Determination of the Metabolites and Metabolic Pathways for Three β-Receptor Agonists in Rats Based on LC-MS/MS

SIMPLE SUMMARY: Although β-receptor agonists are tightly controlled, there is still abuse. A general high-performance liquid chromatography-tandem mass spectrometry detection method was developed to measure three typical β-receptor agonists; the metabolites and metabolic pathways of SAL, CLB, and RAC in rats were investigated. The results showed that the metabolites in the rats mainly existed in the form of the prototype drugs and that they still had a few metabolites. The absorption and metabolism of the different β-receptor agonists in the rats were quite different, and the absorption and metabolism of the same β-receptor agonists in different tissues were also different. This will help to modulate the receptor agonist and to study its detection and metabolism in other species. ABSTRACT: This paper developed a universal detection method by high-performance liquid chromatography-tandem mass spectrometry to detect three typical clenbuterols, CLB, SAL, and RAC, and to investigate the metabolism of β-agonists in vivo. The parent ions and daughter ions of the three β-receptor agonist standards and the residues in the muscle, liver, and blood samples of rats were obtained by Total Ions Scan mode. The metabolites produced in different tissues at a specific time were qualitatively and quantitatively analyzed, and the corresponding metabolic pathways were inferred. The results showed that the three β-receptor agonists mainly existed in the form of prototype drugs in rats, with a small amount of clenbuterol methyl compound and albuterol methyl compound. There were significant differences in residual metabolism between different tissues of the same species. In addition, different β-receptor agonists have different absorption and utilization rates in rats.