Vinblastine

What it is used for

• Susceptible neoplasms
• Susceptible neoplasms (e.g., mast cell tumors, lymphoma)
• Mast cell tumors (specific protocol)

How it is given

Possible side effects

• Gastroenterocolitis (nausea, vomiting, anorexia)
• Myelosuppression (neutropenia, thrombocytopenia, anemia; nadir at 4-9 days)
• Neurotoxicity (constipation, paralytic ileus, jaw and muscle pain, loss of deep tendon reflexes)
• Alopecia
• Stomatitis
• Syndrome of inappropriate ADH secretion (SIADH)
• Severe tissue irritation and cellulitis (if extravasated)
• Cats: Reversible axon swelling and paranodal demyelination
• Myelosuppression (primarily neutropenia)
• Gastrointestinal toxicity (vomiting, diarrhea, anorexia)
• Severe tissue necrosis (if extravasated)
• Myelosuppression (neutropenia, thrombocytopenia)

Cautions & contraindications

• Preexisting leukopenia or granulocytopenia (unless caused by the disease being treated)
• Active bacterial infection
• Neutrophil count < 3 x 10^9/L
• Platelet count < 100 x 10^9/L
• Pre-existing severe myelosuppression or active infection
• Pre-existing severe myelosuppression (Neutrophil count < 3 x 10^9/L or Platelet count < 100 x 10^9/L)
• > **Vesicant Warning:** Vinblastine is a severe tissue irritant. **Strict IV administration is required.** Avoid extravasation. Use a different needle for injection than the one used to draw up the drug. If extravasation occurs, stop immediately, apply moderate heat, and consider hyaluronidase injections to disperse the drug. * **MDR1 Mutation:** Dogs with the ABCB1 (MDR1) mutation (e.g., Collies, Australian Shepherds) are highly susceptible to toxicity. Reduce dose by 25-30% in mutant/normal or mutant/mutant dogs. * **Hepatic Impairment:** Extensive hepatic metabolism requires a 50% dose reduction if serum bilirubin is > 2 mg/dL. * **Handling:** Wear gloves and protective clothing during preparation and administration. Wash thoroughly with soap and water if skin exposure occurs. * **Pregnancy/Nursing:** Potentially teratogenic and embryotoxic (FDA Category D). Avoid in pregnant animals and use milk replacer if nursing.

Drug interactions

• Cisplatin: May cause additive risk for ototoxicity.
• Carboplatin: May cause additive risk for ototoxicity.
• P-glycoprotein inhibitors (e.g., Amiodarone, Ketoconazole, Cyclosporine, Diltiazem, Erythromycin, Spironolactone, Verapamil): Can inhibit P-glycoprotein clearance of vinblastine, increasing the risk of severe toxicity, particularly in dogs with the MDR1 (ABCB1) mutation.
• Cimetidine: Inhibits hepatic cytochrome P450 enzymes, potentially decreasing vinblastine metabolism and increasing toxicity.
• Other myelosuppressive agents: Additive bone marrow suppression.

Frequently asked questions