Medical Management of Epilepsy
Core concepts
Antiseizure medications (ASMs) are chosen by seizure type, epilepsy syndrome, comorbidities, age, sex, and drug interactions. Mechanisms: sodium channel blockade (carbamazepine, oxcarbazepine, lamotrigine, phenytoin, lacosamide), GABA enhancement (benzodiazepines, phenobarbital, vigabatrin), calcium channel (T-type) blockade (ethosuximide), and mixed/multimodal (valproate, topiramate, levetiracetam).
Drug selection by syndrome
- Focal onset: carbamazepine, oxcarbazepine, lamotrigine, levetiracetam, lacosamide.
- Generalized onset (including absence): valproate, lamotrigine, ethosuximide (absence).
- Avoid sodium channel blockers in Dravet; avoid valproate in women of childbearing age when alternatives exist (teratogenicity, neurodevelopmental risk).
Key adverse effects and interactions
- Valproate: hepatotoxicity, hyperammonemia, weight gain, tremor, teratogenicity.
- Lamotrigine: rash/Stevens-Johnson (titrate slowly, especially with valproate).
- Carbamazepine: hyponatremia, aplastic anemia, enzyme induction.
- Phenytoin: zero-order kinetics, gingival hyperplasia, ataxia.
- Levetiracetam: behavioral changes.
Status epilepticus
Benzodiazepines first (lorazepam, midazolam), then a second-line ASM (fosphenytoin, valproate, levetiracetam), then anesthetic agents (midazolam, propofol, pentobarbital) for refractory cases.
Traps
- Using ethosuximide for generalized tonic-clonic seizures (it treats absence only).
- Missing enzyme induction (carbamazepine, phenytoin) reducing oral contraceptive efficacy.
- Forgetting slow titration of lamotrigine to avoid rash.
Rule of thumb
Monotherapy, start low, go slow; match drug to seizure type and patient factors.