Pharmacokinetics and bioequivalence study of rhein as the main metabolite of diacerein

Abstract

A simple, rapid and fully-validated liquid chromatographic method (RP - HPLC) with fluorescence detection was developed for the analysis of rhein (as the main metabolite of diacerein) in human plasma. The separation was performed using an ODS C₁₈ column with a mobile phase consisted of acetonitrile:methanol:phosphate buffer pH 6.8 and the flow rate was1.0 mL/min. The flourimetric detection was performed at 2 excitation wavelengths ʎ_ex = 440 nm & 338 nm and one emission wavelength at ʎ_em = 520 nm. The developed method was validated according to Food and Drug administration (FDA) guidelines for bioanalytical method validation. The pharmacokinetic parameters of the test and the reference were determined and the analysis of variance (ANOVA) between parameters of the two brands was calculated. The relative bioavailability was found to be 89%. This method was successfully applied for the routine bioequivalence analysis of diacerein in plasma.