Effects Of An Orexin Receptor Antagonist On Blood Pressure And Metabolic Parameters

To the Editor The National Health and Nutrition Examination Survey, 2005 to 2008, indicated an association between a combination of sleep problems and hypertension and also suggested the necessity of prospective studies to understand the complex interplay between them.1 The following prospective study showed that short sleep (total sleep duration < 6 hours) was independently associated with a higher risk of developing hypertension among middleaged and elderly Korean adults.2 A very recent metaanalysis revealed that poor sleep quality was significantly associated with a greater likelihood of hypertension (odds ratio, 1.48; P value = .01), suggesting a significant association between sleep quality and hypertension.3 Suvorexant, an orexin receptor antagonist, has been approved as a drug for the treatment of insomnia and widely used to date in Japan. The daily restingphase administration of suvorexant improved glucose metabolism in db/db mice, without affecting body weight, food intake, and insulin sensitivity,4 proposing a beneficial effect of suvorexant on metabolic parameters in animal models. However, effects of suvorexant on blood pressure and metabolic parameters in humans remain unknown. To understand effects of suvorexant on blood pressure and metabolic parameters, we compared blood pressure and metabolic parameters at baseline with values after the start of suvorexant. Briefly, we retrospectively picked up patients who had been prescribed suvorexant between September 2014 and May 2017 and whose blood pressure and metabolic parameters before and after taking suvorexant were measured. Comparison between values before and after the start of suvorexant was performed by using paired t test; correlation between changed values of each parameter was performed by using Spearman’s correlation, and P < .05 was considered to be statistically significant. This study was approved by the Institutional Ethics Committee in National Center for Global Health and Medicine and was also performed in accordance with the Declaration of Helsinki. During observation period, 88 patients (age, 59.0 ± 18.0 (mean ± SD) years; male/female, 34/54) were prescribed suvorexant. Changes in body weight and blood pressure are shown in Table 1. Body weight significantly increased at 10 months, and systolic and diastolic blood pressures significantly increased at 2 and 4 months after the start of suvorexant, respectively. Hemoglobin A1c (HbA1c) and lowdensity lipoprotein cholesterol (LDLC) significantly increased at 8 months and 1 month after the start of suvorexant, respectively (Table 2). Surprisingly, suvorexant significantly reduced highdensity lipoprotein cholesterol (HDLC) at 3, 4, 6, 8, and 9 months after its start. Furthermore, HDLC showed a decrease