Determination of roxithromycin in human plasma by high-performance liquid chromatography with spectrophotometric detection

A simple and reproducible method for the determination of roxithromycin in human plasma is presented. This method is based on liquid-liquid extraction with hexane-isoamylalcohol (98:2, v:v) and reversed-phase chromatography with spectrophotometric detection at 220nm. The mobile phase consists of methanol-15mM dihydrogen potassium phosphate (70:30, v:v), pH of the aqueous part of the mobile phase is 6.0. The column is operated at 60°C. Clarithromycin is used as the internal standard. The limit of quantitation is 0.5μg/ml and the calibration curve is linear up to 30 μg/ml. Within-day and between-day precision expressed by relative standard deviation is less than 5% and inaccuracy does not exceed 9%. The assay was used for pharmacokinetic studies. Copyright (C) 1999 Elsevier Science B.V.