Randomized Controlled Trial of Solriamfetol for Excessive Daytime Sleepiness in OSA: An Analysis of Subgroups Adherent or Nonadherent to OSA Treatment

Background: Solriamfetol, a dopamine-norepinephrine reuptake inhibitor, is approved in the United States to improve wakefulness in adults with excessive daytime sleepiness (EDS) associated with OSA (37.5-150 mg/d).

Research question: Does solriamfetol have differential effects on EDS based on adherence to primary OSA therapy and does solriamfetol affect primary OSA therapy use?

Study design and methods: Participants were randomized to 12 weeks of placebo or solriamfetol 37.5, 75, 150, or 300 mg/d (stratified by primary OSA therapy adherence). Coprimary end points were week 12 change from baseline in 40-min Maintenance of Wakefulness Test (MWT) and Epworth Sleepiness Scale (ESS) in the modified intention-to-treat population. Primary OSA therapy use (hours per night, % nights) and safety were evaluated.

Results: At baseline, 324 participants (70.6%) adhered to OSA therapy (positive airway pressure use ≥ 4 h/night on ≥ 70% nights, surgical intervention, or oral appliance use on ≥ 70% nights) and 135 participants (29.4%) did not adhere. Least squares (LS) mean differences from placebo in MWT sleep latency (minutes) in the 37.5-, 75-, 150-, and 300-mg/d groups among adherent participants were 4.8 (95% CI, 0.6-9.0), 8.4 (95% CI, 4.3-12.5), 10.2 (95% CI, 6.8-13.6), and 12.5 (95% CI, 9.0-15.9) and among nonadherent participants were 3.7 (95% CI, -2.0 to 9.4), 9.9 (95% CI, 4.4-15.4), 11.9 (95% CI, 7.5-16.3), and 13.5 (95% CI, 8.8-18.3). On ESS, LS mean differences from placebo in the 37.5-, 75-, 150-, and 300-mg/d groups among adherent participants were -2.4 (95% CI, -4.2 to -0.5), -1.3 (95% CI, -3.1 to 0.5), -4.2 (95% CI, -5.7 to -2.7), and -4.7 (95% CI, -6.1 to -3.2) and among nonadherent participants were -0.7 (95% CI, -3.5 to 2.1), -2.6 (95% CI, -5.4 to 0.1), -5.0 (95% CI, -7.2 to -2.9), and -4.6 (95% CI, -7.0 to -2.3). Common adverse events included headache, nausea, anxiety, decreased appetite, nasopharyngitis, and diarrhea. No clinically meaningful changes were seen in primary OSA therapy use with solriamfetol.

Interpretation: Solriamfetol improved EDS in OSA regardless of primary OSA therapy adherence. Primary OSA therapy use was unaffected with solriamfetol.

Trial registry: ClinicalTrials.gov; No.: NCT02348606; URL: www.clinicaltrials.gov; EU Clinical Trials Register; No.: EudraCT2014-005514-31; URL: www.clinicaltrialsregister.eu.