A Cochrane review [Abstract] 1 included 11 trials with a total of 2125 patients. All patients had drug-resistant partial epilepsy and were taking at least one monotherapy antiepileptic drug (AED). Gabapentin was compared to placebo (7 trials), to vigabatrin (one trial) and to lamotrigine (one trial). Two trials examined two different doses of gabapentin. The data from 6 trials (n=1206) were combined in meta-analyses. The overall risk ratio (RR) for at least 50% reduction in seizure frequency compared to placebo was 1.89 (95% CI 1.40 to 2.55). Dose regression analysis (for trials in adults) shows increasing efficacy with increasing dose, a dose of 1800 mg per day reduced seizure frequency by at least 50% in 25.3% of people (95% CI 19.3 to 32.3). The RR for treatment withdrawal compared to placebo was 1.05 (95% CI 0.74 to 1.49). Adverse effects were significantly associated with gabapentin compared to placebo. Risk ratios were as follows: ataxia 2.01 (99% CI 0.98 to 4.11), dizziness 2.43 (99% CI 1.44 to 4.12), fatigue 1.95 (99% CI 0.99 to 3.82) and somnolence 1.93 (99% CI 1.22 to 3.06). No significant differences were found for the adverse effects of headache (RR 0.79, 99% CI 0.46 to 1.35) or nausea (RR 0.95, 99% CI 0.52 to 1.73).
Comment: The quality of evidence is downgraded by indirectness (short follow-up time).
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