Use of in vitro technologies to study phase II conjugation in equine sports drug surveillance

Abstract

Background: Within equine drug surveillance, there is significant interest in analyzing intact phase II conjugates of drugs in urine, but progress has been limited by a lack of reference material. Method: In this study, in vitro techniques using equine liver fractions were employed to produce glucuronide and sulfate conjugates of stanozolol, 16β-hydroxystanozolol and nandrolone, the glucuronide conjugate of morphine and the glutathione metabolite of chlordinitrobenzene for the first time in equine sports drug surveillance. Results: The glucuronide conjugate of the synthetic progestagen altrenogest was also produced in vitro, removing the requirement for sample hydrolysis during routine urinalyses. Conclusion: These results highlight the potential of in vitro studies for the production of phase II reference material, allowing the development of assays based on intact conjugates.