A nurse reviews a serum phenytoin level of 24 mcg/mL in a client receiving the drug for tonic-clonic seizures. Which clinical findings would the nurse expect to assess?

1 Nystagmus, ataxia, slurred speech, and confusion ✓ Correct answer
2 Hypertension, bradycardia, and pinpoint pupils
3 Increased salivation and bronchospasm
4 Hyperreflexia and clonus

Explanation

Correct (1): The therapeutic range is 10-20 mcg/mL. At >20: nystagmus is the earliest sign, followed by ataxia, slurred speech, and confusion. At >30-40: lethargy and coma. (2) These describe opioid toxicity. (3) Hyperreflexia/clonus suggests serotonin syndrome or hyperthyroidism. (4) Cholinergic crisis findings.

In-depth explanation

Memory Tip Phenytoin toxicity ladder: 20+ nystagmus → 30+ ataxia → 40+ lethargy/coma. CPG Albumin-correct the level in hypoalbuminemic clients to avoid false-low reading.

Clinical scenario

Scenario 45-year-old male on phenytoin 300 mg PO daily × 6 weeks. Trough serum level today: 24 mcg/mL (therapeutic range 10-20). He reports the room "feels wobbly."

Key concepts

Therapeutic range — Serum drug concentration that balances efficacy and toxicity; phenytoin: 10-20 mcg/mL.
Nystagmus — Involuntary rhythmic eye movement; earliest clinical sign of phenytoin toxicity.
Narrow therapeutic index — A small margin between therapeutic and toxic doses; phenytoin requires regular level monitoring.

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A nurse reviews a serum phenytoin level of 24 mcg/mL in a client receiving the drug for tonic-clonic seizures. Which clinical findings would the nurse expect to assess?

In-depth explanation

Clinical scenario

Key concepts

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