Suvorexant: a novel therapy for the treatment of insomnia.

Suvorexant is a pharmacologically novel dual antagonist of orexin receptors OX1R and OX2R, which has an effect that promotes sleep by reducing arousal and wakefulness. Its approval for the treatment of insomnia was based on three clinical trials that found it to be efficacious and relatively well tolerated. Somnolence, headache, and dry mouth are the most common side effects. Because suvorexant has unique effects on arousal systems and rapid eye movement (REM) sleep, it is contraindicated in patients with narcolepsy, and its use should be avoided or closely monitored in patients at risk for REM sleep behavior disorder, depression, or delirium.