer's Injection), the use of large volume parenteral glass bottles, Viaflex bags or PAB™ bags that contain intermediate concentrations or mixtures of excipients (eg, 2.5% Dextrose Injection, 0.45% Sodium Chloride Injection, or 5% Dextrose and 0.9% Sodium Chloride Injection) is also acceptable.

Constituted or constituted and further diluted solutions of IFEX should be refrigerated and used within 24 hours.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration.

HOW SUPPLIED
IFEX (ifosfamide for injection, USP) is available in single-dose vials as follows:

IFEX (ifosfamide for injection).

NDC 0338-3991-01 1-gram Single-Dose Vial

NDC 0338-3993-01 3-gram Single-Dose Vial

Store at controlled room temperature 20°C to 25°C (68°F to 77°F).

Protect from temperatures above 30°C (86°F).

Procedures for proper handling and disposal of anticancer drugs should be considered. Skin reactions associated with accidental exposure to IFEX may occur. The use of gloves is recommended. If IFEX solution contacts the skin or mucosa, immediately wash the skin thoroughly with soap and water or rinse the mucosa with copious amounts of water. Several guidelines on this subject have been published.1-7 There is no general agreement that all of the procedures recommended in the guidelines are necessary or appropriate.

2) Solimando, Dominic A. Drug Information Handbook for Oncology: A Complete Guide to Combination Chemotherapy Regimens, 8th ed. Hudson, OH: Lexi-Comp, Inc.; 2010.

Procedures for proper handling and disposal: Recommendations for the Safe Handling of Parenteral Antineoplastic Drugs. NIH Publication No. 83-2621. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402. AMA Council Report. Guidelines for Handling Parenteral Antineoplastics. JAMA  1985; 253 (11):1590-1592. National Study Commission on Cytotoxic Exposure–Recommendations for Handling Cytotoxic Agents. Available from Louis P. Jeffrey, Sc.D., Chairman, National Study Commission on Cytotoxic Exposure, Massachusetts College of Pharmacy and Allied Health Sciences, 179 Longwood Avenue, Boston, Massachusetts 02115. Clinical Oncological Society of Australia: Guidelines and Recommendations for Safe Handling of Antineoplastic Agents. Med J Australia  1983; 1:426-428. Jones, RB, et al: Safe Handling of Chemotherapeutic Agents: A Report from the Mount Sinai Medical Center. CA–A Cancer Journal for Clinicians  1983; (Sept./Oct.)258-263. American Society of Hospital Pharmacists Technical Assistance Bulletin on Handling Cytotoxic and Hazardous Drugs. Am J Hosp Pharm  1990; 47:1033-1049. Controlling Occupational Exposure to Hazardous Drugs. (OSHA WORK-PRACTICE GUIDELINES). Am J Health-Syst Pharm  1996; 53:1669-1685