BRECKENRIDGE, COLO. – Topiramate monotherapy at a target dosage of 100 mg/day–substantially less than conventional dosing–is at least as effective as standard therapeutic doses of carbamazepine or valproate for newly diagnosed epilepsy regardless of seizure type, Jacci Bainbridge, Pharm.D., said at a conference on epilepsy syndromes sponsored by the University of Texas at San Antonio.
Moreover, for this purpose topiramate (Topamax) at 100 mg/day has markedly fewer side effects and costs less than the much more widely used 200 mg/day dosing–and with no significant drop-off in efficacy, added Dr. Bainbridge of the University of Colorado, Denver.
She cited a study led by Michael D. Privitera, M.D., of the University of Cincinnati, who assigned 613 patients with newly diagnosed epilepsy to either carbamazepine (Tegretol) at 600 mg/day or valproate (Depakote) at 1,250 mg/day as preferred therapy based upon clinical presentation. Within each study arm, participants were then randomized to double-blind treatment using the traditional antiepileptic drug or topiramate at 100 or 200 mg/day.
Outcome measures included time to first seizure, time to withdrawal from the study, and the proportion of patients seizure free during the last 6 months of the trial, Dr. Bainbridge said.
In both study arms there were no significant differences in these efficacy measures between the various treatments. However, patients on topiramate at 100 mg/day had the lowest rate of study discontinuation due to adverse events (Acta Neurol. Scand. 2003;107:165–75).
In a more recent secondary post hoc analysis of data from the Johnson & Johnson-sponsored trial, it was determined that there were no significant differences in efficacy for the various drugs in patients with partial-onset seizures at baseline compared with those who had generalized seizures.