Assessment of Switching to Suvorexant versus the Use of Add-on Suvorexant in Combination with Benzodiazepine Receptor Agonists in Insomnia Patients: A Retrospective Study

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: One hundred and nineteen 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.