Stability Indicating RP-HPLC Method Development and Validation for the Simultaneous Estimation of Allopurinol and Lesinurad in Bulk and its Dosage Form

For the simultaneous estimation of Allopurinol and Lesinurad in bulk and combined pharmaceutical dosage forms, a novel, precise, and stability-indicating reverse-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated. An Inertsil ODS C18 column with an isocratic mobile phase of phosphate buffer (pH 3.0) and acetonitrile in a 70:30 v/v ratio was used to optimize the chromatographic separation. The detection was carried out at a wavelength of 255 nm, with the flow rate maintained at 1.5 ml/min. With correlation coefficients (R2) greater than 0.999 for both drugs, the method was validated in accordance with ICH Q2(R1) guidelines and demonstrated excellent linearity over the concentration ranges of 75–375 g/ml for Allopurinol and 50–250 g/ml for Lesinurad. Studies of precision revealed %RSD values below 2%, confirming intermediate precision and repeatability. Recovery studies provided evidence of accuracy, with results ranging from 100.60 percent to 99.14 percent. Additionally, the method was able to withstand deliberate changes in flow rate and mobile phase composition. The method's ability to indicate stability was confirmed by forced degradation tests conducted in thermal, photolytic, acidic, basic, oxidative, and thermal conditions. The validated method is suitable for routine quality control, assay, and stability analysis of Allopurinol and Lesinurad in pharmaceutical preparations due to its simplicity, sensitivity, and dependability.