Pharmacokinetics of tylvalosin in healthy and experimentally mycoplasma gallisepticum infected broiler chickens

A study of tylvalosin pharmacokinetics was conducted in healthy and Mycoplasma gallisepticum-infected broiler chickens. Tylvalosin was administered intravenously and orally at a dose rate of (25 mg/kg b.wt.) to determine its concentrations in blood as well as its kinetic disposition. The serum concentration time curve indicated a two compartment open model. Following intravenous injection, the mean elimination half-lives (t1/2) of (6.666±0.285 and 3.048±0.232 h) before and after infection, respectively. The apparent volume of distribution (Vd(area)) of tylvalosin was (3.802±0.148 and 0.657±0.367 L/Kg) with body clearance CLβ (0.953±0.040 and 1.976±o.743. L/kg/h) with mean of MRT was (9.314±0.407 and 1.739±0.779 h) in healthy and M. gallisepticum -infected chickens, respectively. Following oral administration, Tylvalosin was absorbed with (t1⁄2ka) of (0.963±0.045 and 0.958±0.207 h) with peak serum concentration of (1.226±0.041 and 0.0760±0.024 μg/ml) at (tmax) of (1.723±0.04 and 1.310±0.055 h) and eliminated with (t1⁄2β) of (3.504±0.49 and 3.862±0.103 h) in healthy and infected chickens. The systemic bioavailability of Tylvalosin (F%) following oral administration was (48.39±0.001 and 72.96±0.003 %) in healthy and infected birds respectively. It is to conclude that serum and tissues Tylvalosin concentration following twicedaily dose of (25 mg/Kg b. wt./day) were suitable to maintain its therapeutic regimen for treatment of mycoplasma infection in broiler chickens, in addition mycoplasma infection significantly decrease and/or consumed serum concentration, increased elimination rate so it is recommended that dose rate is adjusted in case of mycoplasma infection.