Abstract: The systemic bioavailability and lung tissue distribution of valnemulin were investigated in swine. About 65 pigs received 10 mg kg-1 body weight of valnemulin by either intravenous (i.v.) or oral (p.o.) route in two studies: study A (10 pigs, i.v. or p.o.) and study B (55 pigs, p.o.). The plasma and lung tissue concentration of the drug were determined by a validated HPLC-MS/MS method. Plasma concentration-time data after i.v. administration (10 mg kg-1 b.w.) were best described by a two-compartment open model. The pharmacokinetic parameters were elimination rate (ke) 0.95±0.17 h-1, the maximum concentrations 4.63±0.66 μg mL-1, area under the plasma concentration-time curve (AUCinf) 5.30±0.37 (h*μg) mL-1. On the other hand, A one-compartment model with a 1st order absorption rate was best fitted to the plasma concentration-time curve of valnemulin after oral administration (10 mg kg-1 b.w.) and the absorption rate (ka) was 0.34±0.03 h-1, the elimination rate (ke) was 1.05±0.19 h-1, the maximum concentration was 0.59±0.08 μg mL-1 at 1.98±0.21 h (tmax), the mean p.o. bioavailability (F) was 57.43%. Following p.o. administration, a mean valnemulin concentration of 0.14 μg g-1 was detected in lung tissue at 36 h postdosing. The lung AUCinf (410.16 h*μg g-1) was 77.39 times higher than the corresponding plasma AUCinf (5.30 h*μg g-1). The apparent elimination half-time for valnemulin in lung was 3.57 h. The advisable bioavailability and extensive distribution to lung tissue following a single dose of valnemulin may be desirable pharmacokinetic attributes for an antimicrobial drug used for the treatment and prevention of respiratory disease in swine.
Z. Zhang, C.Y. Zhang, J.P. Guo, L.X. Zhu, X.Y. Luo, R. Wang and Y.H. Liu, 2011. Pharmacokinetics and Lung Tissue Concentration of Valnemulin in Swine. Journal of Animal and Veterinary Advances, 10: 1824-1828.