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Narrow therapeutic index anticonvulsant. NCLEX often tests CNS toxicity sequence, albumin correction, gingival hyperplasia, and IV compatibility.
Study aid - not medical advice. Not a clinical decision tool. Classic NCLEX Sheiner-Tozer uses 0.2; some modern references use other coefficients.
1. Check phenytoin level and symptoms together.
2. Assess neuro status; nystagmus is a classic early toxicity sign.
3. Check albumin before interpreting total phenytoin level.
4. For IV phenytoin, verify normal saline compatibility and ordered infusion rate.
Notify the provider for phenytoin level >20 mcg/mL, nystagmus, ataxia, slurred speech, rash, IV site pain/burning/discoloration, hypotension, bradycardia, or suspected toxicity.
Rash is high priority because of Stevens-Johnson/TEN risk.
Phenytoin level: 10-20 mcg/mL. Albumin matters because low albumin increases free active phenytoin.
Classic NCLEX correction: corrected = measured / [(0.2 × albumin) + 0.1]. Some modern calculators use different coefficients, but NCLEX commonly teaches the classic formula.
Watch LFTs and CBC.