High Performance Liquid Chromatographic Assay of Ciprofloxacin in Human Plasma Using Fluorescence Detection

An accurate, sensitive and reproducible High Performance Liquid Chromatographic (HPLC) method for the quantitation of Ciprofloxacin in plasma using Acebutolol as the internal standard has been developed and validated. The procedure involves protein precipitation with 7% perchloric acid. The drug and the internal standard were eluted from a 4-μm stainless steel Novapak C18 column (3.9 x 150 mm) with an average particle size of 4 μm at room temperature with isocratic mobile phase consisting of 10.5% acetonitrile in sodium dihydrogen phosphate buffer (pH 3.9), at a flow rate of 2 ml/min., and monitored in a fluorescence detector set at excitation wavelength 280 nm and emission wavelength 455 nm. Each analysis required no longer than 14 min. Quantitation was achieved by measurement of the peak height ratio of the drug to the internal standard, and the limit of detection for ciprofloxacin was 25 ng/ml.The intraday coefficient of variation (CV) ranged from 5.5% to 10.6% and interday CV ranged from 4.7 to 5.9% at four different concentrations.The mean relative recovery was 101.6%. Stability test shows that ciprofloxacin is stable in plasma for at least four weeks when stored at -20oC. This method was applied for the determination of the pharmacokinetic parameters of ciprofloxacin after oral administration of 500 mg / tablet of two commercially available formulations to 6 human volunteers.