The present work describes a reversed phase high-performance liquid chromatography (RP-HPLC) assay with diode array detection (DAD) for the determination of rhein, an active metabolite of diacerein, in spiked rabbit plasma. The plasma samples were subjected to one-step liquid-liquid extraction using a protein precipitating agent. The separation of rhein was achieved on an RP C18 hypersil-ODS column (250×4.6mm, 5μm). The mobile phase consisted of a binary mixture of methanol and water (15: 85 v/v, pH 4.7) run under the isocratic system at a flow rate of 1 ml.min-1, the wavelength of DAD was set at 210 nm. The method was validated for linearity, accuracy, precision, and stability according to the International Council for Harmonization (ICH guidelines). The calibration curve was linear over the range of 0.015-5 µg. ml-1 for rhein with the coefficient of regression (r2) of value 0.9980. Extraction recovery for rhein from rabbit plasma was in the range of 95.0% to 98.60% to different sample concentrations. The retention time of rhein was observed at 5.34 min. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 5 and 15 respectively. The assay method was successfully applied to the pharmacokinetic study of diacerein plain aqueous dispersion in albino rabbits.

Asadullah Madni, Muhammad Imran Khan, Mubashar Rehman, Nayab Tahir, Nadia Rai, Farzana Parveen, Muhammad Danish Saeed, Muhammad Abdur Rahim, Hassan Shah