A look at the orexin receptor antagonism approach for the treatment of insomnia

This perspective review is aimed at examining the efficacy and tolerability of orexin receptor antagonists for the treatment of insomnia. Electronic searches of The Cochrane Central Register of Controlled Trials and the standard bibliographic databases PubMed, MEDLINE, EMBASE and PsycINFO were performed for randomized controlled trials evaluating orexin receptor antagonists for the treatment of insomnia. Data from 4 clinical trials of suvorexant has been included in this review. Suvorexant is the only orexin receptor antagonist that has been approved for the clinical treatment of insomnia. The duration of the included trials ranged from 4 weeks to over a year, while the drug doses of suvorexant ranged from 10 to 80 mg. Although suvorexant demonstrated improvement in sleep initiation and maintenance, at clinically used doses of approximately 20 mg, suvorexant was more beneficial for sleep maintenance. Suvorexant was reported to be generally well tolerated. Somnolence, excessive daytime sleepiness and fatigue were the most common adverse events. Other orexin receptor antagonists are currently in varying stages of investigation. Orexin receptor antagonists are a promising group of drugs for the treatment of insomnia.