Tissue deposition and residue depletion of cyadox and its three major metabolites in pigs after oral administration.

Tissue deposition and residue depletion profiles of cyadox (Cyx) and its three major metabolites, including 1,4-bisdesoxycyadox (Cy1), 4-desoxycyadox (Cy2), and quinoxaline-2-carboxylic acid (QCA), in pigs after multiple oral administrations were determined. Thirty-five healthy adult pigs were randomly divided into seven groups and orally treated with Cyx at a dosage of 20 mg/kg of body weight for five consecutive days. Each group of five pigs was randomly slaughtered 12, 24, 72, 120, 168, 216, and 264 h after the last dosing, and tissue samples, including muscle, liver, kidney, and fat, were collected and analyzed via the liquid chromatography-tandem mass spectrometry method. The concentration-time data of Cyx and its three metabolites (Cy1, Cy2, and QCA) were analyzed with WinNonlin. Results showed that metabolites of Cyx were quickly generated in swine tissues and the concentrations of QCA in kidney were higher than those of Cyx and other metabolites in all edible tissues. These results provide further insight into the metabolism of Cyx and confirmation of the residue marker and target tissue of Cyx in pigs.