Oral Partial-Onset or Primary Generalized Tonic-Clonic Seizures Monotherapy <2 years: Safety and efficacy not established 2 to <10 years: 25 mg PO at night for 1 week; titrate dose over 5-7 weeks to target daily maintenance dose (weight based) and divide into q12hr dosing schedule Weight-based dosing Up to 11 kg: 150 mg/day minimum; 250 mg/day maximum 12-22 kg: 200 mg/day minimum; 300 mg/day maximum 23-31 kg: 200 mg/day minimum; 350 mg/day maximum 32-38 kg: 250 mg/day minimum; 350 mg/day maximum >38 kg: 250 mg/day minimum; 400 mg/day maximum >10 years 25 mg PO q12hr initially Titrate by increments of 50 mg/week up to 200 mg q12hr Adjunctive therapy <2 years: Safety and efficacy not established 2-16 years: 25 mg PO qHS(once at night) initially for first week (based on 1-3 mg/kg/day); increase dose by 1-3 mg/kg/day PO divided q12hr at 1-2 week intervals to 5-9 mg/kg/day divided q12hr >17 years: 25-50 mg/day PO initially; increase by 25-50 mg/day at weekly intervals to 100-200 mg q12hr for partial onset seizures and 200 mg q12hr for generalized tonic/clonic seizures Lennox-Gastaut Syndrome Adjunctive therapy <2 years: Safety and efficacy not established 2-16 years: 25 mg PO qHS initially for first week (based on 1-3 mg/kg/day); increase dose by 1-3 mg/kg/day PO divided q12hr at 1-2 week intervals to 5-9 mg/kg/day divided q12hr >17 years: 25-50 mg/day PO initially; increase by 25-50 mg/day at weekly intervals to 100-200 mg q12hr for partial onset seizures and 200 mg q12hr for generalized tonic/clonic seizures Migraine Headache Indicated for prophylaxis of migraine headache <12 years: Safety and efficacy not established Guide dose/titration rate by clinical outcome; if needed, use longer intervals between dose adjustments >12 years Titrate over 4 wk to achieve a dose of 50 mg PO BID Week 1: 25 mg PO qHS(once at night) Week 2: 25 mg PO BID Week 3: 25 mg PO in the morning and 50 mg HS Week 4: 50 mg PO BID