INTRODUCTION: Excessive sleepiness (ES) is a prominent symptom of narcolepsy and obstructive sleep apnea (OSA). Solriamfetol, a selective dopamine/norepinephrine reuptake inhibitor, was effective in treating ES in narcolepsy and OSA in phase 3 studies. This study evaluated the long-term safety and efficacy of solriamfetol.
METHODS: Participants who completed prior solriamfetol studies initiated with a 2-week Titration phase followed by a Maintenance phase of ≤50 weeks. A 2-week placebo-controlled Randomized Withdrawal (RW) phase was conducted after 6 months. Change from beginning to end of RW in Epworth Sleepiness Scale (ESS) was the primary endpoint; Patient and Clinician Global Impression of Change (PGI-C and CGI-C, respectively) were secondary endpoints.
RESULTS: The safety population comprised 643 participants (226 narcolepsy; 417 OSA); 280 participants (141 placebo; 139 solriamfetol) completed the RW phase. At 6 months, ESS scores increased by 5.3 (least squares [LS] mean) versus 1.6 in the RW phase in participants randomized to placebo or solriamfetol, respectively (P<0.0001). For both secondary endpoints, greater percentages of participants randomized to placebo were reported as worse at the end of the RW phase versus solriamfetol (both P<0.0001). Maintenance of efficacy up to 1 year was also demonstrated across these endpoints. The most frequent adverse events (AEs; ≥5%) were headache, nausea, nasopharyngitis, insomnia, dry mouth, anxiety, decreased appetite, and upper respiratory tract infection; 27 (4.2%) participants had a serious AE.
CONCLUSION: These results demonstrate long-term efficacy of solriamfetol in participants with narcolepsy or OSA. The safety profile following chronic administration was consistent with prior studies of solriamfetol.