A compound of the formula (1) or a pharmaceutically-acceptable salt, or pro-drug thereof; wherein, for example, Z is CH or nitrogen, R.sup.4 and R.sup.5 together are either --S--C(R.sup.6).dbd.C(R7)-- or --C(R.sup.7).dbd.C(R.sup.6)--S--; R.sup.6 and R.sup.7 are independently selected from hydrogen, halo, nitro, cyano, hydroxy, fluoromethyl, difluoromethyl, trifluoromethyl, trifluoromethoxy, carboxy and carbamoyl; A is phenylene or heteroarylene; n is 0, 1 or 2; r is 1 or 2; R.sup.1 is halo, cyano or carboxy; Y is selected from --C(O)R.sup.2, --C(O)OR.sup.2, --C(O)NR.sup.2R.sup.3, -(1-4C)alkyl [optionally substituted] -(2-4C)alkenyl, --SO.sub.2NR.sup.2R.sup.3, and --S(O).sub.cR.sup.2 (wherein c is 0, 1 or 2); R.sup.2 and R.sup.3 are independently selected from hydrogen, --O(1-4C)alkyl, --S(1-4C)alkyl, --N(1-4C)alkyl, heterocyclyl, aryl, and (1-4C)alkyl [optionally substituted]; possess glycogen phosphorylase inhibitory activity and accordingly have value in the treatment of disease states associated with increased glycogen phosphorylase activity. Processes for the manufacture of compounds and pharmaceutical compositions containing them are described.