The present invention provides compounds of formula (I), wherein R.sup.1 is a 5- or 6-membered aromatic heterocyclic group containing 1, 2, 3 or 4 heteroatoms selected from nitrogen, oxygen and sulphur, which group is optionally substituted; R.sup.2 is hydrogen, halogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy, CF.sub.3, OCF.sub.3, NO.sub.2, CN, SR.sup.a, SOR.sup.a, SO.sub.2 R.sup.a, CO.sub.2 R.sup.a, CONR.sup.a R.sup.b, C.sub.2-6 alkenyl, C.sub.2-6 alkynyl or C.sub.1-4 alkyl substitued by C.sub.1-4 alkoxy, where R.sup.a and R.sup.a R.sup.b each independently represent hydrogen or C.sub.1-4 alkyl; R.sup.3 is hydrogen, halogen, C.sub.1-6 alkyl, C.sub.1-6 -alkoxy substituted by C.sub.1-4 alkoxy or CF.sub.3 ; R.sup.4, R.sup.5, R.sup.6, R.sup.9a, R.sup.9b, A, X and Y are as defined in the specification; and m is zero or , and pharmaceutically acceptable salts and prodrugs thereof. The compounds are of particular use in the treatment or prevention of pain, inflammation, migraine, emesis and pos therpetic neuralgia.