Cyclophosphamide

Cyclophosphamide: Uses, Dosage and Side Effects

Overview

Cross-linking of DNA by metabolic byproducts inhibits both DNA synthesis and its activity.

Uses of Cyclophosphamide

• Treatment of lymphoproliferative and myeloproliferative diseases.
• May play a role in the treatment of certain sarcomas and carcinomas when used in metronomic chemotherapy protocols.

Dose of Cyclophosphamide in Dogs and Cats

Dogs:

• Lymphoid neoplasia: generally 50 mg/m2 p.o. q48h or 3–4 consecutive days/week; or 200–250 mg/m2 p.o or i.v. q3wk.
• Metronomic chemotherapy: 10–15 mg/m2 p.o. q24h.
• Multiple myeloma in patients refractory to melphalan: 1 mg/kg p.o. q24h.
• Macroglobulinaemia in patients refractory to chlorambucil: 1 mg/kg p.o. q24h.

Cats:

Lymphoid neoplasia: as for dogs, except 200–300 mg/m2 in ‘high dose’ COP regimes.

Side Effects of Cyclophosphamide in Dogs and Cats

• Myelosuppression, with the nadir usually 5–14 days after therapy so, WBC monitoring is advised.
• A cyclophosphamide metabolite (acrolein) can induce sterile hemorrhagic cystitis.
• Persistent cystitis can cause bladder fibrosis and transitional cell carcinoma.
• Water consumption and furosemide can lower this risk by increasing urine production.
• Vomiting, diarrhea, hepatotoxicity, nephrotoxicity, pulmonary infiltrates and fibrosis, and hair growth reduction are also consequences.

Contraindications of Cyclophosphamide in Dogs and Cats

No information is available.

Some Notes:

• Use with caution in patients with kidney failure; the dose may need to be lowered.
• Cyclophosphamide is no longer recommended as a drug to suppress the immune system.
• Concomitant thiazide diuretics increase myelosuppression risk.
• Oral digoxin absorption may reduce days after dosing.
• Barbiturates enhance cyclophosphamide toxicity by metabolizing faster.