Pharmaceutically active compounds

摘要

There is provided compounds of formula IA and of formula IB,wherein R1, R2, R3, Het1 and X have meanings given in the description, which are useful in the curative and prophylactic treatment of medical conditions for which inhibition of a cyclic guanosine 3',5'-monophosphate phosphodiesterase (e.g. cGMP PDE5) is desired.