Abstracts

RATIONALE: Topiramate is approved for use in children greater than age 2 years. However, only a limited dosing range (5-9 mg/Kg/d) is approved. We review our experience with topiramate dosing and corresponding serum levels in children who were treated to clinical response or tolerability. METHODS: Topiramate dosing (mg/Kg) and serum levels (mgms/mL)(n = 67) were obtained from 40 children from the Epilepsy Clinic at the University of Texas - Houston. The patients were divided into older (12-6 years [n = 17]) and young children (5 years or less [n = 23]). Topiramate was given as monotherapy (MT; n = 8), as polytherapy (PT; n = 16)(valproate, felbatol, lamotrigine, or tiagabine), or with an enzyme-inducing antiepileptic drug (PT/EIAED; n = 16)(phenobarbital, phenytoin, or carbamazepine). RESULTS: In older children, there was a good dose-serum level correspondence. However, young children on topiramate MT or PT/EIAED had relatively lower serum levels but the serum level was increased if on PT (see Table). CONCLUSIONS: This study supports a wider dose range (2-35 mg/Kg/d) for topiramate dosing in children. Many children will benefit from dose escalation beyond the approved range. Serum levels are useful in guiding topiramate dosing, especially in young children who often require much higher daily doses.