The nurse in the neurology clinic is caring for a group of clients receiving phenytoin.
Which client is at the greatest risk for phenytoin toxicity? A client with epilepsy who also
The nurse in the neurology clinic is caring for a group of clients receiving phenytoin.
Which client is at the greatest risk for phenytoin toxicity? A client with epilepsy who also
A. has hypertension and is taking a thiazide diuretic.
[42%]
B. is malnourished and is taking a bisphosphonate.
[30%]
C. smokes cigarettes daily and is being treated for acute sinusitis with azithromycin.
[23%]
D. has diabetes mellitus (type two) and just started short-acting insulin injections.
[5%]
Statistics
Subject/Lesson
Subject
Pharmacology
Lesson
Neurologic
Client Need
Test Plan
Pharmacological and Parenteral Therapies
Related Topic
Adverse Effects/Contraindications/Side Effects/Interactions
Item Type
Item Type
Application
Explanation
Choice B is correct. A malnourished client is at increased risk for phenytoin toxicity due to decreased albumin levels, which reduce protein binding and increase free (active) phenytoin levels. Bisphosphonate use does not directly contribute to toxicity, but malnutrition alone is a significant risk factor.
Choice A is incorrect. Thiazide diuretics and hypertension do not affect hepatic metabolism or albumin levels, making toxicity from phenytoin less likely.
Choice C is incorrect. Cigarette smoking can induce hepatic enzymes, potentially lowering phenytoin levels rather than increasing them; sinusitis treatment is unlikely to cause toxicity.
Choice D is incorrect: Diabetes mellitus (type two) and insulin use do not significantly alter phenytoin pharmacokinetics or protein binding to cause toxicity.
Related Videos
2 Key Topics
Anticonvulsants (Phenytoin)
16.3 Neuro Pharmacology
Additional Info
✓ Phenytoin is an antiepileptic drug approved for epilepsy. Its popularity has declined in recent decades because of its side effect profile.
✓ Phenytoin is highly protein-bound (~90%); hypoalbuminemia increases the free drug fraction.
✓ Free phenytoin levels are more clinically relevant in malnourished or critically ill patients.
✓ Total phenytoin levels can appear normal even when free levels are toxic in hypoalbuminemia.
✓ Signs of toxicity include ataxia, nystagmus, lethargy, and confusion, even at standard doses.
