A DoE-based fast and synchronous quantification of rhein, aceclofenac, and diclofenac by RP-HPLC-DAD method in spiked Wistar rat plasma: application to pharmacokinetic studies

A fixed-dose combination of diacerein and aceclofenac (ACF) is commonly used in the treatment of osteoarthritis for their disease-modifying and analgesic effects, respectively. We introduce a simple, fast, sensitive, and green HPLC method for synchronous quantification of rhein (RH) (a primary metabolite of diacerein), ACF, and diclofenac (DL) (an active metabolite of ACF) in rat plasma using fenofibric acid as an internal standard (IS). The chromatographic conditions were optimized using Fractional Factorial and Box-Behnken design. Drugs were extracted by acetonitrile-methanol-based simple protein precipitation technique. The separation was performed on C-18 column (Phenomenex, 250 x 4.6 mm), using acetonitrile: phosphate buffer pH 3.5 (60:40, v/v) at a 1 mL/min flow rate in a 10 min run time and detected at 264 nm. As per the USFDA guidelines, the established method was validated. RH, ACF, and DL showed good linearity in the 25-3000, 50-6000, and 50-6000 ng/mL concentration ranges respectively. The precision and accuracy results were found to be well within the acceptable range, with average recovery ranging between 92.27 and 96.10%. The developed method was found to be stable and successfully used to determine the pharmacokinetic parameters in Wistar rats after oral administration of Dycerin A tablet.