High-Resolution LC-MS Approach for In Vitro Metabolite Characterisation of Etonitazene in Camels for Enhanced Doping...

The misuse of synthetic opioids particularly those from the benzimidazole class such as etonitazene poses significant challenges for doping control in animal sports including camels racing. These substances are powerful psychoactive agents with a high potential for abuse. Therefore, it is essential to implement robust detection and monitoring strategies to ensure fair competition and protect animal welfare.

In vitro studies were conducted using camel liver homogenates to investigate the metabolism of etonitazene. Metabolites were extracted and analysed using a Thermo Fisher Orbitrap Exploris 120 LC-HRMS system, which provides high-resolution and accurate mass detection. Validation on critical parameters were performed using in-house developed methods while data processing and metabolite characterisation were performed using Compound Discoverer software.

Six Phase I metabolites of etonitazene have been identified elucidating the metabolic pathways in camels. The metabolism was mainly characterised by dealkylation and nitro reduction processes. These metabolites hold significant potential as biomarkers for the long-term detection of etonitazene for doping control applications in camels.

This study highlights the effectiveness of advanced high-resolution LC-MS techniques in identifying and characterising the in vitro metabolites of etonitazene in camels. Due to its high potency and potential for misuse in camel racing, the identified metabolites serve as a foundation for effective doping control strategies. These findings contribute to improving regulatory frameworks designed to protect animal welfare and maintain the integrity of the sport.