| abstract |
Compounds of general formula (I), or pharmaceutically or veterinarily acceptable salts, solvates, polymorphs or pro-drugs thereof wherein: wherein R<1>, R<2>, R<3>, R<4>, X and A have the meanings given herein which are useful in the curative and prophylactic treatment of a medical condition for which inhibition of a cyclic guanosine 3',5'-monophosphate phosphodiesterase (e.g. cGMP PDE5) is desired. |