Antiepileptics (adult)
also: sodium valproate · lamotrigine · carbamazepine · levetiracetam · phenytoin · AED
Overview
Maintenance antiepileptics by seizure type, with the drug-specific safety points (valproate teratogenicity, lamotrigine/carbamazepine SJS, enzyme induction). Cross-references the paediatric seizure card.
Mechanism
Most stabilise voltage-gated Na⁺ channels (valproate, lamotrigine, carbamazepine, phenytoin) reducing repetitive firing; valproate also ↑GABA; ethosuximide blocks thalamic T-type Ca²⁺ channels (absence); levetiracetam binds SV2A.
Indications
- Focal seizures (lamotrigine/levetiracetam first-line)
- Generalised tonic-clonic (sodium valproate; lamotrigine/levetiracetam)
- Absence (ethosuximide)
- Status epilepticus (benzo → levetiracetam/phenytoin)
The agents
TERATOGENIC (NTD, ↓IQ) — pregnancy prevention programme; weight gain, tremor, hepatotoxicity, hair loss, pancreatitis; enzyme INHIBITOR.
slow titration
Preferred in women of childbearing potential; Stevens-Johnson syndrome (slow titration; valproate raises levels/SJS risk).
Enzyme INDUCER (↓OCP, autoinduction); SJS (HLA-B*1502), hyponatraemia (SIADH); worsens absence/myoclonic.
Well tolerated; behavioural/mood effects.
zero-order kinetics
Gum hypertrophy, ataxia, nystagmus; narrow index — monitor levels.
First-line absence seizures.
Adverse effects
Cautions & contraindications
Teratogen — only under a pregnancy-prevention programme.
Exacerbates them.
Precipitates seizures/status.
Interactions
- Carbamazepine/phenytoin induce CYP (↓OCP — counsel); valproate inhibits CYP + raises lamotrigine
Monitoring & kinetics
Valproate: LFTs + pregnancy prevention; phenytoin: levels; lamotrigine: rash
Oral maintenance; IV for status. Never stop abruptly.
Source: NICE NG217 — Epilepsies · BNF — Antiepileptics