Gamma-hydroxybutyrate (GHB) for narcolepsy in adults: an updated systematic review and meta-analysis

Background: Narcolepsy is a chronic and debilitating sleep disorder characterized by cataplexy and excessive daytime sleeping. Gamma-hydroxybutyrate (GHB) has been widely used to treat narcolepsy, and new findings have been published in recent years. Objective: A meta-analysis was conducted to assess the efficacy and tolerability of GHB treatment in adults with narcolepsy. Methods: A systematic search of PubMed, Cochrane, Embase, Web of Science, and clinical-trials.gov from inception to June 2018 was performed. Change in daily diaries and polysomnographic data of narcoleptic patients were defined as the efficacy outcomes. The tolerability and acceptability outcomes were the rates of adverse events and dropping out for adverse effects or other reasons. Results: Fifteen randomized controlled trials involving 2104 participants were identified. GHB was found to improve cataplexy attacks (P = 0.001), subjective daytime sleepiness (P < 0.0001), daytime sleep latency (P < 0.0001), inadvertent naps/sleep attacks (P < 0.00001), effective rates (Clinical Global Impression of change) (P < 0.00001), hypnagogic hallucinations (P = 0.004), sleep paralysis (P = 0.004), stage 1 sleep (P = 0.04), slow wave sleep (P = 0.003), REM sleep (P = 0.0006), sleep shifts (P = 0.005), nocturnal awakenings (P = 0.004), quality of nocturnal sleep (P < 0.00001), chin muscle activity, and quality of life, but had no effect on stage 2 sleep (P = 0.88). GHB was less well tolerated than placebo because of side effects that occurred in a dose-dependent fashion (RR = 6.08; 95% CI = 2.18 to 16.97; P = 0.0006). Conclusions: GHB was effective in improving narcolepsy-cataplexy and related symptoms in adults but was less well tolerated than placebo because of dose-dependent side effects. (C) 2019 Elsevier B.V. All rights reserved.