A compound of the formula (1) or a pharmaceutically-acceptable salt wherein, for example, A is phenylene or heteroarylene; 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); compounds which 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.