Wong Jenny K Y, Choi Timmy L S, Wong Celia O L, Curl Peter, Wan Terence S M, Ho Emmie N M
Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N.T., Hong Kong, China.
Department of Veterinary Regulation, Welfare and Biosecurity Policy, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N.T., Hong Kong, China.
Drug Test Anal. 2025 Aug;17(8):1380-1383. doi: 10.1002/dta.3844. Epub 2024 Dec 21.
Methylsulfonylmethane (MSM), also known as dimethyl sulfone, is a naturally occurring sulphur-containing compound that can be found in plants, animals and humans. MSM can also be a metabolite of dimethyl sulfoxide (DMSO). Due to their anti-inflammatory and analgesic effects, both MSM and DMSO are prohibited substances in horseracing. As both substances are naturally occurring, their misuse in horses is controlled by International Residue Limits (IRL) of 1200 and 15 μg/mL, respectively, in horse urine as established by the International Federation of Horseracing Authorities. The elimination of DMSO in horses has been reported; however, there has been no report on the elimination of MSM in horses. This paper describes a pilot study of an administration study of MSM in two geldings following one scoop (~15 g) of Pure MSM twice daily for six consecutive days. MSM in post-administration urine and blood samples was quantified by gas chromatography-mass spectrometry after sample dilution, with additional protein precipitation for the blood samples. The elimination profiles of MSM in urine and blood are described. The maximum detection time in urine at the IRL of 1200 μg/mL was around 4.5 days after the last dose. Plasma MSM in both horses was around 120 μg/mL at 4.4 days after the last dose, which was the last blood sample collected. As such, 120 μg/mL may indicate a possible IRL for controlling MSM in horse blood. The analysis of DMSO in post-MSM-administration samples showed that DMSO is not a significant metabolite of MSM in horses.
甲基磺酰甲烷（MSM），也称为二甲基砜，是一种天然存在的含硫化合物，可在植物、动物和人类中发现。MSM也可以是二甲基亚砜（DMSO）的代谢产物。由于它们的抗炎和镇痛作用，MSM和DMSO在赛马中都是违禁物质。由于这两种物质都是天然存在的，它们在马匹中的滥用由国际赛马管理机构联合会规定的马尿中分别为1200和15μg/mL的国际残留限量（IRL）来控制。已有关于马匹中DMSO消除的报道；然而，尚无关于马匹中MSM消除的报道。本文描述了一项对两匹 geldings 进行的MSM给药研究的初步研究，连续六天每天两次一勺（约15 g）纯MSM。给药后的尿液和血液样本中的MSM在样品稀释后通过气相色谱-质谱法进行定量，血液样本还进行了额外的蛋白质沉淀。描述了MSM在尿液和血液中的消除情况。在最后一剂后约4.5天，尿液中IRL为1200μg/mL时的最大检测时间。在最后一剂后4.4天，两匹马的血浆MSM约为120μg/mL，这是采集的最后一份血液样本。因此，120μg/mL可能表明控制马血液中MSM的可能IRL。对MSM给药后样本中DMSO的分析表明，DMSO不是马匹中MSM的重要代谢产物。
