First Generation Anticonvulsants (Contraindicated in pregnancy - esp. valproate, carbamazepine) Valproate Indications: 1st line for long-term management of tonic-clonic seizures Focal (local) seizures Absence epilepsy Tx for established epilepsy Myoclonic seizures Migraine prophylaxis Mechanism of Action: Mediates ↓ GABA transaminase → ↑ GABA → ↓ neural excitability Modulates Na+ & Ca2+ channels Adverse Effects: GIT upset Tremors Alopecia Pancreatitis Weight gain Teratogenicity (esp. neural tube defects) Hepatotoxicity Rash Dizziness Sedation Ataxia Thrombocytopenia Agranulocytosis Interactions: CYP450 Carbamazepine Indications: 1st line for focal seizures 1st line for trigeminal neuralgia 2nd line for generalized tonic-clonic seizures Mechanism of Action: Inactivates Na+ channels Adverse Effects: GIT upset Rash Hyponatremia, hypo-hydration & edema DRESS syndrome Blood count abnormalities (e.g., agranulocytosis, aplastic anemia) Teratogenicity (1st trimester: cleft lip/palate, spina bifida) Folate depletion Diplopia Ataxia Hepatotoxicity Dizziness Sedation Steven-Johnson Syndrome Interactions: Strong CYP450 inducer