Group
Antiepileptic drug (hydantoin derivative)
Mechanism of Action
Stabilizes neuronal membranes by promoting sodium efflux and prolonging the inactive state of voltage-gated sodium channels, reducing repetitive neuronal firing.
Indications
- Generalized tonic-clonic seizures
- Complex partial seizures
- Prevention of seizures following neurosurgery or head trauma
- Status epilepticus (IV formulation)
Dose
- Adults (oral): 100 mg 2–3 times daily; adjust based on plasma levels (usual 300–600 mg/day).
- Adults (IV loading for status epilepticus): 15–20 mg/kg IV at 50 mg/min; maintenance 100 mg 3 times daily.
- Children: 5 mg/kg/day orally in 2–3 divided doses; titrate to response.
Major Side Effects
- Dizziness, nystagmus, ataxia
- Gingival hyperplasia
- Hirsutism, acne
- Rash, Stevens-Johnson syndrome (rare)
- Hepatotoxicity, blood dyscrasias (rare)
Contraindications
- Hypersensitivity to phenytoin
- Sinus bradycardia, heart block, or Adams-Stokes syndrome (IV use caution)
- Concurrent use with delavirdine (HIV drug)
Compatible Fluid
- IV: Normal saline only (avoid dextrose solutions – causes precipitation)
- Oral: Water or juice
Route of Administration
- Oral (tablet, suspension, chewable)
- Intravenous (IV) for status epilepticus
Type of Administration
Chronic therapy for seizure maintenance; IV used acutely for status epilepticus.