Vinblastine

Class: Vinca alkaloid (microtubule inhibitor)

Formulation: IV only (vesicant; NEVER intrathecal – fatal).

Mechanism of Action (MOA):

• Binds to β-tubulin, preventing microtubule polymerization.
• Blocks spindle fiber formation → arrests cells in M phase.
• Causes mitotic arrest → apoptosis.

Indications:

• Hodgkin lymphoma (ABVD regimen: Adriamycin, Bleomycin, Vinblastine, Dacarbazine).
• Non-Hodgkin lymphoma.
• Testicular cancer (in combination with cisplatin and bleomycin – PVB regimen).
• Breast cancer, Kaposi’s sarcoma, bladder cancer, histiocytosis (less common).

Dosing:

• IV only, typically 6 mg/m² every 1–2 weeks depending on regimen.
• Adjust dose for hepatic impairment (bilirubin-based reduction).
• No renal adjustment needed.

Toxicities:

🔹 Dose-limiting toxicity: Myelosuppression

• Leukopenia > thrombocytopenia.
• Monitor CBC closely.

🔹 Other adverse effects:

• Mild peripheral neuropathy (less severe than vincristine).
• Constipation and GI effects (less pronounced vs. vincristine).
• Alopecia.
• SIADH (rare).
• Vesicant → extravasation risk.

Contraindications / Warnings:

• Never administer intrathecally (fatal).
• Dose reduce in hepatic dysfunction.
• Avoid with strong CYP3A4 inhibitors/inducers (azole antifungals, macrolides, protease inhibitors).

Clinical Pearls for Pharmacists:

• Key difference vs. Vincristine:
  • Vinblastine → bone marrow suppression (myelosuppression) is dose-limiting.
  • Vincristine → neurotoxicity is dose-limiting.
• Ensure correct handling and labeling to prevent intrathecal error.
• Educate patients about infection risk (neutropenia precautions).
• Used mainly in Hodgkin’s lymphoma (ABVD) and testicular cancer regimens.

Would you like me to build a side-by-side comparison table of Vincristine, Vinblastine, and Vinorelbine (MOA, dosing, dose-limiting toxicity, clinical pearls) so you can use it as a quick reference in practice?