The invention provides a composition which comprises (a) a PDE3/PDE4 inhibitor which is 9,10-Dimethoxy-2-(2,4,6-trimethylphenylimino)-3-(N-carbamoyl-2-aminoethyl)-3,4,6,7-tetrahydro-2H-pyrimido[6,1-a]isoquinolin-4-one or a pharmaceutically acceptable acid addition salt thereof and (b) a β2-adrenergic receptor agonist.