| abstract |
A pyridopyrimidine or a naphthyridine derivative ofnthe formula (I):n nwherein R 1 is an optionally substituted nitrogen-containingnheterocyclic group, etc.; R 2 is H or a lower alkyl group;nR 3 is H or an optionally substituted lower alkyl group,netc.; R 4 is H, a lower alkyl group, COOH, etc.; R 5 is H, annoptionally substituted aryl, etc; one of X and Y is CH andnthe other is nitrogen, or both of X and Y are nitrogen; orna pharmaceutically acceptable salt thereof, these compoundsnexhibiting excellent PDE V inhibitory activities, and beingnuseful in the prophylaxis or treatment of penile erectilendysfunction, etc. |