vincristin

Vincristine, also known as vincristin, is a vinca alkaloid chemotherapeutic agent derived from the Madagascar periwinkle plant Catharanthus roseus. It is used in combination regimens to treat a variety of cancers, particularly in children, including acute lymphoblastic leukemia, Wilms tumor, rhabdomyosarcoma, neuroblastoma, and some lymphomas.

Mechanism of action: Vincristine binds to beta-tubulin and inhibits microtubule polymerization, preventing the formation of the mitotic spindle. This disrupts mitosis and arrests cells in metaphase, producing an anti-proliferative effect.

Administration and pharmacokinetics: It is given by intravenous infusion. Intrathecal administration is strictly contraindicated and fatal. The drug is extensively distributed to tissues and is metabolized by hepatic cytochrome P450 3A4 (CYP3A4), with biliary excretion as a major route. Dosing is typically 1.4–2 mg/m2 per dose, with a maximum of 2 mg per administration; frequency depends on the regimen. Dosing may be adjusted in hepatic impairment, and drug interactions with CYP3A inhibitors or inducers can alter exposure.

Adverse effects and safety: The principal toxicity is neurotoxicity, including peripheral neuropathy and autonomic effects such as constipation. Myelosuppression is less common compared with other chemotherapies. Other risks include extravasation injury at the infusion site, fatigue, and alopecia. Vincristine requires careful administration practices to avoid intrathecal use and to manage dose-related toxicity within oncologic protocols.