رجل عمره ٣٥ سنة عنده صرع، يأخذ فينيتوين منذ سنوات وصرعه مضبوط. جاء للعيادة يشتكي أن لثته متورمة وتنزف عند التفريش، ومستوى الدواء لم يُقس منذ سنة. أي تعليمات تخص هذا الدواء؟

A 35-year-old man with epilepsy has taken phenytoin for years with good control. At clinic he reports swollen gums that bleed when brushing; his drug level has not been checked for a year. Which instructions relate to this drug?

1. Good dental and gum care and periodic drug-level checks
2. Take it with antacids to reduce stomach irritation
3. Stop it with any fever because it raises temperature
4. Avoid drinking water after the dose

Answer: A) Good dental and gum care and periodic drug-level checks. Phenytoin causes gingival hyperplasia, so good dental care is needed. It has a narrow therapeutic range, so levels are checked; toxicity shows as nystagmus, ataxia and drowsiness. Antacids reduce absorption.