Pharmacokinetics of Tilmicosin in Plasma, Urine and Feces after a Single Intragastric Administration in Donkey (Equus asinus)

Abstract

Background: Tilmicosin, a macrolide antibiotic, has the potential to treat bacterial respiratory infections in donkeys. However, the pharmacokinetics of tilmicosin in donkeys have not been reported. Objectives: The aim of this study was to investigate the pharmacokinetics of tilmicosin in donkey plasma, urine and feces after a single intragastric administration to determine the suitability of tilmicosin for donkeys. Animals: A total of 4 healthy fattening male donkeys were selected with body weights of 148, 140, 145, and 135 kg, with an average body weight of 142.00 ± 4.95 kg. Methods: The donkeys were administered intragastrically a single dose of 10 mg·kg-1 BW tilmicosin. Blood, urine and fecal samples were collected. The concentrations of tilmicosin in plasma, urine, and feces were determined using high-performance liquid chromatography-tandem masss pectrometry. Results: After a single intragastric administration of 10 mg·kg-1 body weight, tilmicosin in donkey plasma reached a maximum concentration of 11.23 ± 5.97 mg·L-1 at 0.81 ± 0.11 h, with a mean residence time of 8.05 ± 2.44 h, a Cl/F of 0.48±0.22 L·kg-1·h-1, and a Vd/F of 9.28 ± 4.10 L·kg-1. The percentage of tilmicosin excreted through the urine of donkeys is (2.47±0.43)%, and the percentage excreted through the feces is (66.43±8.65)%. Conclusions: A single intragastric administration of 10 mg·kg-1 BW of tilmicosin to donkeys was rapidly absorbed and was able to achieve plasma concentrations of against pathogenic bacteria.