Concurrent Quantification of AT1 Receptor Antagonists Using a Robust Single-Run Isocratic RP-HPLC Approach: Optimized Analysis and Validation

A robust reverse-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous separation and quantification of five Angiotensin II receptor antagonists: Azilsartan medoxomil (AZIL), Olmesartan medoxomil (OLM), Telmisartan (TEL), Valsartan (VAL), and Losartan potassium (LOS). Chromatographic separation was performed using an isocratic mobile phase of acetonitrile (ACN) and acetate buffer (pH 3) in a 60:40 ratio on a Kinetex® C18 column (250×4.6 mm, 5 µm) at a flow rate of 1 mL/min. A UV detector set at 254 nm monitored the elution, with distinct peaks corresponding to each drug. The method was validated by assessing specificity, linearity (10-50 µg/mL, R² > 0.999), system suitability, precision (% RSD < 2%), robustness, limits of detection and quantification (LOD, LOQ), and accuracy (recoveries of 95.41% to 105.30%). All formulations analyzed met their labeled claims as per ICH Guidelines. This method enabled the efficient and accurate analysis of all five Angiotensin II receptor antagonists in a single run, making it suitable for routine quality control and pharmaceutical analysis. Isocratic development in multicomponent HPLC is beneficial because it is simpler, more reproducible, easier to transfer between labs, requires less equilibration time, and is more cost-effective.