The disclosure relates to a pharmaceutical composition comprising (a) glycopyrronium bromide at a dosage range of 0.5-100&mu；g per actuation； and (b) formoterol or a salt thereof such as formoterol fumarate at a dosage range of 1-25&mu；g per actuation； dissolved in an HFA propellant and a co-solvent such as ethanol, wherein said composition contains an amount of 1M hydrochloric acid (HCl) in the range of 0.1 - 0.3 &mu；g/&mu；l. The composition may additionally comprise one or more pharmaceutically active ingredients selected from the group consisting of beta-2-agonists, corticosteroids, antimuscarinic agents, and phosphodiesterase (IV) inhibitors； and beclometasone dipropionate. These pharmaceutical compositions, preferably as aerosol formulations, are suitable for use in the treatment or prophylaxis of respiratory diseases, such as chronic obstructive pulmonary disease (COPD).
