cyclophosphamide (Cytoxan) Cancer Drug Side Effects

What is cyclophosphamide? How does it work (mechanism of action)?

Cyclophosphamide is a drug that is used primarily for treating several types of cancer. In order to work, cyclophosphamide first is converted by the liver into two chemicals, acrolein and phosphoramide. Acrolein and phosphoramide are the active compounds, and they slow the growth of cancer cells by interfering with the actions of deoxyribonucleic acid (DNA) within the cancerous cells. Unfortunately, normal cells also are affected, and this results in serious side effects. In addition to slowing the growth of cancerous cells, cyclophosphamide also suppresses the immune system and is referred to as immunosuppressive.

The FDA approved Cytoxan in November 1959.

What are the uses for cyclophosphamide?

Cyclophosphamide is used alone for the treatment of several types of cancers, but often in combination with other drugs to treat

• breast cancer,
• leukemia,
• ovarian cancer, and
• nephrotic syndrome (a disease of the kidneys) in children.

Unapproved uses include the treatment of

• granulomatosis with polyangiitis,
• severe rheumatoid arthritis,
• lupus erythematosus,
• advanced mycosis fungoides, and
• several of forms of vasculitis.

What are the side effects of cyclophosphamide?

Side effects of cyclophosphamide include:

• Hair loss
• Nausea
• Vomiting
• Diarrhea
• Mouth sores
• Weight loss
• Stomach pain
• Rash
• Mouth sores (stomatitis)
• Skin pigmentation
• Nail changes
• Sterility
• 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.

What is the dosage for cyclophosphamide?

The usual initial dose of cyclophosphamide 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.

Which drugs or supplements interact with cyclophosphamide?

Allopurinol (Zyloprim) enhances the ability of cyclophosphamide to reduce production of blood cells from the bone marrow.

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 ciprofloxacin (Cipro, Cipro XR, Proquin XR).

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Is cyclophosphamide safe to take if I’m pregnant or breastfeeding?

• 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.
• Cyclophosphamide is excreted in breast milk and could cause serious problems in the nursing infant.

What else should I know about cyclophosphamide?

Cyclophosphamide is available as:

• Powder for intravenous injection: 100, 200, 500, 1000, and 2000 mg)
• Tablets: 25, 50 mg.

Powder and tablets should be stored at room temperature, 15 C – 30 C (59 F – 86 F). Solutions prepared with bacteriostatic water are usable up to 24 hours if stored at room temperature and up to 6 days if stored in the refrigerator.

Cyclophosphamide is available in generic form, and you need a prescription to obtain it.