Compounds of formula (I), and salts and prodrugs thereof: ##STR1## wherein Q is the residue of an optionally substituted azabicyclic ring system;the dotted line represents an optional double bond;X represents H, --OH, .dbd.O or halo;R.sup.1 represents H, phenyl or thienyl, which phenyl or thienyl groups may be optionally substituted by halo or trifluoromethyl;R.sup.2 represents phenyl, thienyl or benzyl, any of which groups may be optionally substituted by halo or trifluoromethyl; andR.sup.3, R.sup.4 and R.sup.5 independently represent H, C.sub.1-6 alkyl, C.sub.2-6 alkenyl, C.sub.2-6 alkynyl, halo, cyano, nitro, trifluoromethyl, trimethylsilyl, --OR.sup.a, SR.sup.a, SOR.sup.a, SO.sub.2 R.sup.a, --NR.sup.a R.sup.b, --NR.sup.a COR.sup.b, --NR.sup.a CO.sub.2 R.sup.b, --CO.sub.2 R.sup.a or --CONR.sup.a R.sup.b ; andR.sup.a and R.sup.b independently represent H, C.sub.1-6 alkyl, phenyl or trifluoromethyl, are tachykinin receptor antagonists. They and compositions thereof are useful in therapy.