This invention relates to stable pharmaceutical solution formulations suitablefor aerosol administration containing an anticholinergic of formula (I)wherein X- is a pharmaceutically acceptable anion. More particularly, thisinvention relates to stable pharmaceutical solution formulations suitable foraerosol administration containing an anticholinergic of formula (I) in anenvironmentally safe hydrofluorocarbon (HFC) as a propellant, together with anorganic compound as a cosolvent wherein either an inorganic acid or an organicacid is added to the aerosol solution formulation.
