Intelligence benefit of the 3-methoxytyramine to tyramine ratio in equine urine

Analytical advances in horseracing medication and doping control from 2018 to 2023

The analytical approaches taken by laboratories to implement robust and efficient regulation of horseracing medication and doping control are complex and constantly evolving. Each laboratory's approach will be dictated by differences in regulatory, economic and scientific drivers specific to their local environment. However, in general, laboratories will all be undertaking developments and improvements to their screening strategies in order to meet new and emerging threats as well as provide improved service to their customers. In this paper, the published analytical advances in horseracing medication and doping control since the 22nd International Conference of Racing Analysts and Veterinarians will be reviewed. Due to the unprecedented impact of COVID-19 on the worldwide economy, the normal 2-year period of this review was extended to over 5 years. As such, there was considerable ground to cover, resulting in an increase in the number of relevant publications included from 107 to 307. Major trends in publications will be summarised and possible future directions highlighted. This will cover developments in the detection of 'small' and 'large' molecule drugs, sample preparation procedures and the use of alternative matrices, instrumental advances/applications, drug metabolism and pharmacokinetics, the detection and prevalence of 'endogenous' compounds and biomarker and OMICs approaches. Particular emphasis will be given to research into the potential threat of gene doping, which is a significant area of new and continued research for many laboratories. Furthermore, developments in analytical instrumentation relevant to equine medication and doping control will be discussed.

Intelligence-based anti-doping via an Intelligence and Drug Testing Management (IDTM) system

The Intelligence and Drug Testing Management (IDTM), a system that can enhance drug testing analytics with related horse information and intelligence in a single platform, can help identify and mitigate potential doping and other threats.

3-Methoxytyrosine as an indicator of dopaminergic manipulation in equine plasma

The use of catechol-O-methyltransferase inhibitors may mask doping agents, primarily levodopa, administered to racehorses and prolong the stimulating effects of dopaminergic compounds such as dopamine. It is known that 3-methoxytyramine is a metabolite of dopamine and 3-methoxytyrosine is a metabolite of levodopa thus these compounds are proposed to be potential biomarkers of interest. Previous research established a urinary threshold of 4,000 ng/mL for 3-methoxytyramine to monitor misuse of dopaminergic agents. However, there is no equivalent biomarker in plasma. To address this deficiency a rapid protein precipitation method was developed and validated to isolate target compounds from 100 µL equine plasma. A liquid chromatography-high resolution accurate mass (LC-HRAM) method using an IMTAKT Intrada amino acid column provided quantitative analysis of 3-methoxytyrosine (3-MTyr) with lower limit of quantification of 5 ng/mL. Reference population profiling (n = 1129) investigated the expected basal concentrations for raceday samples from equine athletes and showed a right-skewed distribution (skewness = 2.39, kurtosis = 10.65) which resulted from large variation (RSD = 71%) within the data. Logarithmic transformation of the data provided a normal distribution (skewness = 0.26, kurtosis = 3.23) resulting in the proposal of a conservative threshold for plasma 3-MTyr of 1,000 ng/mL at a 99.995% confidence level. A 12-horse administration study of Stalevo® (800 mg L-DOPA, 200 mg carbidopa, 1600 mg entacapone) revealed elevated 3-MTyr concentrations for 24-hours post-administration.