A double-blind, placebo-controlled study demonstrates sodium oxybate is effective for the treatment of excessive daytime sleepiness in narcolepsy

Abstract

Study objective: Assess the efficacy of sodium oxybate for the treatment of narcolepsy with an emphasis on excessive daytime sleepiness.

Design: Eight-week, multicenter, double-blind, placebo-controlled trial.

Setting: Forty-two sleep clinics in the United States, Canada, and Europe.

Participants: Two hundred twenty-eight adults with narcolepsy with cataplexy.

Interventions: Patients were withdrawn from antidepressant treatment and then randomly assigned to receive 4.5 g, 6 g, or 9 g of sodium oxybate nightly or placebo for 8 weeks. Six-gram and 9-g doses were titrated in weekly 1.5-g increments. Patients who were receiving placebo underwent a mock dose-titration schedule. Stimulant use continued unchanged. Excessive daytime sleepiness was measured using the Epworth Sleepiness Scale and Maintenance of Wakefulness Test. The Clinical Global Impression of Change was used to measure changes in disease severity. Changes in narcolepsy symptoms and adverse events were recorded in daily diaries.

Results: After 8 weeks, patients treated with 9 g of sodium oxybate nightly displayed a significant median increase of > 10 minutes in the Maintenance of Wakefulness Test (p < .001). Patients displayed dose-related decreases in median Epworth Sleepiness Scale scores and frequency of weekly inadvertent naps, which were significant at the 6-g and 9-g doses (for each, p < .001). The improvements in excessive daytime sleepiness were incremental to those achieved by concomitant stimulants alone. Significant improvements in the Clinical Global Impression of Change were noted for each group treated with sodium oxybate (p < or = .001). Adverse events were consistent with the known safety profile of sodium oxybate.

Conclusions: When combined with its previously demonstrated anticataplectic effects, the results of the current study indicate sodium oxybate is the first drug to demonstrate efficacy for the 2 major symptoms of narcolepsy.