A compound of formula (I) and salts and solvates thereof, in which: R0 represents hydrogen, halogen or C1-6 alkyl； R1 represents hydrogen, C1-6alkyl, C2-6 alkenyl, C2-6 alkynyl, haloC1-6alkyl, C3-8cyloalkyl, C3-8cycloalkylC1-3alkyl, arylC1-3alkyl or heteroarylC1-3alkyl； R2 represents an optionally substituted monocyclic aromatic ring selected from benzene, thiophene, furan and pyridine or an optionally substituted bicyclic ring attached to the rest of the molecule via one of the benzene ring carbon atoms and wherein the fused ring A is a 5- or 6-membered ring which may be saturated or partially or fully unsaturated and comprises carbon atoms and optionally one or two heteroatoms selected from oxygen, sulphur and nitrogen； and R3 represents hydrogen or C1-3 alkyl, or R1 and R3 together represent a 3- or 4-membered alkyl or alkenyl chain. A compound of formula (I) is a potent and selective inhibitor of cyclic guanosine 3'5'-monophosphate specific phosphodiesterase (cGMP specific PDE) having a utility in a variety of therapeutic areas where such inhibition is beneficial, including the treatment of cardiovascular disorders.
