Long-term safety and efficacy of daridorexant in Japanese patients with insomnia disorder.

Objective/background: The short-term efficacy and safety of daridorexant, a dual orexin receptor antagonist, has been demonstrated in Japanese patients with insomnia disorder. The objective of this study was to evaluate, in a non-overlapping patient population to the short-term study, the long-term safety and efficacy of daridorexant in Japanese patients with insomnia disorder.

Patients/methods: In this Phase 3 open-label study conducted in Japan, 154 patients with insomnia disorder were randomized to daridorexant 50 mg (n = 102) or 25 mg (n = 52) for 52 weeks. The primary objective was to assess the safety and tolerability of daridorexant for up to 1 year. Secondary exploratory objectives were to evaluate the long-term efficacy of daridorexant on subjective sleep parameters (total sleep time, latency to sleep onset and wake after sleep onset) and daytime functioning (Insomnia Daytime Symptoms and Impacts Questionnaire).

Results: The incidence of treatment-emergent adverse events (TEAEs) was 74 % and 58 % in the 50 mg and 25 mg groups respectively. No serious drug-related TEAEs were reported. Both doses improved next-morning sleepiness (Visual Analog Scale) throughout the study. Five adjudicated adverse events of special interest were reported; excessive daytime sleepiness (n = 1, 25 mg; n = 2, 50 mg), sleep paralysis (n = 1, 50 mg) and nightmare (n = 1, 25 mg). Improvements in sleep and daytime functioning were maintained from Week 2 (first assessment) through to Week 52 in both dose groups.

Conclusions: Up to 52-weeks, daridorexant was well tolerated with sustained improvement in sleep onset, sleep maintenance and daytime functioning, supporting its long-term use in Japanese patients with insomnia disorder.