Integration of pharmacokinetic and pharmacodynamic indices of valnemulin in broiler chickens after a single intravenous and intramuscular administration
2014
Zhao, Dong-Hao | Zhou, Yu-Feng | Yu, Yang | Shi, Wei | Yang, Xue | Xiao, Xia | Deng, Hui | Qiao, Guilin (Gary) | Fang, Bing-Hu | Liu, Ya-Hong
The antibacterial efficacy of valnemulin against Staphylococcus aureus was studied ex vivo in broiler chickens after intravenous and intramuscular administration at a dose of 10 mg/kg bodyweight (BW). The minimum inhibitory concentrations (MICs) of valnemulin against S. aureus strains ATCC 25923 in broth and serum were 0.12 and 1 µg/mL, respectively. The MIC50 and MIC90 of valnemulin against all susceptible S. aureus strains isolated from chickens in the test population were 0.06 and 0.12 μg/mL, respectively. Protein binding, which greatly influences the efficacy of valnemulin, was assayed by equilibrium dialysate in vitro. A high binding fraction of 86.2% was found, which seems in good agreement with the difference of bacterial susceptibility tests observed in broth and serum.The surrogate index of AUC0–24/MIC required for the lowest bacteriostatic effect, and 2 log10CFU reduction in bacterial count were 24.4 h and 38.0 h, respectively. The required daily dose of valnemulin for a bacteriostatic activity was calculated to be 15 mg/kg BW based on the MIC90 of 0.12 µg/mL. Considering the slow disposition process of valnemulin and an AUC0–24 h value of more than 10-fold obtained from diseased animals, a suggested dose of 3 mg/kg BW is sufficient to achieve a satisfactory therapeutic efficacy in infected broilers. Due to the time-dependent antibacterial characteristics of valnemulin, the recommended daily dose should be split into two or three sub-doses to achieve the highest effectiveness while diminishing the risk of development of bacterial resistance.
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