CAPILLARY ELECTROPHORESIS WITH LASER-INDUCED FLUORESCENCE DETECTION, AN ADEQUATE ALTERNATIVE TO HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY, FORTHE DETERMINATION OF CIPROFLOXACIN AND ITS METABOLITE DESETHYLENECIPROFLOXACIN IN HUMAN PLASMA

A method to determine plasma concentrations of ciprofloxacin and its m etabolite desethyleneciprofloxacin (M1) by CE with HeCd laser-induced fluorescence detection is described. Following precipitation of protei ns and centrifugation supernatant is injected hydrodynamically (10 s, 0.5 p.s.i.) into the capillary. Overall analysis time for the quantifi cation of both analytes was 7 min. The total amount of plasma needed f or multiple injections (n>5) was 10-20 mu l. Data on accuracy and prec ision are presented. The assay performance is compared to the specific ations of a validated HPLC method, which is routinely used for the qua ntification of ciprofloxacin and M1 in body fluids. Both methods showe d comparable accuracy and precision for both analytes throughout the w hole working range (inter-day precision <9%; inter-day accuracy 96-110 %). The limit of quantification (LOQ) of 20 mu g/l (Mi 10 mu g/l) for the CE procedure was slightly higher than for the HPLC method, where 1 0 mu g/l (M1 2.5 mu g/l) was determined. However, application of the m ethods to human plasma samples derived from a clinical study proved th at comparable results are obtained and that the sensitivity of the HPC E method was sufficient to fully describe typical plasma concentration time profiles of ciprofloxacin and its metabolite M1. Both the adequa te sensitivity and the required smaller sample volume compared to HPLC indicate that the method is feasible for clinical studies where sampl e amounts are limited, e.g., studies to investigate pharmacokinetics i n pediatric patients. Preclinical studies form another possible applic ation of this technique.