A method is provided for the treatment and/or prophylaxis of cardiovascular diseases or eating disorders in a human or non-human mammal, which comprises administering to a human or non-human mammal in need thereof, an effective, non-toxic amount of a compound of formula (I): ##STR1## or a tautomeric form thereof and/or a pharmaceuticlaly acceptable salt thereof and/or a pharmaceutically acceptable solvate thereof, in which A.sup.1 represents a substituted or unsubstituted aromatic heterocyclyl g...