Multiple analytical methods for determination of formoterol and glycopyrronium simultaneously in their novel combined metered dose inhaler

One of the major causes of mortality all over the world is chronic obstructive pulmonary disease (COPD). Recently approved combined inhaler of formoterol fumarate (FF) and glycopyrronium bromide (GLY) has been used in very low concentrations (µg level/actuation) doses in COPD patients. The first spectrophotometric and advanced highly sensitive liquid chromatography has been achieved successfully throughout this study, permitting validated analysis of dual combined inhaler in raw material as well as pharmaceutical inhaled dosage form. Three sensitive analytical methods were carried out for the simultaneous assay of FF and GLY in their novel combined Metered dose inhaler (MDI). The first method depends on measuring the first derivative amplitudes at 208.27 nm for FF and at 213.27 nm and 239.86 nm for GLY, respectively. The second method depends on measurement of the first derivative of the ratio spectra at 214 or 229 nm for FF and 240 or 259 nm for GLY, respectively. For the spectrophotometric methods, the linearity ranges were 0.48–9.6 µg/mL for FF and 0.9–18 µg/mL for GLY. For the third method, valid ion-pairing chromatographic method was carried out applying C(18) column and isocratic mobile phase of 60% v/v acetonitrile and 40% v/v deionized waster (pH 3.0) enclosing 0.025% sodium dodecyl sulfate, using UV detection adjusted to 210 nm and flow rate of 1.2 mL/min. For the ion-pairing chromatographic method, the linearity ranges were 0.048–4.8 µg/mL for FF and 0.09–9.0 µg/mL for GLY. The developed methods are reproducible, valid and offer efficient resolution between formoterol and glycopyrronium using spectrophotometric methods and highly sensitive and precise chromatographic method. The percent recoveries of the inhaled drugs in their MDI were good. The method was successfully established for the quantitative analysis of FF and GLY in their combined pharmaceutical inhaler capsules to validate the therapeutic efficiency of the combined drugs in quality control labs. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13065-019-0592-9) contains supplementary material, which is available to authorized users.