|Drug class||Dual orexin receptor antagonist (DORA)|
|Main uses||Trouble sleeping|
|Side effects||Sleepiness, headache, unusual dreams, cough, dry mouth|
|Typical dose||10 to 20 mg OD|
|Bioavailability||82% (at 10 mg)|
|Metabolism||hepatic, CYP3A, CYP2C19|
|Elimination half-life||~12 hours|
|Excretion||Feces (66%), urine (23%)|
|Chemical and physical data|
|Molar mass||450.93 g·mol−1|
|3D model (JSmol)|
Suvorexant, sold under the trade name Belsomra, is a medication used to treat trouble sleeping, including trouble falling asleep and staying asleep. It may be effective for at least a year. It is taken by mouth, half an hour before bed.
Common side effects include sleepiness, headache, unusual dreams, cough, and dry mouth. Other side effects include abuse, sleep paralysis, suicide, anxiety, and a decreased ability to drive. Safety in pregnancy and breastfeeding is unclear. It is a dual orexin receptor antagonist (DORA).
Suvorexant was approved for medical use in the United States in 2014, and Canada in 2018. In the United States it costs about 380 USD per month as of 2021. In the United States it is a Schedule IV controlled substance.
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.
It is generally started at a dose of 10 mg per day and may be increased to 20 mg per day.
Suvorexant is not recommended in people with liver impairment. Suvorexant pregnancy category is 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.
The most common complaint about the drug is from users who report that it did not help them to sleep. Some people reported that the drug caused a sleep disturbance such as a nightmare, sleep terror, or abnormal dream. Others reported that the drug caused them to be more awake.
According to the U.S. Drug Enforcement Administration (DEA), suvorexant produces similar reinforcing effects to those of zolpidem and thus may have a similar abuse liability. As such, suvorexant has been designated a schedule IV controlled substance in the U.S. under the Controlled Substances Act.
Suvorexant is not recommended if people are also taking medications that strongly inhibit the liver enzyme CYP3A like itraconazole, lopinavir/ritonavir, clarithromycin, ritonavir, ketoconazole, indinavir/ritonavir, or conivaptan. If suvorexant is used with a medication that moderately inhibits the liver enzyme CYP3A, like verapamil, erythromycin, diltiazem, or dronedarone, it is recommended that the dose of suvorexant be adjusted.
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).
The bioavailability of suvorexant is at 82%. It is highly protein-bound. Food delays the time to max concentration. The primary route of elimination is through the feces, with approximately 66% of radiolabeled dose recovered in the feces compared to 23% in the urine. The elimination half-life is reported to be 12 hours.
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