title: Pharmacokinetics of ractopamine and its organ distribution in rats.
abstract: Ractopamine, a β-agonist, is used to increase the proportion of lean meat in livestock. However, due to potential cardiovascular risks, ractopamine has been banned for use in food-producing animals in many countries. Nevertheless, pharmacokinetic studies of ractopamine have not been completed. The aim of this study was to develop a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of ractopamine. This validated method was used to investigate the pharmacokinetics and organ distribution of ractopamine in rats. The validation results complied with the U.S. Food and Drug Administration's standards. The oral bioavailability of ractopamine was 2.99%. After intravenous administration, ractopamine concentrations varied as follows: kidney > lung > spleen > heart > liver > muscle > plasma > brain. Nonlinear pharmacokinetics and strong partitioning into tissues were observed after intravenous administration of ractopamine. These effects may be due to nonlinear elimination via the kidney.
authors.affiliation: Institute of Pharmacology, and ¶Institute of Traditional Medicine, National Yang-Ming University , Taipei, Taiwan.
authors.forename: Jing-Kai
authors.initials: JK
authors.lastname: Ho
authors.forename: Teh-Ia
authors.initials: TI
authors.lastname: Huo
authors.forename: Lie-Chwen
authors.initials: LC
authors.lastname: Lin
authors.forename: Tung-Hu
authors.initials: TH
authors.lastname: Tsai
mesh_terms: D000318:Adrenergic beta-Agonists / Q000493:pharmacokinetics*; D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D010627:Phenethylamines / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
chemical_list: D000318:Adrenergic beta-Agonists; D010627:Phenethylamines; C060897:ractopamine
keywords: HPLC-MS/MS; bioavailability; pharmacokinetics; ractopamine; tissue distribution