Phenytoin Phil — Phenytoin: Narrow Range, Nystagmus & Gummy Smiles
Phenytoin stops his seizures at 10-20 — but nystagmus says the level is climbing, and his gums grow over his teeth
Phil has been seizure-free on phenytoin for a year. At his checkup his eyes beat side to side when he looks left, his gait is unsteady, his gums are swollen over his teeth, and his level is 26 mcg/mL.
Phil takes phenytoin for a seizure disorder, and phenytoin demands precision: the therapeutic range is only 10-20 mcg/mL, and small dose changes can push the level into toxicity because of nonlinear metabolism. The earliest toxicity signs are neurologic — nystagmus, ataxia, diplopia and slurred speech. Long-term, phenytoin causes gingival hyperplasia, so dental hygiene is a nursing priority. IV phenytoin has its own rule: give it no faster than 50 mg per minute in normal saline only, because rapid push causes cardiac dysrhythmias and it precipitates in dextrose. It also interacts with nearly everything, including reducing the effectiveness of oral contraceptives.
Read Phenytoin Phil's full story →The story arc
The setup
Phil starts phenytoin after a second seizure and learns the drug works only inside a narrow window — levels are drawn regularly to keep him between 10 and 20 mcg/mL.
The turn
Phil's wife notices his eyes darting back and forth and that he walks like he is drunk, though he has had nothing to drink.
The crisis
His level returns at 26 mcg/mL, his speech is slurred, and his swollen gums now bleed when he eats.
The save
The dose is adjusted to bring Phil back into range, he is referred for dental care with a soft-bristle brush and flossing routine, and he learns to never miss or double doses on his own.
NCLEX study section — Phenytoin: Narrow Range, Nystagmus & Gummy Smiles
What this chapter is testing: the recognition cues, the numbers and the priority action.
Study section: Pharmacology
Take this chapter into practice questions on the same topic.