Compounds of formulae (IA) and (IB) or pharmaceutically or veterinarily
acceptable salts thereof, or pharmaceutically or veterinarily acceptable solvates
of either entity, wherein R1 is C1 to C3 alkyl
substituted with C3 to C6 cycloalkyl, CONR5R6
or a N-linked heterocyclic group; (CH2)nHet or (CH2)nAr,
R2 is C1 to C6 alkyl; R3 is C1
to C6 alkyl optionally substituted with C1 to C4
alkoxy; R4 is SO2NR7R8; R5
and R6 are each independently selected from H and C1 to
C4 alkyl optionally substituted with C1 to C4 alkoxy,
or, together with the nitrogen atom to which they are attached, form a 5- or 6-membered
heterocyclic group; R7 and R8, together with the nitrogen
atom to which they are attached, form a 4-R10-piperazinyl group; R10
is H or C1 to C4 alkyl optionally substituted with
OH, C1 to C4 alkoxy or CONH2; Het is an optionally
substituted C-linked 5- or 6-membered heterocyclic group; Ar is optionally substituted
phenyl; and n is 0 or 1; are potent and selective cGMP PDE5 inhibitors useful in
the treatment of, inter alia, male erectile dysfunction and female sexual dysfunction
##STR1##
