cyclophosphamide, Cytoxan (cont.)

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DOSING: The usual initial dose of cytoxan for adults and children is 40-50 mg/kg administered intravenously over 2-5 days in divided doses. This dose may repeated at 2-4 week intervals. The usual oral dose is 1-5 mg/kg daily. Subsequent maintenance doses are adjusted based on the response of the tumor to treatment and the side effects.

DRUG INTERACTIONS: Allopurinol (Zyloprim) enhances the ability of cyclophosphamide to reduce production of blood cells from the bone marrow. (See below.) Cyclophosphamide increases the occurrence of heart failure that is caused by doxorubicin (Adriamycin), increases the action of blood thinners such as warfarin (Coumadin), and decreases the effectiveness of quinolone antibiotics (Cipro).

PREGNANCY: Use of cyclophosphamide during pregnancy may affect the fetus. Fetuses exposed to cyclophosphamide may be born with missing fingers, toes and a poorly-developed heart. Cyclophosphamide should not be administered during pregnancy.

NURSING MOTHERS: Cyclophosphamide is excreted in breast milk and could cause serious problems in the nursing infant.

SIDE EFFECTS: Side effects of cyclophosphamide include hair loss, vomiting, diarrhea, mouth sores, weight loss, sterility, and jaundice. Cyclophosphamide causes kidney failure, and it also may affect the heart and lungs. Cyclophosphamide suppresses production of blood cells from the bone marrow, including white blood cells (leukopenia), red blood cells (anemia) and platelets (thrombocytopenia). Leukopenia reduces the ability of the body to fight infection, thrombocytopenia impairs the ability of blood to clot, and anemia reduces the ability of blood to carry oxygen. Cyclophosphamide suppresses the immune system which may result in serious and sometimes fatal infections. Severe allergic reactions also may occur. Cyclophosphamide may cause inflammation of the urinary bladder with bleeding (hemorrhagic cystitis). This can result in lower abdominal pain from the bladder, problems urinating due to blood clots, and anemia due to loss of blood.

Reference: FDA Prescribing Information

Last Editorial Review: 1/4/2012

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