Validation of a sensitive HPLC/fluorescence method for assessment of ciprofloxacin levels in plasma and prostate...

Chronic bacterial prostatitis treatment consists of broad-spectrum antibiotic therapy for long periods of time. Drug penetration into the prostate makes the treatment a challenged. Ciprofloxacin is one of the most prescribed drugs for this treatment. A liquid chromatography with fluorescence detection method was developed and validated for determining ciprofloxacin concentrations in two different matrices: plasma and prostate microdialysate. Ciprofloxacin was separated on a C18 column eluted with a mobile phase constituted of a mixture of 0.4% aqueous triethylamine:methanol:acetonitrile (75:15:10, v/v/v) and 0.4% aqueous triethylamine:acetonitrile (88:12, v/v) for microdialysate and plasma samples, respectively. Linearity was obtained over a concentration range of 5-1000 ng/mL (microdialysate) and 10-2000 ng/mL (plasma), with coefficients of determination ≥0.9956. Precision was determined from the analysis of six quality control samples and showed RSD values <11.1 and 7.4% for intra and inter-assay precision, respectively. The accuracy ranged from 85.6 to 114.3%. The method was applied to a preliminary pharmacokinetic study to investigate ciprofloxacin concentrations in prostate, sampled by microdialysis, and plasma after a 7 mg/kg intravenous dose to Wistar rats. The method showed high sensitivity using only protein precipitation as plasma sample clean-up and was successfully applied to investigate ciprofloxacin prostate penetration.