General Information

Belsomra (suvorexant) is an orexin receptor antagonist. The orexin neuropeptide signaling system is a central promoter of wakefulness. Blocking the orexin receptor suppresses wakefulness.

Belsomra is specifically indicated for the treatment of insomnia characterized by difficulties with sleep onset and/or sleep maintenance.

Belsomra is supplied as a tablet for oral administration. The recommended dose is 10 mg, taken no more than once per night and within 30 minutes of going to bed, with at least 7 hours remaining before the planned time of awakening. If the 10 mg dose is well-tolerated but not effective, the dose can be increased. The maximum recommended dose of Belsomra is 20 mg once daily.

Clinical Results

FDA Approval

The FDA approval of Belsomra was based on three clinical trials in patients with insomnia characterized by difficulties with sleep onset and sleep maintenance.

Two similarly designed, 3-month, randomized, double-blind, placebo-controlled, parallel-group studies were conducted (Study 1 and Study 2). In both studies, non-elderly (age 18-64) and elderly (age ≥ 65) patients were randomized separately. For the studies together, non-elderly adults were treated with Belsomra 20 mg or placebo. Elderly patients were treated with Belsomra 15 mg or placebo. In Study 1 and Study 2, Belsomra 15 mg or 20 mg was superior to placebo for sleep latency as assessed both objectively by polysomnography and subjectively by patient-estimated sleep latency. Belsomra 15 mg or 20 mg was also superior to placebo for sleep maintenance, as assessed both objectively by polysomnography and subjectively by patient-estimated total sleep time. The effects of Belsomra at night 1 (objective) and week 1 (subjective) were generally consistent with later time points.

In a 1-month crossover study (Study 3), non-elderly adults (age 18-64 years, mean age 44 years) were treated with placebo and Belsomra at a dose of 10 mg, 20 mg or up to 80 mg. Belsomra 10 mg and 20 mg were superior to placebo for sleep latency and sleep maintenance, as assessed objectively by polysomnography.

Mechanism of Action

Belsomra (suvorexant) a highly selective antagonist for orexin receptors OX1R and OX2R. The mechanism by which suvorexant exerts its therapeutic effect in insomnia is presumed to be through antagonism of orexin receptors. The orexin neuropeptide signaling system is a central promoter of wakefulness. Blocking the binding of wake-promoting neuropeptides orexin A and orexin B to receptors OX1R and OX2R is thought to suppress wake drive. Antagonism of orexin receptors may also underlie potential adverse effects such as signs of narcolepsy/cataplexy.