| abstract |
A pyridopyrimidine or naphthyridine derivative represented by the general formula (I) (I) (wherein R1 is optionally substituted nitrogenous heterocyclic group, etc.; R2 is hydrogen or lower alkyl; R3 is hydrogen, optionally substituted lower alkyl, etc.; R4 is hydrogen, lower alkyl, COOH, etc.; R5 is hydrogen, optionally substituted aryl, etc.; and one of X and Y is CH and the other is nitrogen, or both of X and Y are nitrogen); or a pharmacologically acceptable salt of the derivative. They have excellent PDE V inhibitory activity and are useful as a preventive/remedy for erectile dysfunction. |