Suvorexant, sold under the trade name Belsomra, is a medication for the treatment of insomnia. It is effective for insomnia, at least for four weeks and as compared to a placebo.  

  Suvorexant is a selective, dual orexin receptor antagonist (DORA) made by Merck & Co. It was approved for sale by the U.S. Food and Drug Administration (FDA) on August 13, 2014.The U.S. Drug Enforcement Administration (DEA) has placed it on the list of schedule IV controlled substances,]as it may lead to limited physical dependence or psychological dependence relative to the drugs or other substances in schedule III. The potential for psychological dependence is similar to that of zolpidem.  

  The drug was initially released November 2014 in Japan, then later reached the United States in February 2015and Australia in November 2016.

Medical uses  

  Suvorexant is used for the treatment of insomnia, characterized by difficulties with sleep onset and/or sleep maintenance.  

  It is unclear how the medication compares to others used for insomnia as no comparisons have been done.It is also unclear if this medication is safe among people with a history of addiction, as they were excluded from the clinical trials of suvorexant.

Contraindications  

  This drug is not recommended in people with liver impairment.Suvorexant pregnancycategory is currently classified as Category C. Based on animal testing, this medication may cause fetal harm during pregnancy and should only be given in pregnancy if the potential benefit justifies the potential harm to the fetus. Evidence is inconclusive about whether using this medication while breastfeeding puts the infant at risk of harm.  

  Suvorexant is contraindicated in people diagnosed with narcolepsy.

Mechanism of action

  Suvorexant exerts its therapeutic effect in insomnia 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 orexin receptor type 1 (OX1) and orexin receptor type 2 (OX2) is thought to suppress wake drive.Animal studies report the binding affinities for OX1 (0.55 nM) and OX2 (0.35 nM).

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