Pharmacokinetics, tissue residues, and ex vivo pharmacodynamics of tylosin against Mycoplasma anatis in ducks.

Abstract

The pharmacokinetics of tylosin were investigated in 3 groups of ducks (n=6). They received a single dose of tylosin (50mg/kg) by intravenous (IV), intramuscular (IM), and oral administrations, respectively. Plasma samples were collected at various time points to 24hr post-administration to evaluate tylosin concentration over time. Additionally, tylosin residues in tissues and its withdrawal time were assessed using 30 ducks which received tylosin orally (50mg/kg) once daily for 5 consecutive days. After IV administration, the volume of distribution, elimination half-life, area under the plasma concentration-time curve, and the total body clearance were 7.07±1.98L/kg, 2.04hr, 19.47µg hr/ml, and 2.82 Lhr-1 kg-1 , respectively. After IM and oral administrations, the maximum plasma concentrations were 3.70 and 2.75µg/ml achieved at 1 and 2hr, and the bioavailability was 93.95% and 75.77%, respectively. The calculated withdrawal periods of tylosin were 13, 8, and 5days for kidney, liver, and muscle, respectively. For the pharmacodynamic profile, the minimum inhibitory concentration for tylosin against M. anatis strain 1,340 was 1µg/ml. The calculated optimal oral dose of tylosin against M. anatis in ducks based on the ex vivo pharmacokinetic/pharmacodynamic modeling was 61mgkg-1 day-1 .