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The determination of the novel insomnia medication lemborexant using a validated liquid chromatography-tandem mass

Brian Waters¹, Masato Masuda², Aya Matsusue³

¹Department of Forensic Medicine, Faculty of Medicine, Fukuoka University, 7-45-1 Nanakuma, Jonan-ku, Fukuoka, Japan. bwaters@fukuoka-u.ac.jp.

Forensic Toxicology

|July 16, 2025

Abstract

Purpose:

This study aims to detail the identification, confirmation, and quantitation of lemborexant from clinical and postmortem specimens using a validated LC-MS/MS method. Additionally, it investigates the tissue distribution of lemborexant in several postmortem cases.

Methods:

Lemborexant was isolated from the plasma of hospital patients or the postmortem specimens of forensic autopsy cases. Extraction from 0.1 mL or 0.1 g of sample was achieved by a modified QuEChERS protocol. The analysis was performed by liquid chromatography-tandem mass spectroscopy (LC-MS/MS). The quantitation method was validated in whole blood using internationally accepted parameters based on ANSI/ASB Standard 036. A total of 8 clinical samples and 13 forensic autopsy cases were analyzed by the validated method.

Results:

In clinical cases, lemborexant concentrations in plasma ranged from 2.7 to 225 ng/mL. Lemborexant concentrations in the blood of forensic autopsy cases ranged from below the lower limit of quantitation (2 ng/mL) to 276 ng/mL. The highest postmortem concentrations were found in liver, adipose tissue, pancreas, and kidney. The method demonstrated high recovery rates and precision, with no significant matrix effects or interferences from other drugs.

Conclusions:

The validated LC-MS/MS method proved effective for detecting and quantifying lemborexant in both clinical and forensic autopsy samples. The study highlights the importance of monitoring lemborexant and other dual orexin receptor antagonists (DORAs) in forensic investigations to understand their pharmacokinetics and potential toxicological effects.

Keywords:

Dual orexin receptor antagonist (DORA)Forensic toxicology LC–MS/MS Lemborexant Tissue distribution

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