Suvorexant (Belsomra) is the first orexin receptor antagonist to be approved for the treatment of insomnia-trouble falling or staying asleep (or both). Orexins are neuropeptides. They are central promoters of wakefulness. Blocking the orexin receptors suppresses the wake drive, and sleep occurs. In clinical trials suvorexant was found to be more effective than placebo in treating insomnia. The drug was not compared with other insomnia drugs. Suvorexant produces central nervous system (CNS) depression.

The recommended dose is 10 mg, but the dose can be increased if 10 mg is ineffective; patients shouldn't take more than 20 mg per day. The most common adverse effect is daytime somnolence. The performance of complex activities during sleep, such as driving, having sex, making phone calls, and preparing and eating food, can occur with any pharmaceutical sleep aid, including suvorexant. Doses greater than 10 mg increase the risk of such behaviors. As with other sleep aids (and other CNS depressants), suvorexant can produce or worsen depression or suicidal thoughts; in addition to daytime somnolence, it can also cause compromised respiratory function, sleep paralysis, hypnagogic or hypnopompic hallucinations (visual, tactile, auditory, or other sensory events that occur during the transition to a sleeping state [hypnagogia] or waking state [hypnopompia]), and cataplexy-like symptoms (a sudden loss of muscle tone).

Levels of suvorexant remain higher in women than in men and higher in obese patients than in nonobese patients, placing these patients at higher risk for adverse effects. Suvorexant is highly metabolized by an isoenzyme in the cytochrome P-450 (CYP) enzyme system, CYP3A, and interactions are possible with drugs that either inhibit or induce CYP3A. Strong CYP3A inhibitors (such as ketoconazole, clarithromycin, and ritonavir and other protease inhibitors) shouldn't be coadministered with suvorexant; they will increase circulating levels of suvorexant because the drug isn't metabolized as rapidly. Patients taking moderate inhibitors (such as ciprofloxacin, erythromycin, verapamil, and grapefruit juice) should be given a lower dose, 5 mg, initially; 10 mg may be used if 5 mg isn't effective. Drugs that are strong inducers of CYP3A (such as carbamazepine and phenytoin) can decrease the effectiveness of suvorexant because they will increase metabolism of the drug.

Nurses should take a thorough drug history when patients are prescribed suvorexant to treat insomnia, in order to identify potential drug interactions through the CYP3A isoenzyme. Nurses should instruct patients to avoid using alcohol or other CNS depressants while taking suvorexant to prevent excessive CNS depression. Patients and their families should be aware of the risks of sleep walking and engaging in other complex activities while not completely awake (patients may be at increased risk for date rape, for example, according to some reports). The prescriber should be notified if such behaviors occur. Nurses should also instruct patients to take suvorexant 30 minutes before the desired time of sleep and to take it only if it's at least seven hours before the time the patient needs to be awake. Because of the risk of daytime sedation, especially with higher doses of suvorexant, patients should be warned not to drive or operate heavy equipment the morning after taking suvorexant or if less than eight hours has passed since the time suvorexant was taken.

Complete FDA prescribing information can be found at http://1.usa.gov/1tqhmFG.