Preliminary open-label experience with topiramate in primary generalized seizures

Preliminary data concerning the effectiveness of topiramate (TPM) in the management of resistant primary generalized seizures were obtained from the open-label extension of a double-blind, placebo-controlled trial of TPM. The controlled trial enrolled patients experiencing three or more primary generalized tonic-clonic seizures (PGTCS) during an 8-week baseline period. Twelve of 13 patients who completed double-blind treatment elected to receive extended open therapy with TPM and were followed for periods ranging from 2 to 11 months. Of the 12 patients, 11 (92%) experienced a 50% or greater reduction in tonic-clonic seizures during their last 2 months of open-label TPM therapy compared to their pre-double-blind baseline period, and 7 (58%) were seizure-free during the open extension. Of five patients reporting absence seizures at baseline, four (80%) demonstrated a 50% or greater reduction in seizures. In seven of the 12 patients, a concomitant antiepileptic drug (AED) was discontinued or its dosage was reduced during open TPM treatment. The most common adverse events observed in the open study extension were weight reduction (five patients), weight increase (two patients), and drowsiness (two patients). The results of controlled trials are needed to determine the efficacy of TPM in primary generalized seizures. However, these preliminary findings are encouraging.