Efficacy and safety of gabapentin 1800 mg treatment for post-herpetic neuralgia: a meta-analysis of randomized controlled trials.

WHAT IS KNOWN AND OBJECTIVE: Gabapentin has been used for the management of post-herpetic neuralgia (PHN). However, inconsistent results have been reported. This meta-analysis was performed to assess the efficacy and safety of gabapentin 1800 mg/day in PHN patients by conducting a meta-analysis.

METHODS: Electronic databases were searched for relevant randomized controlled trials (RCTs) that compared gabapentin 1800 mg/day to placebo for PHN. The primary outcomes were reduction in 24-h average pain intensity scores, 50% and 30% pain intensity reduction and gabapentin-related side effects. The secondary outcomes were reduction in sleep rating scores and improvement in Patient Global Impression of Change (PGIC) or Clinician Global Impression of Change (CGIC).

RESULTS AND DISCUSSION: Six RCTs were included. Gabapentin 1800 mg/day reduced the 24-h average pain intensity scores [standard mean differences (SMD) -0·50; 95% confidence interval (CI) -0·88, -0·13; I(2)  = 86·3%] and average daily sleep rating scores [weighted mean differences (WMD) -0·71; 95% CI -1·11, -0·32; I(2)  = 0%]. Gabapentin treatment yielded an improvement in pain intensity (risk ratio (RR) 1·88; 95% CI 1·35, 2·29; I(2)  = 64·8%; for 50% reduction and RR 1·43; 95% CI 1·12, 1·83; I(2)  = 0% for 30% reduction, respectively), PGIC (RR 1·49; 95% CI 1·28, 1·74; I(2)  = 0%), and CGIC (RR 1·58; 95% CI 1·29, 1·92; I(2)  = 30·9%). However, gabapentin increased the somnolence (RR 2·03; 95% CI 1·39, 2·98; I(2)  = 2%), dizziness (RR 2·68; 95% CI 1·95, 3·69; I(2)  = 15%), peripheral oedema (RR 9·10; 95% CI 3·23, 25·60; I(2)  = 2%), total adverse effects (RR 1·28; 95% CI 1·16, 1·42; I(2)  = 0%) and withdrawal due to adverse events (RR 1·51; 95% CI 1·06, 2·16; I(2)  = 6%), but these adverse effects were often mild to moderate.

WHAT IS NEW AND CONCLUSION: Treatment with gabapentin 1800 mg/day yielded a significant reduction in PHN up to 14 weeks. Gabapentin 1800 mg appeared safe in treating PHN for up to 24 weeks.