Rapid simultaneous determination of indacaterol maleate and glycopyrronium bromide in inhaler capsules using a validated stability-indicating monolithic LC method

BACKGROUND Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. A combination of indacaterol maleate with glycopyrronium bromide has recently been approved as a once-daily maintenance therapy in patients with COPD. The very low dose (μg level/capsule) renders the analysis of such products challenges. This study reports for the first time about HPLC method for the quality control of such combination and it is a stability indicating at the same time. RESULTS A rapid, simple, precise and reproducible HPLC method was developed and validated for simultaneous determination of indacaterol maleate and glycopyrronium bromide using tenoxicam as an internal standard. The chromatographic separation was achieved on an onyx monolithic C18 column (100 × 4.6 mm) using a mobile phase consisting of acetonitrile and 30 mM phosphate buffer (pH 3.5) (30:70, v/v), run at a flow rate of 2 mL/min with UV detection at 210 nm. The total analysis time was less than 3 min. The HPLC method was validated for linearity, limits of detection and quantitation, precision, accuracy, system suitability and robustness. Calibration curves were obtained in the concentration ranges of 1-44 µg/mL for indacaterol maleate and 0.5-20 µg/mL for glycopyrronium bromide. Stability tests were done through exposure of the analyte solution for different stress conditions and the results indicate no interference of degradants with HPLC method. CONCLUSIONS The method was successfully applied for the quantitative analysis of indacaterol maleate and glycopyrronium bromide both individually and in a combined pharmaceutical inhaler capsules to support the quality control and to assure the therapeutic efficacy of the two drugs. The simple procedure involved in sample preparation and the short run-time added the important property of high throughput to the method. Graphical abstract Chemical structures and representative HPLC chromatogram of indacaterol maleate (IND; 22 μg/mL), glycopyrronium bromide (GLY; 10 μg/mL) and tenoxicam (IS, 15μg/mL) in commercial capsules.