Antiepileptic drugs (AEDs)

Pick by seizure type; know pregnancy safety and the dirty toxicities.

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◆By seizure type

•Focal seizures: carbamazepine, oxcarbazepine, lamotrigine, levetiracetam, lacosamide
•Generalized tonic-clonic: valproate, lamotrigine, levetiracetam, topiramate
•Absence: ETHOSUXIMIDE first-line; valproate alternative
•Status epilepticus: lorazepam IV → phenytoin/fosphenytoin or levetiracetam → midazolam/propofol/pentobarbital infusion
•Myoclonic / Juvenile myoclonic epilepsy: valproate (or levetiracetam in women)

•AVOID: valproate (neural tube defects, ↓ IQ), carbamazepine (NTD), phenytoin (fetal hydantoin syndrome), topiramate (cleft palate)
•Safer: lamotrigine, levetiracetam — preferred in women of childbearing age
•All pregnant women on AEDs: high-dose folic acid (4 mg/day) preconception and 1st trimester

•Phenytoin: gingival hyperplasia, hirsutism, ataxia, nystagmus, megaloblastic anemia, drug-induced lupus, SJS, osteopenia, zero-order kinetics
•Carbamazepine: SIADH, agranulocytosis, aplastic anemia, SJS (HLA-B*1502 in Asians), hepatotoxic, induces CYP
•Valproate: hepatotoxicity, pancreatitis, weight gain, alopecia, hyperammonemia, thrombocytopenia, NTD in pregnancy
•Lamotrigine: Stevens-Johnson syndrome (titrate slowly — esp with valproate)
•Levetiracetam: irritability, behavioral changes, depression
•Topiramate: word-finding difficulty, weight loss, kidney stones, oligohidrosis
•Phenobarbital: sedation, dependence, induces CYP

◆Lamotrigine + valproate → SJS risk ↑↑ (valproate inhibits lamotrigine metabolism); titrate very slowly
◆Phenytoin + tube feeds → ↓ absorption; hold feeds 1–2 hr around dose
◆Childbearing woman on AED → lamotrigine or levetiracetam + folic acid 4 mg
◆Status epilepticus first line: IV lorazepam (or buccal midazolam if no IV)
◆Carbamazepine for Asian patients → HLA-B*1502 test (SJS risk)

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