Chemotherapy — Neurotoxic Agents
A client receiving vincristine reports tingling in their fingertips and new constipation. One of these can become life-threatening if you miss the connection to the drug.
Core Concept
Vincristine is a vinca alkaloid that works by binding tubulin and disrupting microtubule formation, which arrests cell division in metaphase. Its dose-limiting toxicity is peripheral neurotoxicity, not myelosuppression — a critical distinction from most other chemotherapy agents. Neurotoxicity is cumulative and presents in a predictable pattern: peripheral neuropathy appears first (numbness, tingling, loss of deep tendon reflexes starting in the fingers and toes), then autonomic neuropathy follows (constipation progressing to paralytic ileus, urinary retention, orthostatic hypotension). Constipation must be taken seriously — a paralytic ileus can become a surgical emergency. Vincristine is administered IV only and is fatal if given intrathecally. The maximum single adult dose is typically capped at 2 mg to limit neurotoxicity. You assess baseline neurological function before each cycle: grip strength, foot sensation, DTRs, and bowel patterns. A prophylactic bowel regimen (stool softeners, stimulant laxatives) should be initiated at treatment start, not after constipation develops.
Watch Out For
Don't confuse vincristine's dose-limiting toxicity (neurotoxicity) with most other chemo agents where myelosuppression is dose-limiting — vincristine causes relatively mild bone marrow suppression. Students mix up vincristine (neurotoxic) with vinblastine (myelosuppressive) — remember vincristine = nerves. Never confuse the IV-only route with intrathecal administration — intrathecal vincristine is universally fatal.
Clinical Pearl
VinCRISTINE = Cripples Nerves. If the client can't feel their feet or hasn't had a bowel movement, the vincristine is talking — listen.
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