Quality by Design-based RP-HPLC Method for Estimation of Curcumin in Rat Plasma and Fecal Microbiota Extract-based Solid Self-nano Emulsifying Drug Delivery System

Background: Curcumin (CRM) is known to possess various therapeutic properties, such as anti-inflammatory and antidiabetic properties, and is, therefore, considered to be an effective therapeutic. Objective: A sensitive method for the estimation of CRM in plasma, as well as fecal matter-based solid self-nano emulsifying drug delivery system (S-SNEDDS), has been reported for the first time. Methods: A bioanalytical method was optimized using Box-Behnken Design having 13 runs and 3 responses. The optimized method was developed using methanol and water (70:30 v/v) with a flow rate of 1 mL/min. Quercetin was used as an internal standard. A specificity test was also performed for the developed CRM solid self-nano emulsifying drug delivery system. Results: The retention time of CRM was found to be 14.18 minutes. The developed method was validated and found to be linear in the range of 50-250 ng/mL with an R² of 0.999. Accuracy studies indicated that CRM had a percentage recovery of less than 105% and more than 95%, respec-tively. Precision studies were carried out for inter, intraday, and inter-analyst precision, and the %RSD was found to be less than 2%. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 3.37 ng/mL and 10.23 ng/mL, respectively. Stability studies for short-term, long term and freeze-thaw cycles showed a %RSD of less than 2%, indicating the stability of CRM in the plasma matrix. Moreover, the blank fecal microbiota extract slurry did not show any peak at the retention time of CRM in a CRM-loaded solid nanoemulsifying drug delivery system containing fecal microbiota extract indicating its specificity. Conclusion: Hence, the developed method can have clinical implications as it helps estimate CRM in blood samples and also provides a simple and sensitive method for the estimation of plant-based flavonoids along with fecal microbiota extract formulations.