-Original-

Usefulness of Gabapentin as an Alternative/Adjunct Therapy for Delirium: A Retrospective Observational Study

Kakusho Chigusa Nakajima-Ohyama^1,2,#, Yoshie Shizusawa^3,4,#, Shotaro Uchiyama¹, Yasuhiro Kishi¹ and Hitoshi Tanimukai⁵

¹Department of Neuropsychiatry, Nippon Medical School Musashi Kosugi Hospital, Kanagawa, Japan
²Department of Neuropsychiatry, Ikeda Municipal Hospital, Osaka, Japan
³Department of Palliative Medicine, Ikeda Municipal Hospital, Osaka, Japan
⁴Department of Palliative Medicine, Osaka Gyoumeikan Hospital, Osaka, Japan
⁵School of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
^#Contributed equally

Background: Antipsychotics are commonly used to treat delirium but can adversely affect the extrapyramidal and cardiac conduction systems. Antipsychotic use has also been reported to be associated with increased mortality in older adults. Therefore, alternative and adjunct medications for delirium are necessary. We retrospectively assessed the efficacy and safety of gabapentin (GBP) as an alternative and adjunct medication for delirium.
Methods: We retrospectively investigated the records of patients with delirium treated with GBP (71 patients; median age, 81 years; interquartile range, 76-87.5 years; 54.9% males) at a general hospital. We examined duration to delirium improvement, as assessed by the Intensive Care Delirium Screening Checklist (ICDSC) and DSM-5 criteria, as well as adverse events.
Results: The median (interquartile range) GBP dose was 200 mg (150-350 mg)/day. A total of 71.8% and 85.9% of the patients failed to meet the diagnostic criteria for delirium at 2 days and 5 days after initial administration, respectively (p<0.05). In subgroup analysis, patients with a history of epilepsy or cerebrovascular disease responded better to GBP than did those without such histories, suggesting that patients with abnormal/borderline neuronal activity respond to GBP even though they do not exhibit seizures. GBP did not induce extrapyramidal symptoms, cardiac conduction disturbances, hyperglycemia, or epilepsy but caused sleepiness and myoclonus.
Conclusions: GBP may improve delirium with fewer adverse effects and may be a safe alternative or adjunct treatment for delirium. Dosage adjustment may be necessary to prevent sleepiness.

J Nippon Med Sch 2024; 91: 233-240

Keywords
gabapentin, delirium

Correspondence to
Kakusho Chigusa Nakajima-Ohyama, MD, PhD, Senior assistant professor at the Department of Neuropsychiatry, Nippon Medical School Musashi Kosugi Hospital, 1-383 Kosugi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8533, Japan
kakusho-ohyama@nms.ac.jp, kakusho.ohyama@gmail.com

Received, July 16, 2023
Accepted, December 13, 2023