Pharmacokinetics of tilmicosin in healthy pigs and in pigs experimentally infected with Haemophilus parasuis

A comparative pharmacokinetic (PK) study of tilmicosin (TIL) was conducted in 6 crossbred healthy pigs and 6 crossbred pigs infected with ( .) following oral administration of a single 40 mg/kg dose. The infected model was established by intranasal inoculation and confirmed by clinical signs, blood biochemistry, and microscopic examinations. Plasma TIL concentrations were determined by a validated high-performance liquid chromatography method with ultraviolet detection at 285 nm. PK parameters were calculated by using WinNonlin software. After TIL administration, the main PK parameters of TIL in healthy and -infected pigs were as follows: Area under the concentration-time curve, maximal drug concentration, half-life of the absorption phase, half-life of the distribution phase, and half-life of the elimination phase were 34.86 ± 9.69 28.73 ± 6.18 μgㆍh/mL, 1.77 ± 0.33 1.67 ± 0.28 μg/mL, 2.27 ± 0.45 2.24 ± 0.44 h, 5.35 ± 1.40 4.61 ± 0.35 h, and 43.53 ± 8.17 42.05 ± 9.36 h, respectively. These results of this exploratory study suggest that there were no significant differences between the PK profiles of TIL in the healthy and -infected pigs.