Tiagabine Monotherapy in the Treatment of Partial Epilepsy

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Abstract
Three studies were conducted to assess tiagabine (TGB) hydrochloride monotherapy in patients with partial seizures. The first was a double-blind, placebo-controlled trial of 11 patients (seven TGB, four placebo) undergoing evaluation for epilepsy surgery. Baseline antiepileptic drug (AED) therapy was discontinued abruptly before monotherapy. Although 24-h seizure rates increased during monotherapy in both groups, patients receiving TGB experienced fewer seizures than placebo patients. Subsequent studies (an open-label, dose-ranging study; n=31 and a double-blind, randomized comparison of 6 and 36 mg/day TGB; n=102 and 96, respectively) involved discontinuation of baseline AEDs. In the dose-ranging study, 19 of 31 patients (61%) converted to TGB monotherapy, with a mean final dose of 38.4 mg/day (range 24-54 mg/day) in those who completed the study (n=12). In the low-vs. high-dosage study, median 4-week complex partial seizure rates decreased significantly in patients from both dose groups who completed the monotherapy period (p<0.05 compared with baseline). In the intent-to-treat analysis, significantly more patients in the high-dose group experienced a reduction in seizures of at least 50% compared with the low-dose group (p = 0.038). Overall, the types of adverse events with TGB monotherapy were similar to those observed in add-on trials. These initial trials in difficult-to-treat epilepsy patients indicate that TGB monotherapy may provide a new approach to the treatment of patients with partial seizures refractory to other AEDs.