Rapid RP-HPLC method for simultaneous quantification of fenoterol hydrobromide and ipratropium bromide in breathable and respirable fraction from nebulizers

• A novel technique for particle size distribution measurement for fenoterol hydrobromide with ipratropium bromide. • Research study will help to evaluate in vitro respirable fraction generated through Next Generation Impactor (NGI) instrument. • Accurate and precise RP-HPLC method for the simultaneous determination of fenoterol hydrobromide with ipratropium bromide. The present research study was designed to evaluate the breathable fraction as well as the aerodynamic characteristics of the fenoterol hydrobromide (FEN) and ipratropium Bromide (IPR) using a Next Generator Impactor (NGI) and sensitive reverse phase high pressure liquid chromatography. The aerodynamic particle size distribution (APSD) is measured using the NGI, a cascade impactor instrument. The APSD mimics particle deposition in various respiratory tracts after inhalation depending on the aerodynamic diameter of the medication. The samples were analysed using X-bridge C18 (50 mm x 4.6 mm), 3.5 µm column with mobile phase consisting of 80:20 % v/v mixture of heptane-1-sulfonic acid sodium salt and acetonitrile. The analytical technique was validated and the respirable fraction of the nebulized dose was calculated as an extension of the method application. The average respirable mass (≤ 5μm in particle size, penetrate deep into the human lungs) for Fenoterol hydrobromide and Ipratropium bromide were observed 226.596 µg and 112.357 µg, respectively. The average breathable fraction (the portion of aerosol particles inhaled by human) for Fenoterol hydrobromide and Ipratropium bromide were observed 294.901 µg and 146.472 µg, respectively. The analytical technique introduced to evaluate breathable mass and respirable mass of Fenoterol hydrobromide and Ipratropium bromide nebulizer solution produces a reliable result with high sensitivity and reproducibility. The shorter runtime and cost effectiveness enhance the method’s suitability to its routine use in quality control. The presented work enhances the applicability for routine aerodynamic assessment with compliance of regulatory and pharmacopeial guidelines in pharmaceutical industry.