abstract |
There is provided compounds of formula IA and of formula IB, n wherein R 1 , R 2 , R 3 , R 4 and A have meanings given in the description, 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. |