Metabolism and elimination of the catechol‐ o ‐methyltransferase inhibitor tolcapone in the horse

Metabolomics is a multidisciplinary field providing workflows for complementary approaches to conventional analytical determinations. It allows for the study of metabolically related groups of compounds or even the study of novel pathways within the biological system. The procedural stages of metabolomics; experimental design, sample preparation, analytical determinations, data processing and statistical analysis, compound identification and validation strategies are explored in this review. The selected approach will depend on the type of study being conducted. Experimental design influences the whole metabolomics workflow and thus needs to be properly assessed to ensure sufficient sample size, minimal introduced and biological variation and appropriate statistical power. Sample preparation needs to be simple, yet potentially global in order to detect as many compounds as possible. Analytical determinations need to be optimised either for the list of targeted compounds or a universal approach. Data processing and statistical analysis approaches vary widely and need to be better harmonised for review and interpretation. This includes validation strategies that are currently deficient in many presented workflows. Common compound identification approaches have been explored in this review. Metabolomics applications are discussed for clinical and forensic toxicology, human and equine sports anti‐doping and veterinary residues.

Section: Applicationsmentioning

confidence: 76%

Section: Equine Anti-dopingmentioning

confidence: 99%

Section: Equine Anti-dopingmentioning

confidence: 99%

Section: Applicationsmentioning

confidence: 99%

See 2 more Smart Citations

Metabolomics in clinical and forensic toxicology, sports anti‐doping and veterinary residues

Keen

Cawley

Reedy

et al. 2022

“…T A B L E 1 Proposed nitecapone metabolites detected during LC-MS screening of hydrolysed urine and plasma F I G U R E 4 Bar chart (annotated with the maximum peak area) showing the most abundance metabolites that were detected in postadministration urine pattern observed following both tolcapone 11,12 and entacapone administration. 7 Unlike nitecapone, metabolites with a reduced pentane-2,4-dione side chain (e.g.…”

Section: Resultsmentioning

confidence: 99%

The equine metabolism of the catechol‐O‐methyltransferase enzyme inhibitor nitecapone

Stanley

Deng²,

Berg³

et al. 2021

Self Cite

The abuse of performance-enhancing catecholamine-based stimulants, such as levodopa, is controlled in horse racing through the application of a regulatory threshold for the common major metabolite. However, catechol-O-methyltransferase (COMT) enzyme inhibitors can be used to restrict the catalysis of the stimulant, and so the concurrent administration of both substances would be a viable strategy to enhance racing performance while removing the risk of exceeding the threshold. A 200 mg dose of nitecapone, a COMT inhibitor, was administered to a Thoroughbred horse, and we have analysed the blood (≤24 h) and urine (≤48 h) samples that were collected. The extracts, analysed by UHPLC coupled to a high-resolution accurate mass spectrometer, were consistent with the presence of nitecapone glucuronide in all the samples collected. An in-depth examination of the samples was then carried out using targeted accurate mass extracted ion chromatograms to identify whether the metabolites that have been found in other species were also present in the extracts.Once these were tentatively identified, MS/MS experiments were conducted on some of the metabolites (M1-M5), as well as decomposition products (DP1 and DP2), to verify that spectrum included MS fragments were consistent with their proposed structures. The accumulated data provided evidence that is consistent with this drug having been converted into many metabolites and a few decomposition products. An unexpected finding was that O-methylation was a very minor pathway until after the reduction of the 2,4-pentanedione side chain had occurred.

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

Gray,

Lubbock,

Love

et al. 2024

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.