Background: Epilepsy is a common neurologic disorder, affecting approximately 50 million people worldwide; nearly a third of these people are not well controlled by a single antiepileptic drug and usually require treatment with a combination of two or more antiepileptic drugs. In recent years, many newer antiepileptic drugs have been investigated as add-on therapy for partial epilepsy; losigamone is one of these drugs and is the focus of this systematic review.
Objectives: To investigate the efficacy and safety of losigamone when used as an add-on therapy for partial epilepsy.
Search methods: We searched the Cochrane Epilepsy Group Specialized Register (1 May 2012), the Cochrane Central Register of Controlled Trials (CENTRAL Issue 4 of 12, The Cochrane Library, 2012) and MEDLINE (1 May 2012). We searched trials registers and contacted the manufacturer of losigamone and authors of included studies for additional information. There were no language restrictions.
Selection criteria: Randomized controlled add-on trials comparing losigamone with placebo for partial epilepsy.
Data collection and analysis: Two review authors independently assessed trial quality and extracted data. The primary outcomes were 50% or greater reduction in seizure frequency and seizure freedom; the secondary outcomes were treatment withdrawal and adverse events. Results are presented as risk ratios (RR) with 95% confidence intervals (CIs) or 99% CIs (for the individual listed adverse events to make an allowance for multiple testing).
Main results: Two trials involving a total of 467 patients were eligible for inclusion. Both trials assessed losigamone 1200 or 1500 mg/d as an add-on therapy for partial epilepsy. One trial was assessed as being of good methodologic quality while the other was of uncertain quality. For the efficacy outcomes, results did show patients taking losigamone were significantly more likely to achieve a 50% or greater reduction in seizure frequency (RR 1.75; 95% CI 1.14 to 2.72), but associated with a significant increase of treatment withdrawal when compared with those taking placebo (RR 2.16; 95% CI 1.28 to 3.67). For the safety outcomes, results indicated the proportion of patients who experienced adverse events in the losigamone group was higher than the placebo group (RR 1.34; 95% CI 1.00 to 1.80), dizziness was the only adverse event significantly in relation to losigamone (RR 3.82; 99% CI 1.69 to 8.64). The proportion of patients achieving seizure freedom was not reported in either trial report. A subgroup analysis according to different doses of losigamone showed that a higher dose of losigamone (1500 mg/d) is associated with a greater reduction in seizure frequency than lower doses, but is also associated with more dropouts due to adverse events.
Authors' conclusions: The results of this review showed losigamone can reduce seizure frequency but was associated with more treatment withdrawals when used as an add-on therapy for people with partial epilepsy. However, trials included were of short-term duration and uncertain quality. Future well-designed randomized, double-blind, placebo-controlled trials with a longer-term duration are needed.