Stability Indicating Method Development and Validation for the Simultaneous Estimation of Azilsartan and Chlorthalidone in their Bulk and Pharmaceutical Dosage Forms by RP-UPLC

Aim: The present study is aimed towards developing and validating novel RP-UPLC analytical method for the analysis of Azilsartan and Chlorthalidone in their pharmaceutical formulations and to carry out stability studies by forced degradation to ascertain the stability of selected drugs. The proposed method was challenging as the method used in the study is novel for the estimation of antihypertensive drugs. Materials and Methods: The solubility studies of Azilsartan and Chlorthalidone were carried out at 25°C using various solvents and buffers. The solubility studies revealed that the selected drugs were soluble in methanol, water and acetonitrile. Hence, a mobile phase system consisting of Acetonitrile: Water: Methanol in the ratio of 20: 40: 40 v/v/v is used. The analysis of the drugs is accomplished using Phenomenex C18 column (4.5 μm, 250 × 2.2 mm ID) at 258 nm. Results and Discussion: The method developed is then validated according to the guidelines of ICH. The analysis results reveal that, method developed is within the acceptance limits for all the validated parameters. The forced degradation studies revealed that 9.9% of Azilsartan degradation is observed in peroxide presence and 5.6% of Chlorthalidone degradation is observed in the presence of acid solution. Summary and Conclusion: From the results of the study for the selected drugs, the sample recoveries in all the formulations were within the limits, hence the proposed method can be conveniently and easily adopted to the determination of Chlorthalidone and Azilsartan in combined formulation.