Effectiveness of topiramate in patients with epilepsy transitioning from carbamazepine or oxcarbazepine – results of an open-label, non-interventional trial

Objective: To explore seizure frequency and tolerability in patients with epilepsy treated with topiramate (TPM; Topamax®) transitioning from carbamazepine (CBZ) or oxcarbazepine (OXC). Methods: Multicenter open-label non-interventional trial (TOPMAT-EPY-405) prospectively following patients with epilepsy ≥12 years of age who were previously unsuccessfully treated with CBZ (72.1%) or OXC (27.9%) for 26 weeks after transitioning to TPM. A 12-week retrospective seizure frequency was used as baseline. Results: 140 patients (54% female; mean (±SD) age 47±18 years) were enrolled. 72.1% of patients had unsuccessfully been treated with CBZ and 27.9% with OXC. Mean (±SD) duration of epilepsy was 14.3±13.7 years and patients had had an average of 2.2 AEDs (range, 1–10) prior to observation. 84% had seizures during the 12-week retrospective baseline. Most frequent seizure types at baseline were generalized tonic-clonic (52%), complex partial (25%), and simple partial (16%). Main reasons for transition from CBZ/OXC to topiramate were insufficient efficacy (75%) and/or side effects (80%). Mean dose of CBZ at treatment initiation of TPM was 825mg±397mg/day and 1254±555mg/day with OXC. At endpoint, the median TPM dose was 100mg/day. 73% of patients received TPM monotherapy by the end of observation. Mean (±SD) seizure frequency decreased significantly from 6±21/month at baseline to 1.4±5/month during the observation period. The responder rate (≥50% seizure reduction) during the last 3 months of observation was 91%, and 62% of patients remained seizure-free during this period. 19% of patients discontinued TPM, in 12% due to an adverse event (AE), and in 3% due to insufficient efficacy. The only treatment-emergent adverse events reported in ≥5% were paraesthesia (9%) and weight decrease (8%). Conclusions: In patients previously unsuccessfully treated with CBZ or OXC, topiramate was well tolerated and associated with a substantial reduction in seizure frequency and a high seizure-free rate.