Clinical Psychopharmacology and Neuroscience 2019; 17(4): 547-550  
Effect of Suvorexant on Nocturnal Delirium in Elderly Patients with Alzheimer’s Disease: A Case-series Study
Tomoki Hanazawa1,2, Yoshito Kamijo1
1Emergency Medical Center and Poison Center, Saitama Medical University Hospital, Saitama, 2Department of General Medicine, Fujimi Hospital, Tokyo, Japan
Correspondence to: Tomoki Hanazawa
Emergency Medical Center and Poison Center, Saitama Medical University Hospital, 38 Morohongo, Moroyama, Iruma-gun, Saitama 350-0495, Japan
Received: April 11, 2018; Revised: May 8, 2018; Accepted: May 15, 2018; Published online: November 30, 2019.
© The Korean College of Neuropsychopharmacology. All rights reserved.

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Suvorexant, an orexin receptor antagonist used for insomnia, has been shown to have a preventive effect on delirium in a randomized placebo-controlled trial. However, its effectiveness in the management of nocturnal delirium has not yet been determined. Here we report four cases in which elderly patients with moderate to severe Alzheimer’s disease who developed nocturnal delirium were treated with suvorexant. In case 1, 15 mg suvorexant was initiated to manage nocturnal delirium refractory to antipsychotics, antidepressants, and a Japanese herbal medicine, resulting in immediate sleep improvement. However, treatment discontinuation led to recurrence of symptoms, which were reversed by recommencing suvorexant. In case 2, as antipsychotics used for the treatment of nocturnal delirium were ineffective, 15 mg suvorexant was administered. The patient achieved rapid improvement in sleep. In case 3, the use of atypical antipsychotics for the treatment of nocturnal delirium was contraindicated, as the patient had diabetes. Therefore, 15 mg suvorexant was administered following good outcomes in cases 1 and 2, resulting in immediate sleep improvement. Finally, in case 4, 15 mg suvorexant was used as an initial medication for nocturnal delirium, and the patient showed sleep improvement immediately. Elevated orexin levels in the cerebrospinal fluid are reportedly linked to sleep deterioration in patients with moderate to severe Alzheimer’s disease. The immediate and reproducible action and effectiveness of suvorexant observed in our patients suggest that enhanced cerebral orexin activity might be associated with sleep-wake cycle disturbances due to delirium in elderly patients with Alzheimer’s disease.
Keywords: Suvorexant; Orexins; Delirium; Alzheimer disease.

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