To evaluate the effects of solriamfetol on measures of functioning and work productivity in a subgroup of participants with narcolepsy in a long-term extension study.

Solriamfetol, a dopamine/norepinephrine reuptake inhibitor, is approved in the US to improve wakefulness in adults with excessive daytime sleepiness (EDS) associated with narcolepsy (approved dose range: 75-150 mg/d) or obstructive sleep apnea (OSA; approved dose range: 37.5-150 mg/d).

Participants with EDS associated with narcolepsy or OSA who completed previous solriamfetol studies were eligible. The long-term extension study included a 2-week titration followed by a maintenance phase of ≤50 weeks (stable doses of 75/150/300 mg). Assessments included Functional Outcomes of Sleep Questionnaire short version (FOSQ-10) and Work Productivity and Activity Impairment Questionnaire: Specific Health Problem (WPAI:SHP). Mean (standard deviation; SD) changes from baseline are summarized. Safety was assessed. Data are reported for participants with narcolepsy.

The safety population included 226 participants with narcolepsy. Increases (improvements) in mean FOSQ-10 total score from baseline (mean change [SD]: 3.7 [3.2]) were sustained for the duration of treatment with solriamfetol. On WPAI:SHP, mean % reduction (improvement) from baseline was -26.7% for % activity impairment outside of work, -29.5% for % impairment while working (presenteeism), and -29.5% for % overall work impairment due to the problem. Common adverse events (AEs; ≥5%) included headache, nausea, anxiety, nasopharyngitis, decreased appetite, insomnia, and dry mouth; 6 participants (2.7%) had ≥1 serious AE.

Solriamfetol demonstrated sustained improvements over approximately 1 year in measures of functioning and work productivity in participants with narcolepsy. Safety was similar to prior solriamfetol studies.