The present invention relates to a pharmaceutical formulation for use in the administration of a long-acting ² 2 -agonist by inhalation. In particular this invention relates to a chemically stable highly efficient formoterol HFA solution formulation to be administered by pressurised metered dose inhalers (pMDIs) characterized by a deep lung penetration. The invention also relates to methods for the preparation of said formulation and to its use in respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD).
