Authors (including presenting author) :
Han TM (1)(2), Tang MHY (1)(2), Tong HF (1)(2), Cheung YT (1)(2), Tseung JSB (1)(2), Yip MK (1)(2), Ching CK (1)(2), Chong YK (1)(2)
Affiliation :
(1) Hospital Authority Toxicology Reference Laboratory, Hong Kong SAR, China, (2) Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong SAR, China
Keyword 1: :
Ketamine analogue
Keyword 2: :
Fluoro-2-oxo-phenylcyclohexylethylamine
Keyword 3: :
Fluorexetamine
Keyword 4: :
Drugs of abuse
Introduction :
Ketamine analogues are new psychoactive substances that share the arylcyclohexylamine backbone of ketamine and produce dissociative effects through antagonistic activity at the N-methyl-D-aspartate receptor. Ketamine and its analogues have plagued Hong Kong over the last two decades. Our laboratory has identified outbreaks of multiple ketamine analogues in Hong Kong, including 2-oxo-phenylcyclohexylethylamine in 2017, 2-fluorodeschloroketamine (2F-DCK) and deschloroketamine in 2019, and tiletamine in 2019 to 2022. We describe the local emergence of a new ketamine analogue, fluoro-2-oxo-phenylcyclohexylethylamine, also known as fluorexetamine (FXE) since 2023.
Objectives :
To report the local emergence of FXE, common clinical presentation, and the potential difficulties in its detection.
Methodology :
Urine samples were analyzed by liquid chromatography quadrupole time-of-flight (LC-QTOF). Data of samples tested positive for FXE between Jan 2023 and Jan 2024 were retrieved from Laboratory Information System for analysis.
Result & Outcome :
14 cases of FXE abuse were encountered between Jan 2023 and Jan 2024. Detection of FXE can be difficult since it does not cross-react with bedside ketamine immunoassay and shares common metabolites with 2F-DCK. This may lead to misidentification of FXE metabolites as 2F-DCK metabolites on routine toxicology testing. Clinically, FXE appears to possess similar toxicity to ketamine and 2F-DCK. Co-ingestion with other recreational drugs is common, often complicating the clinical presentation.
