Fast and efficient related substance determination of Rilpivirine and Dolutegravir in combined HIV therapy with RP-HPLC

The abstract discusses the development and validation of a Related Substance RP-HPLC method for the simultaneous estimation of Rilpivirine and Dolutegravir in a combined pharmaceutical dosage form, following their FDA approval for HIV treatment. The developed method utilized a simple and economical approach, employing an LC-20 AT C18 column with a Water:Methanol (70:30) mobile phase at a flow rate of 1 ml/min, and detection at 258 nm. Retention times for Rilpivirine and Dolutegravir were determined to be 3.82 min and 7.51 min, respectively, while Rilpivirine and Dolutegravir impurity retention times were found to be 4.32 min and 7.12 min, respectively. The method demonstrated excellent linearity for Rilpivirine impurity (5.0-15.0 μg/ml) and Dolutegravir impurity (7.5-22.5 μg/ml). Limits of detection (LOD) were 0.079μg/ml and 0.145μg/ml for Rilpivirine and Dolutegravir impurities, while limits of quantification (LOQ) were 0.241μg/mL and 0.441μg/mL, respectively. The proposed method was successfully applied for the simultaneous estimation of both drugs and their related impurities in a commercial combined dosage form.