Determination of antofloxacin concentration in rabbits plasma by high performance liquid chromatography and its pharmacokinetics

Objective: To develop a high performance liquid chromatography method to assess the concentration of antofloxacin in rabbit plasma,and explore the drug metabolism of antofloxacin in rabbits Kinetic characteristics.Methods: Antofloxacin tablets were taken,powdered,added to 0.5% sodium carboxymethyl cellulose solution and mixed.The solution was intragastric administrated to rabbits at a dose of 25 mg/kg.Blood samples were collected.Following protein precipitation,the analytes were separated on a Phenomenex C₁₈ column(250 mm×4.6 mm,4μm),with a mobile phase consisting of acetonitrile 50 mmol/L,citric acid solution 1 mmol/L,ammonium acetate solution(19:80:1,volume/volume) at a flow rate of 1.0 ml/min,and the eluent was detected at 295 nm,column temperature was 40℃.Results: Linear calibration was generated over antofloxacin's concentration range of 0.164 to 10.5μg/ml for plasma samples.Intra-and inter-days precision was<10%,and the accuracy of the relative error was <5%,which were acceptable for all quality control.Samples with relative errors were within the prescribed scopes,including the lowest limit of quantification of 0.164μg/ml.The mean recovery of antofloxacin from plasma was >80%.Pharmacokinetic parameters of antofloxacin in rabbits were estimated as follows:the area under concentration-time curve was(46.17±13.99) mg·L^-1·h^-1,the time peak was(0.9±0.14) h,the peak concentration was(5.15±0.54) mg/L,the half time was(11.98±4.02) h,and the clearance rate was(0.58±0.19) L·kg^-1·h^-1.Conclusions: This specific,sensitive and precise method is suitable for the pharmacokinetic study of antofloxacin in rabbits.