Antiepileptic drug selection requires understanding both seizure type and drug mechanism — a high-yield area.
Mechanism classes
- Na+ channel: phenytoin, carbamazepine, lamotrigine
- T-type Ca2+ channel: ethosuximide, valproate — absence seizures
- GABA enhancement: benzodiazepines, barbiturates, vigabatrin
- SV2A binding: levetiracetam — broad spectrum
Drug of choice
- Absence: ethosuximide (valproate)
- Generalised tonic-clonic: valproate, levetiracetam
- Focal: carbamazepine, lamotrigine, levetiracetam
- Status epilepticus: IV lorazepam → phenytoin/fosphenytoin → phenobarbitone
Valproate is the broadest-spectrum AED but is teratogenic — avoid in women of childbearing potential where alternatives exist.