Simultaneous HPLC–UV determination of rhein and aceclofenac in human plasma

Diacerein and aceclofenac are prescribed for reducing the symptoms associated with osteoarthritis. We present a simple HPLC method with UV detection for simultaneous determination of rhein (the immediate metabolite of diacerein) and aceclofenac from human plasma samples. Sample preparation was accomplished through liquid–liquid extraction with ethyl acetate and chromatographic separation was performed on a reversed-phase ODS column. Mobile phase consisted of a mixture of acetate buffer and acetonitrile run under gradient at flow rate of 1.0 ml/min. Wavelength was set at 258 nm. The method was validated for linearity, accuracy, precision and stability. The calibration was linear over the range of 0.1–7.0 μg/ml for rhein and 0.5–20 μg/ml for aceclofenac using 500 μl plasma samples. Extraction recoveries were 85% for rhein and 70% for aceclofenac. The method can easily be adopted for high-throughput clinical and pharmacokinetic studies of above two-drug fixed dose combination formulations.