Cytoxan (cyclophosphamide)

Treating certain types of the following cancers: lymphoma, multiple myeloma, leukemia, mycosis fungoides, neuroblastoma, ovarian cancer, eye cancer, and breast cancer. It is usually used in combination with other medicines. It may also be used to treat certain kidney problems (nephrotic syndrome) in children or for other conditions as determined by your doctor.

Cytoxan is an antineoplastic. It works by stopping or slowing the growth or spread of certain cancer cells.

Generic Name: cyclophosphamide
Dosage Form: Injection

Cytoxan Description

Cytoxan® (cyclophosphamide for injection, USP) is a sterile white powder containing cyclophosphamide monohydrate. Cytoxan Tablets (cyclophosphamide tablets, USP) are for oral use and contain 25 mg or 50 mg cyclophosphamide (anhydrous). Inactive ingredients in Cytoxan Tablets are: acacia, FD&C Blue No. 1, D&C Yellow No. 10 Aluminum Lake, lactose, magnesium stearate, starch, stearic acid and talc. Cyclophosphamide is a synthetic antineoplastic drug chemically related to the nitrogen mustards. Cyclophosphamide is a white crystalline powder with the molecular formula C7H15Cl2N2O2P•H2O and a molecular weight of 279.1. The chemical name for cyclophosphamide is 2-[bis(2-chloroethyl)amino]tetrahydro-2H-1,3,2-oxazaphosphorine 2-oxide monohydrate. Cyclophosphamide is soluble in water, saline, or ethanol and has the following structural formula:

Cytoxan - Clinical Pharmacology

Cyclophosphamide is biotransformed principally in the liver to active alkylating metabolites by a mixed function microsomal oxidase system. These metabolites interfere with the growth of susceptible rapidly proliferating malignant cells. The mechanism of action is thought to involve cross-linking of tumor cell DNA.

Indications and Usage for Cytoxan

Malignant Diseases

Cytoxan, although effective alone in susceptible malignancies, is more frequently used concurrently or sequentially with other antineoplastic drugs. The following malignancies are often susceptible to Cytoxan treatment:

1. Malignant lymphomas (Stages III and IV of the Ann Arbor staging system), Hodgkin’s disease, lymphocytic lymphoma (nodular or diffuse), mixed-cell type lymphoma, histiocytic lymphoma, Burkitt’s lymphoma.
2. Multiple myeloma.
3. Leukemias: Chronic lymphocytic leukemia, chronic granulocytic leukemia (it is usually ineffective in acute blastic crisis), acute myelogenous and monocytic leukemia, acute lymphoblastic (stem-cell) leukemia in children (Cytoxan given during remission is effective in prolonging its duration).
4. Mycosis fungoides (advanced disease).
5. Neuroblastoma (disseminated disease).
6. Adenocarcinoma of the ovary.
7. Retinoblastoma.
8. Carcinoma of the breast.

Nonmalignant Disease
Biopsy Proven “Minimal Change” Nephrotic Syndrome in Children

Cytoxan is useful in carefully selected cases of biopsy proven “minimal change” nephrotic syndrome in children but should not be used as primary therapy. In children whose disease fails to respond adequately to appropriate adrenocorticosteroid therapy or in whom the adrenocorticosteroid therapy produces or threatens to produce intolerable side effects, Cytoxan may induce a remission. Cytoxan is not indicated for the nephrotic syndrome in adults or for any other renal disease.

Cytoxan Dosage and Administration

Treatment of Malignant Diseases
Adults and Children

When used as the only oncolytic drug therapy, the initial course of Cytoxan for patients with no hematologic deficiency usually consists of 40 to 50 mg/kg given intravenously in divided doses over a period of 2 to 5 days. Other intravenous regimens include 10 to 15 mg/kg given every 7 to 10 days or 3 to 5 mg/kg twice weekly.

Oral Cytoxan dosing is usually in the range of 1 to 5 mg/kg/day for both initial and maintenance dosing.

Many other regimens of intravenous and oral Cytoxan have been reported. Dosages must be adjusted in accord with evidence of antitumor activity and/or leukopenia. The total leukocyte count is a good, objective guide for regulating dosage. Transient decreases in the total white blood cell count to 2000 cells/mm3 (following short courses) or more persistent reduction to 3000 cells/mm3 (with continuing therapy) are tolerated without serious risk of infection if there is no marked granulocytopenia.

When Cytoxan is included in combined cytotoxic regimens, it may be necessary to reduce the dose of Cytoxan as well as that of the other drugs.

Cytoxan and its metabolites are dialyzable although there are probably quantitative differences depending upon the dialysis system being used. Patients with compromised renal function may show some measurable changes in pharmacokinetic parameters of Cytoxan metabolism, but there is no consistent evidence indicating a need for Cytoxan dosage modification in patients with renal function impairment.