A stability-indicating RP-HPLC method for simultaneous quantification of thirteen known and unknown impurities in fluticasone furoate–vilanterol–glycopyrronium combination products
Rigorous impurity monitoring of fixed-dose combination inhalation products containing fluticasone furoate, vilanterol, and glycopyrronium is essential for ensuring therapeutic efficacy and regulatory compliance. This study describes the development and validation of a stability-indicating reverse-phase liquid chromatographic (RP-HPLC) method designed for the simultaneous quantification of multiple degradation products. Separation was optimized using a BakerBond C18 stationary phase (5 µm, 250 × 4.6 mm) at 45 °C. The gradient elution utilized a potassium dihydrogen phosphate buffer (pH 2.2) and a binary organic phase of acetonitrile and methanol (75: 25, v/v) at a flow rate of 1.3 mL/min. To ensure detection sensitivity, UV wavelength switching was employed, monitoring at 210 nm for vilanterol and glycopyrronium derivatives and 248 nm for fluticasone-related species. Relative response factors (RRFs) were determined for thirteen characterized impurities, facilitating precise quantification in the absence of individual reference standards. Validation per ICH Q2(R2) guidelines confirmed the method’s selectivity, linearity (r2 > 0.998), and accuracy, with recoveries ranging from 80 to 120%. Precision studies yielded %RSD values between 6.02 and 13.76%, while stability testing confirmed sample integrity over 48 h. This robust analytical framework is highly suitable for routine quality control and impurity profiling of complex pulmonary fixed-dose combination formulations.