Assessment of switching to suvorexant versus the use of add-on suvorexant in combination with benzodiazepine receptor agonists in insomnia patients: A retrospective study
Masakazu Hatano 1, 2, 3, Hiroyuki Kamei 3*, Risa Inagaki 2, Haruna Matsuzaki 2, Manako Hanya 3, Shigeki Yamada 2, Nakao Iwata 1
1Department of Psychiatry, Fujita Health University School of Medicine, Aichi, Japan, 2Department of Clinical Pharmacy, Fujita Health University School of Medicine, Aichi, Nagoya, Japan, 3Office of Clinical Pharmacy Practice and Health Care Management, Faculty of Pharmacy, Meijo University, Nagoya, Japan
Received: February 17, 2017; Revised: April 5, 2017; Accepted: April 7, 2017; Published online: April 7, 2017.
© The Korean College of Neuropsychopharmacology. All rights reserved.

Objective Suvorexant is a novel hypnotic drug that does not interact with the conventional γ-aminobutyric acid (GABA)-A receptor. We investigated the method by which suvorexant was introduced in insomnia patients who were taking benzodiazepine receptor agonists (BzRA).
Methods This was a retrospective study. We extracted clinical data for patients who were prescribed suvorexant and were already using BzRA. The patients were assigned to two groups, the switching and add-on groups. We assessed the suvorexant discontinuation rate at one month after the prescription of the drug.
Results 119 patients were assigned to the switching group, and 109 were assigned to the add-on group. The add-on group exhibited a significantly higher all-cause discontinuation rate than the switching group (odds ratio: 2.7, 95% confidence interval: 1.5 to 5.0, adjusted P <0.001). Intolerability was a significantly stronger risk factor for suvorexant discontinuation in the add-on group (22.0% vs. 7.6%, P <0.002), and the most common adverse effect was oversedation.
Conclusion Our results show that the add-on of suvorexant increases the frequency of oversedation compared with switching in insomnia patients that are taking BzRA. However, this was only a preliminary retrospective study, and further studies will be required to confirm our findings.
Keywords: Suvorexant, Orexin receptor antagonists, Benzodiazepines, Insomnia, Adverse effects