Clinical experience with topiramate dosing and serum levels in children 12years or under with epilepsy

Only a limited topiramate dosing range (5-9 mg/kg/day) is approved by the U .S. Food and Drug Administration (FDA). We reviewed our topiramate dosing ( mg/kg/d) and corresponding serum levels (mug/mL) (n = 77) in 41 children wh o were treated to clinical response or tolerability. The patients were divi ded into older (6-12 years [n = 21]) and younger (less than or equal to5 ye ars [n = 20]) groups. Topiramate was given as monotherapy (n = 9), with an enzyme-inducing antiepileptic drug (n = 16) (phenobarbital, phenytoin, or c arbamazepine), or as polytherapy (n = 17) (another antiepileptic drug). In the older children, there was a good dosage to serum level correspondence. However, younger children on topiramate monotherapy or co-therapy with an e nzyme-inducing antiepileptic drug had relatively lower serum levels, but th e serum level was increased if they were on polytherapy without an enzyme-i nducing drug. This study supports a wider dosing range (7-22 mg/kg/day) of topiramate and dosage escalation beyond the approved range. Serum levels ar e useful in guiding topiramate dosing, especially in young children.