Objective: To evaluate the relationship between baseline seizure frequency and stabilized topiramate dosage and the effect of individualized treatment on tolerability in adults with partial-onset seizures receiving other antiepileptic drugs (AEDs).
Methods: In this 20-week, open-label trial, dosages of medications were adjusted according to clinical response. Dosage and seizure response data were analyzed for 2 groups defined by baseline seizure frequency: <4 and >/=4 seizures per month.
Results: In the outcome evaluable population (n = 471), the mean +/- SEM stable topiramate dosage was 303 +/- 139 mg/d when baseline seizure frequency was <4 seizures/month and 341 +/- 153 mg/d when baseline seizure frequency was >/=4 seizures/month (p = 0.005). The most common adverse events were somnolence (8.5%), fatigue (7.3%), nausea (5.3%), and dizziness (5.0%). Cognitive complaints were reported by <3% of patients. When concomitant AED dosages were reduced, 14% of patients discontinued topiramate due to adverse events compared with 23% if the concomitant AED dosage was unchanged or increased.
Conclusions: When clinicians individualize topiramate dosage according to clinical response, the stabilized topiramate dosage as add-on therapy is influenced by baseline seizure frequency. Topiramate tolerability is improved when dosages of concomitant AEDs are reduced.