The present invention relates to compounds of formula (I) wherein: R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are selected from a variety of suitable aromatic substituents; R.sup.6 is hydrogen, C.sub.1-6 alkyl, C.sub.3-7 cycloalkyl, C.sub.3-7 cycloalkylC.sub.1-4 alkyl, phenyl, or C.sub.2 -alkyl substituted by C.sub.1-4 alkoxy or hydroxy; R.sup.7 is hydrogen, C.sub.1-6 alkyl, C.sub.3-7 cycloalkyl, C.sub.3-7 cycloalkylC.sub.1-4 alkyl, phenyl, C.sub.2-4 alkyl substituted by C.sub.1-4 alkoxy or hydroxy, or the group C(.dbd.NR.sup.c)NR.sup.a R.sup.b ; or R.sup.6 and R.sup.7, together with the nitrogen atom to which they are attached, form an optionally substituted saturated heterocyclic ring of 4 to 7 ring atoms which may optionally contain in the ring one oxygen or sulphur atom or a group selected from NR.sup.8, S(O) or S(O).sub.2 ; or R.sup.6 and R.sup.7, together with the nitrogen atom to which they are attached, form a piperidino ring substituted by a spiro-fused indene or indoline group, each of which may be unsubstituted or substituted; R.sup.8 is hydrogen, C.sub.1-4 alkyl, hydroxyC.sub.1-4 alkyl or C.sub.1-4 alkoxyC.sub.1-4 alkyl; R.sup.9a and R.sup.9b are each independently hydrogen or C.sub.1-4 alkyl, or R.sup.9a and R.sup.9b are joined so, together with the carbon atoms to which they are attached, there is formed a C.sub.5-7 ring; X is selected from --CH.sub.2 CH.sub.2 --, --COCH.sub.2 -- or --CH.sub.2 CO--; and Y is hydrogen, or C.sub.1-4 alkyl optionally substituted by a hydroxyl group; or a pharmaceutically acceptable salt thereof. The compounds are of particular use in the treatment or prevention of pain, inflammation, migraine, emesis and postherpetic neuralgia. ##STR1##