Orexin Receptor Antagonist

Aka: Orexin Receptor Antagonist, Suvorexant, Belsomra

1. Indications
   1. Insomnia
2. Preparations
   1. Suvorexant (Belsomra)
3. Mechanism
   1. FDA Schedule IV Agent (as with other Nonbenzodiazepine Sedative-Hypnotic agents)
   2. Orexin (hypocretin) is a neurotransmitter that promotes wakefulness (deficiency in Narcolepsy)
   3. Blocking orexin transiently allows for sleep
4. Efficacy
   1. Similar effectiveness to other standard agents used for Insomnia (e.g. Zolpidem)
   2. Compared with Placebo, patients on Belsomra fall asleep 5-10 min faster, and stay asleep 22 min longer
5. Adverse Effects
   1. Daytime Somnolence
   2. Leg weakness (transient, rare)
6. Drug Interactions
   1. Metabolized by CYP3A4
   2. Moderate CYP3A4 Inhibitors (e.g. Verapamil)
      1. Start Belsomra at low dose (e.g. 5 mg)
   3. Strong CYP3A4 Inhibitors (e.g. Clarithromycin, Itraconazole)
      1. Avoid Belsomra with strong CYP3A4 Inhibitors
7. Disadvantages
   1. Expensive ($300/month) agent
   2. No benefit over Zolpidem (Ambien) which is $10/month at generic pricing
8. Dosing
   1. Orexin 15-20 mg orally at bedtime
9. References
   1. (2015) Presc Lett 22(2):10