112735-03-2

A rapid-acting remedy for asthma having a bronchodilating action contains at least one pyrido?2,3-d!pyrimidine derivative represented by the general formula (A) or pharmaceutically acceptable salts or metal complexes thereof as an effective component: STR1 wherein R1 and R2 are the same or different and each of R1 and R2 is hydrogen, alkyl or benzyl; R3 is hydrogen, hydroxyl, dialkylaminomethyleneamino or --NH--X; X is hydrogen, alkyl, alkenyl, hydroxyl, amino, hydroxyalkyl, benzyl or acyl; R4 is hydrogen, alkyl, halogen, nitro, amino, hydroxyl, benzyloxy, cyano, carboxyl, alkoxycarbonyl, alkoxysulfonyl, aminosulfonyl, dialkylaminosulfonyl or sulfo; and R5 is hydrogen, alkyl or amino. The rapid-acting remedy for bronchial asthma is capable of relieving the symptom of laboring breath at the onset of asthma due to its excellent bronchodilating action. It can be used as a therapy not only for allergic asthma but also for various bronchial asthmas such as endogenous asthma, exogenous asthma and dust asthma.

The present invention relates to a novel pyrido[2,3-d]pyrimidine derivative having the formula (I): STR1 wherein each of R1 and R2, which may be the same or different, is a lower alkyl group; and each of R3 and R4, which may be the same or different, is hydrogen, halogen, hydroxy, nitro, amino, hydroxyamino, hydrazino, azido, a lower alkenylamino group or a lower alkylamino group which may optionally have hydroxy; and pharmaceutically acceptable salt thereof. These compounds are useful as anti-allergic agents, for example, for the treatment of bronchial asthma, urticaria, allergic rhinitis, allergic dermatoses or allergic conjunctivitis.