PURPOSE: To obtain the subject derivative shown by a prescribed formula, having both immediate bronchodilatory action and preventive antiallergic action and a long prolonged time, useful as a medicine for bronchial asthma.

CONSTITUTION: This derivative is expressed by the formula (Ra1 and Rb1 are each an alkyl; Rc1 is amino or an alkylamino; Re1 is an alkyl) in detail, such as 5-amino-1,3-diethyl-7-methylpyrido[2,3-d]pyrimidine-2,4-dione. The objective derivative, for example, is preferably obtained by dissolving 1-benzyl-5- chloropyrido[2,3-d]pyrimidine-2,4-dione and sodium azide in dimethylformamide, adding water to the solution, and collecting precipitate crystal by filtration.