Losigamone add-on therapy for partial epilepsy

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 (AED) and usually require treatment with a combination of two or more AEDs. In recent years, many newer AEDs have been investigated as add-on therapy for partial epilepsy; losigamone is one of these drugs and is the focus of this systematic review. This is an update of a Cochrane review first published in 2012 (Cochrane Database of Systematic Reviews 2012, Issue 6).

To investigate the efficacy and safety of losigamone when used as an add-on therapy for partial epilepsy.

We searched the Cochrane Epilepsy Group Specialized Register (16 February 2015), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 16 February 2015) and MEDLINE (Ovid, 1946 to 16 February 2015). We searched trials registers and contacted the manufacturer of losigamone and authors of included studies for additional information. We did not impose any language restrictions.

Randomized controlled, add-on trials comparing losigamone with placebo for partial epilepsy.

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 (RRs) with 95% confidence intervals (CIs) or 99% CIs (for the individual listed adverse events to make an allowance for multiple testing).

Two trials involving a total of 467 patients, aged over 18 years, were eligible for inclusion. Both trials assessed losigamone 1200 mg/day or 1500 mg/day as an add-on therapy for partial epilepsy. One trial was assessed as being of good methodological 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 1.76; 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 reported 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/day) was associated with a greater reduction in seizure frequency than lower doses, but was also associated with more dropouts due to adverse events.

The results of this review showed losigamone did 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. No new studies have been found since the last version of this review.