A new HPLC method for determination of ciprofloxacin in human plasma and its application in bioequivalence studies

A simple, rapid and sensitive isocratic reversed-phase HPLC method with UV detection is described based on external-standard calibration for determination of ciprofloxacin in plasma samples during bioequivalence studies. Both internal and external procedures were evaluated and the External-standard method demonstrated a high validity based on ICH criteria. After protein precipitation with acetonitrile and dichloromethane, chromatographic analysis of ciprofloxacin in plasma was carried out on au-bondapack C sub(18) column using acetonitrile:0.005 M tetrabutylammonium bromide (10:90) mixture, pH 2, as mobile phase. Quantitative determination was performed by ultraviolet detector at 278 nm. The method was specific and validated with a limit of detection of 20 ng/ml and limit of quantitation of 50ng/ml.The intra- and inter-day coefficients of variation were in the range of 1.51-4.48% and 4.02 7.3%, respectively. The recovery of method was 94.27 plus or minus 1.91%. The method was applied to a bioequivalence study of two formulations containing 500 mg ciprofloxacin.