Comparative pharmacokinetics and bioavailability of two tylosin formulations in chickens after oral administration

Abstract

The pharmacokinetics and oral bioavailability of two tylosin formulations was carried out in broiler chickens according to a single dose, randomized, parallel design. The two formulations of tylosin (Tylosina® and Tylan®) were given orally at a dose level of 25 mg/kg b.w. after an overnight fasting (n=15 chicken/group). To calculate tylosin bioavailability, fifteen more chickens was assigned as group 3 and was given a single intravenous dose of tylosin (25 mg/kg b.w.). Serial blood samples were collected at different time points up to 24 hour post-drug  administration. A high performance liquid chromatography (HPLC) method was used for the determination of tylosin concentrations in chicken plasma. The pharmacokinetics analysis of the data was performed using non-compartmental analysis based on statistical moment theory with the help of commercially available software (WinNonlin®, Pharsight Corporation, Cary, NC, USA). There were no significant differences in the Cmax (3.05±0.63, 2.63±0.74 μg/ml), tmax (2.36±0.42, 2.30±0.38 h), t1/2β (1.99±0.38, 2.67±0.60 h), AUC0-12h (6.11±0.97, 5.37±1.16 μg.h/ml), AUC0-∞ (6.38±0.94, 5.57±1.15 μg.h/ml), MRT (3.53±0.24, 3.67±0.32 h), ClB/F (90.59±13.81,  169.38±54.44 ml/min/kg) and Vdz/F (16.85±4.74, 43.96±18.24 l/kg) between Tylosina® and Tylan®, respectively. The calculated oral bioavailability (F) for Tylosina® and Tylan® were 40.56 and 35.41%, respectively. Moreover, the relative bioavailability of  Tylosina® was 113.9% when compared to Tylan®. In conclusion, Tylosina® is comparable to Tylan® and both formulations can be used for treatment of susceptible microorganisms in veterinary medicine practice at a dose level of 25 mg/kg b.w.