1. In vivo pharmacokinetic and pharmacodynamic study and cutoff of florfenicol against Riemerella anatipestifer in ducks.
- Author
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Zhang HL, Li FL, Chen HY, Qin DM, Sun SJ, Zhang MM, Ding HZ, and Liu Y
- Abstract
Riemerella anatipestifer causes serious infections, characterized by septicemia and serositis, in ducks and geese. R. anatipestifer is mainly controlled through antimicrobial chemotherapy. This study investigated the pharmacokinetic/pharmacodynamic (PK/PD) integration of florfenicol (FF) against R. anatipestifer by establishing a systemic infection model in ducks. For PK studies, FF was administrated intramuscularly (i.m.) at single doses of 2.5, 10, 20, and 40 mg/kg body weight. The concentrations of FF in blood, lung, and liver were determined. FF was rapidly eliminated in R. anatipestifer-infected ducks with T
1/2kel values of 1.67, 2.2, and 1.62 h in the plasma, lung, and liver, respectively. For PD analysis, the infected ducks were administered FF via the i.m. route at doses of 5-80 mg/kg body weight, using 2 dosing regimens involving the administration of FF either once or twice over 24 h. The bacteria were counted 24 h after drug administration. Bactericidal effects in tissues (including those of the heart, liver, spleen, lung, kidney, and brain) were achieved at doses of ≥20 mg/kg following 2 i.m. injections of FF within 24 h. The data obtained were fitted to a sigmoidal Emax model. The results demonstrated that AUC24h /minimum inhibitory concentration (MIC) (R2 = 0.930) and Cmax /MIC (R2 = 0.930) were the optimal PK/PD parameters for describing the antibacterial activity of FF. The magnitudes of AUC24h /MIC and Cmax /MIC required to produce a drop of 3 Log10 CFU/mL in the bacterial count were 58.56 h and 15.10, respectively. The MIC distribution of 164 R. anatipestifer strains for FF ranged from 0.25 to 16 μg/mL. Both the values of COWT derived from the ECOFFinder program and the COPD based on a 10,000-subject Monte Carlo simulation of FF against R. anatipestifer were 1 μg/mL, confirming that infections caused by strains with MIC ≤ 1 μg/mL could be effectively treated. Our study results may prove useful in optimizing FF regimens to treat R. anatipestifer infections., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024. Published by Elsevier Inc.)- Published
- 2024
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