Conversion from valproic acid onto topiramate in adolescents and adults with epilepsy

OBJECTIVE: To explore efficacy and tolerability outcomes of topiramate (TPM) in patients with epilepsy transitioning from valproic acid (VPA) because of insufficient efficacy and/or tolerability onto TPM. METHODS: Multicenter, open label, single arm, non-interventional study examining patients (> or =12 years) with epilepsy, transitioning onto TPM from baseline mono-or combination therapy with VPA. TPM was added onto the existing antiepileptic drug (AED) treatment and started at a dose of 25 mg once daily. The dose was titrated up with 25 mg/day increments, once every 1-2 weeks, until a final dose between 50-200 mg/day was reached. Based on clinical judgment, the treating physician decided whether or not and when the existing AED treatment especially with VPA could be withdrawn. Documented were type and frequency of seizures, TPM dose, quality of life (QOLIE-10 questionnaire), subjective perception of improvement, and adverse events (AE). RESULTS: One hundred and forty-seven patients (59% women, mean age 41 years) switched from baseline VPA treatment onto TPM because of insufficient efficacy (61%) and/or poor tolerability (81%). Average duration of follow-up was 20.3 weeks with an overall discontinuation rate of 16.3% of patients, mainly because of AE (in 8.2% of 147 patients). At study endpoint, the intended shift to TPM monotherapy was achieved in 70% of patients at a median dose of 150 mg/day. A seizure reduction of > or =50% was achieved in 75% of patients in the last scheduled period (week 8-20), and 51% of patients entering that period remained seizure-free. Quality of life improved significantly as compared with baseline for all domains of QOLIE-10 (P < 0.001). Most frequent AEs were weight decrease (4.8%), paraesthesia and fatigue (4.1% each), speech disorder and headaches (2.7% each). CONCLUSIONS: In patients with epilepsy not satisfactorily treated with VPA, conversion to TPM was associated with improved seizure control as well as improvement in several aspects of quality of life.