Hong Kong Med J 2024 Aug;30(4):337 | Epub 22 Jul 2024
© Hong Kong Academy of Medicine. CC BY-NC-ND 4.0
LETTER TO THE EDITOR
Another ketamine analogue on the horizon
TM Han, MB, ChB1,2; Magdalene HY Tang, PhD1,2; HF Tong, FHKCPath, FHKAM (Pathology)1,2; YT Cheung, MB, ChB1,2; Jeremiah SB Tseung, MB, ChB1,2; MK Yip, MB, BS1,2; CK Ching, FRCPA, FHKAM (Pathology)1,2; YK Chong, FHKCPath, FHKAM (Pathology)1,2
1 Hospital Authority Toxicology Reference Laboratory, Hong Kong SAR, China
2 Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong SAR, China
Corresponding author: Dr YK Chong (cyk280a@ha.org.hk)
Full paper in PDF
To the Editor—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.1
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 2-fluorodeschloroketamine (2F-DCK) and
deschloroketamine in 2019,3 and tiletamine in 2019
to 2022 (according to data on file in the Hospital
Authority Toxicology Reference Laboratory).
We report identification of a new ketamine
analogue, fluoro-2-oxo-phenylcyclohexylethylamine,
also known as fluorexetamine (FXE). Recreational use
of FXE was first reported in 2018.4 Our laboratory has
detected increasing use of FXE in Hong Kong since
mid-2023, with FXE now identified in urine samples
of 14 patients. 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 and co-ingestion
with other recreational drugs is common,
often complicating the clinical presentation.
Effective prevention of the emergence of new
psychoactive substances can be achieved through
prompt communication and accurate toxicology
testing. This approach has been successful in halting
the upward trajectory of various ketamine analogues.
When encountering patients with clinical features
of ketamine abuse but negative immunoassay or
urine toxicology results, clinicians are encouraged to
submit urine specimens to our laboratory for further
testing.
Author contributions
Concept or design: All authors.
Acquisition of data: All authors.
Analysis or interpretation of data: All authors.
Drafting of the manuscript: TM Han, YK Chong.
Critical revision of the manuscript for important intellectual content: All authors.
Acquisition of data: All authors.
Analysis or interpretation of data: All authors.
Drafting of the manuscript: TM Han, YK Chong.
Critical revision of the manuscript for important intellectual content: All authors.
All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.
Conflicts of interest
All authors have disclosed no conflicts of interest.
Funding/support
This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
References
1. Morris H, Wallach J. From PCP to MXE: a comprehensive
review of the non-medical use of dissociative drugs. Drug
Test Anal 2014;6:614-32. Crossref
2. Chong YK, Tang MH, Chan CL, Li YK, Ching CK, Mak
TW. 2-oxo-PCE: ketamine analogue on the streets. Hong
Kong Med J 2017;23:665-6. Crossref
3. Li C, Lai CK, Tang MH, Chan CC, Chong YK, Mak TW.
Ketamine analogues multiplying in Hong Kong. Hong
Kong Med J 2019;25:169. Crossref
4. National Drug Early Warning System. Alert from the NDEWS Web Monitoring Team: online mentions of fluorexetamine. 2022. Available from: https://ndews.org/wordpress/files/2023/04/8.12.22.pdf. Accessed 12 Jul 2024.