#Drug #Neurology

Phenytoin

evan April 9, 2024

Drug Class	Anti-convulsant
Mechanism	Alters transmembrane movement of Na+/K+ by blocking voltage-gated Na+ channels - prevents spread of epileptic discharges
Typical Dose	3-4mg/kg daily
Indications	Epilepsy (all except absence seizure) Trigeminal neuralgia
Contra-indications	Acute porphyrias
Side-effects	Common: dizziness, headache, confusion, insomnia, nausea, vomiting, hirsutism Rarely: gum hypertrophy, rash, Stevens-Johnson syndrome, drug-induced SLE
Interactions	Induces hepatic drug-metabolising enzymes: Amiodarone, aspirin, cimetidine, diltazem, nifedipine OCP - increased metabolism of OCP Rifampicin - plasma concentration of phenytoin Warfarin - increased metabolism of warfarin
Elimination
Additional Notes