The invention provides (R)-1-[3-(R)-cyclohexyl-hydroxy-phenyl-methyl)-isoxazol-5-ylmethyl]-3-(3-fluoro-phenoxy)-1-azonia-bicyclo[2.2.2]octane 2-hydroxy ethanesulfonate, pharmaceutical compositions containing the compound and its use as a muscarinic antagonists, for the treatment of chronic obstructive pulmonary disease.