Ifosfamide and mesna.

Abstract

The chemistry, pharmacology, pharmacokinetics, and adverse effects of ifosfamide and mesna are described separately, followed by a discussion of the adverse effects of concurrent ifosfamide and mesna, the clinical spectrum of ifosfamide, and the dosage and administration of the two drugs. Ifosfamide, an active analogue of cyclophosphamide, differs from other direct alkylating substances in that it requires biotransformation in the liver before it can exert its alkylating effects. The bioavailability of ifosfamide after oral administration exceeds 95%. The adverse effects of ifosfamide include hematologic, urinary tract, GI tract, and CNS toxicity. Mesna is a thiol compound designed to function as a regional detoxificant of urotoxic oxazaphosphorine cytostatics such as ifosfamide. The drug is rapidly oxidized in the plasma to its dimeric form, dimesna, one third of which is converted back to mesna by glutathione reductase. The mean total urinary availability of mesna administered orally is 76%. Mesna may produce gastrointestinal and allergic reactions. The adverse effects of concurrent ifosfamide and mesna include urinary tract and renal toxicity. Although current FDA-approved labeling is limited to refractory germ cell testicular cancer, ifosfamide has also shown efficacy in the treatment of lymphoma, lung cancer, and sarcomas. Optimum dosage and scheduling remain to be determined; studies suggest that a fractionated dosage schedule provides antineoplastic activity with tolerable toxicity. Ifosfamide, used in combination with mesna for uroprotection, provides a useful therapeutic option for the management of patients with testicular cancer, soft tissue sarcomas, or high-grade malignant lymphomas.