A pharmaceutically acceptable salt of N-[2-(Diethylamino)ethyl]-N-(2-{[2-(4-hydroxy-2-oxo-2,3-dihydro-1,3-benzothiazol-7-yl)ethyl]amino}ethyl)-3-[2-(1-naphthyl)ethoxy]propanamide provided it is not the dihydrobromide or dihydrochloride salt； and the use of such a compound as a medicament (for example in the treatment of respiratory diseases (such as asthma or COPD).
