A New RP-HPLC Method for Simultaneous Estimation of Ribociclib and Letrozole in Its Pure and Tablet Dosage Form as Per ICH Guidelines

Abstract

A simple, precise, and reliable RP-HPLC method was developed and validated for the simultaneous estimation of Letrozole and Ribociclib in bulk and pharmaceutical dosage forms in accordance with ICH Q2(R1) guidelines. Chromatographic separation was achieved using a Waters C18 column (4.6×250mm, 5 µm) with a mobile phase of 0.1% ortho phosphoric acid buffer and methanol (25:75 v/v) at a flow rate of 1.0 mL/min, and detection wavelength of 227 nm. Retention times were 2.04 min for Letrozole and 2.52 min for Ribociclib, with system suitability parameters meeting all acceptance criteria. Validation results demonstrated excellent linearity (R² = 0.999), high accuracy (recoveries 99–101%), precision (%RSD < 1%), and sensitivity with low LOD and LOQ values. Robustness and ruggedness studies confirmed the method’s reliability under deliberate variations in flow rate and mobile phase composition, while intermediate precision showed consistent performance across days and instruments. Overall, the developed method is simple, cost-effective, accurate, and sensitive, making it highly suitable for routine quality control, stability studies, batch release testing, and regulatory applications for Letrozole and Ribociclib formulations.