Impact of sodium oxybate, modafinil, and combination treatment on excessive daytime sleepiness in patients who have narcolepsy with or without cataplexy.

Effects of sodium oxybate (SXB) on patients with narcolepsy with cataplexy (NC) or without cataplexy (NWOC) have not been separately evaluated in clinical trials.

Retrospective analysis evaluated data from a phase 3, randomized, placebo-controlled trial of SXB, modafinil, and SXB + modafinil versus placebo in adult NC patients (n = 95) or NWOC patients (n = 127). NC patients were identified based on medical history, concomitant medications, and sleep-onset REM periods on nocturnal polysomnography. The studied outcomes were changes from baseline at eight weeks on the Epworth Sleepiness Scale (ESS), the Maintenance of Wakefulness Test (MWT), and the Clinical Global Impression of Change (CGI-C).

Among NC and NWOC patients, ESS improvement was significantly greater with SXB and SXB + modafinil versus placebo. In NC patients, mean MWT sleep latency was significantly increased with SXB + modafinil versus placebo. In NWOC patients, mean MWT sleep latency significantly increased in all groups versus placebo. Higher percentages of patients in the SXB and SXB + modafinil groups were "very much improved" or "much improved" on the CGI-C versus placebo in both NC and NWOC populations, although the difference did not reach statistical significance in the NWOC populations. Adverse events were consistent with previously-reported profiles for modafinil and SXB. Nausea was more common in the SXB and SXB + modafinil groups. Dizziness and tremor were more common in the SXB + modafinil group only.

SXB alone and in combination with modafinil improved subjective ratings of excessive sleepiness and an objective measure of the ability to stay awake to similar extents in NC patients and NWOC patients.