Stability of Suvorexant (Belsomra<sup>®</sup>) Tablets in One-Dose Package

Abstract

One-dose packaging improves the convenience of patients in drug therapy and is useful for securing medication adherence. As psychiatric patients take plural, sometimes many, drugs before bedtime, there are increasing demands for utilizing one-dose packaging in dispensing drugs for these patients. Suvorexant is a potent and selective antagonist against orexin 1 and 2 receptors and its use as an insomnia remedy is rising rapidly. On the package insert of suvorexant (Belsomra®) tablets, there is a description "Store in the press through package (PTP) until use to protect from light and moisture". So far, however, little information has been available about the correct storage conditions regarding the one-dose packaging of Belsomra® tablets. In this study, we investigated the stability of one-dose packaged Belsomra® tablets, which were preserved for 30 days at room temperature or at room temperature under 85％ relative high humidity (high humidity), with a focus on the changes in appearance, hardness, mass, disintegration, content, and dissolution. Suvorexant content and the appearance of one-dose packaged Belsomra® tablets did not change even after 30 days. However, the tablets greatly lost hardness and showed an increase in mass, possibly due to the hygroscopicity of this formulation. These changes resulted in the prolonged disintegration time of one-dose packaged Belsomra® tablets and in the retarded dissolution of suvorexant from the tablets. These results suggest that Belsomra® tablets are hygroscopic and less stable. It is, therefore, desirable to avoid long-term, one-dose packaging of this formulation.