Which class includes vincristine and vinblastine, and what is a key toxicity?

• A. Anthracyclines; cardiotoxicity
• B. Vinca alkaloids; peripheral neuropathy
• C. Alkylating agents; nephrotoxicity
• D. Taxanes; myelosuppression

Answer: (B)

Vinca alkaloids include vincristine and vinblastine. They work by binding to tubulin and preventing microtubule polymerization, which stops cells from forming a proper mitotic spindle and halts them in metaphase during cell division. This mechanism explains why these drugs are effective against rapidly dividing cancer cells, but it also underlies their characteristic toxicities.

A key toxicity to remember for this class is peripheral neuropathy. Disruption of microtubules affects nerve cell function and axonal transport, leading to sensory and motor neuropathies. Vincristine, in particular, is well known for neurotoxicity as a dose-limiting adverse effect. While vinblastine can cause bone marrow suppression, the hallmark toxicity you’re expected to recognize for vinca alkaloids is peripheral neuropathy.