Comparative pharmacokinetics and bioavailability of tylosin tartrate and tylosin phosphate after a single oral and i.v. administration in chickens.

The pharmacokinetics and oral bioavailability of tylosin tartrate and tylosin phosphate were carried out in broiler chickens according to a principle of single dose, random, parallel design. The two formulations of tylosin were given orally and intravenously at a dose level of 10 mg/kg b.w to chicken after an overnight fasting (n = 10 chickens/group). Serial blood samples were collected at different time points up to 24 h postdrug administration. A high performance liquid chromatography method was used for the determination of tylosin concentrations in chicken plasma. The tylosin plasma concentration's time plot of each chicken was analyzed by the 3P97 software. The pharmacokinetics of tylosin was best described by a one-compartmental open model 1st absorption after oral administration. After intravenous administration the pharmacokinetics of tylosin was best described by a two-compartmental open model, and there were no significant differences between tylosin tartrate and tylosin phosphate. After oral administration, there were significant differences in the Cmax (0.18 ± 0.01, 0.44 ± 0.09) and AUC (0.82 ± 0.05, 1.57 ± 0.25)between tylosin phosphate and tylosin tartrate. The calculated oral bioavailability (F) of tylosin tartrate and tylosin phosphate were 25.78% and 13.73%, respectively. Above all, we can reasonably conclude that, the absorption of tylosin tartrate is better than tylosin phosphate after oral administration.