Pharmacokinetics of thiamphenicol in experimentally infected chickens with Pasteurella multocida.

Thirty healthy chickens were randomly divided into three groups.The pharmacokinetics of thiamphenicol were investigated following single intravenous (15 mg/kg b.w.),and oral (30 mg/kg b.w.) administration in healthy chickens experimentally infected with Pasteurella multocida.Blood samples were collected at different intervals after administration of thiamphenicol.The thiamphenicol in plasma was extracted with and de-proteined by ethyl acetate and its concentrations in plasma were determined by high performance liquid chromatography (HPLC) with a limit of detection of 0.01 mg/L.The concentration-time data of thiamphenicol in plasma were analyzed with pharmacokinetic compartment analysis soft (3P97).The concentration-time data of thiamphenicol after i.v.administration were fitted to a two-compartment open model.The main pharmacokinetic parameters were as follows:V(c)(0.58±0.09) L/kg,t1/2α(0.11±0.03) h,t1/2β(0.95±0.18) h,AUC(11.99±0.90) mg/(L·h),CL(s) (1.26±0.10) L/(kg·h).The concentration-time data after oral adminstration in healthy and infected chicken were fitted to a one-compartment open model with first-order absorption.The main pharmacokinetic parameters in healthy chicken were as follows: lagtime(0.04±0.02) h,t1/2ka(0.16±0.08) h,t1/2ke(1.64±0.22) h,T(peak)(0.57±0.18) h,C(max)(6.34±0.56) mg/L,AUC (19.02±1.48) mg/(L·h),F 79.32%.The main pharmacokinetic in infected chicken parameters were as follows:lagtime 0.07±0.02 h,t1/2ka(0.54±0.26) h,t1/2ke(1.74±0.27) h,T(peak)(1.31±0.39) h,C(max)(5.28±0.73) mg/L,AUC(21.75±1.03) mg/(L·h),F 90.70%.The results showed that thiamphenicol was completely absorbed by the oral routes in chicken infected with Pasteurella multocida,but the pharmacokinetic parameters of t1/2(ka),T(peak) and lagtime were significantly lengthened(P0.05 or 0.01).