Certain novel substituted quinuclidine compounds having the ability to antagonize substance P and having the following formula: ##STR1## wherein Ar.sup.1 and Ar.sup.2 are each, independently, thienyl, phenyl, fluorophenyl, chlorophenyl or bromophenyl; X is --CONR.sup.3 R.sup.4, --CO.sub.2 R.sup.3, --CH.sub.2 OR.sup.3, --CH.sub.2 NR.sup.3 R.sup.4 or --CONR.sup.3 OR.sup.4 ; R.sup.1, R.sup.3 and R.sup.4 are each, independently, hydrogen or alkyl having 1 to 4 carbon atoms; R.sup.2 is alkyl having 1 to 4 carbon atoms; Y is alkylsulfonyl having 1 to 4 carbon atoms, N-alkyl-N-alkanoylamino (which may be substituted by halogen in the alkanoyl moiety) having 1 to 4 carbon atoms in the alkyl and the alkanoyl moieties, N-alkyl-N-alkylsulfonylamino (which may be substituted by halogen in the alkylsulfonyl moiety) having 1 to 4 carbon atoms in the alkyl and the alkyl sulfonyl moieties, alkenyl having 2 to 4 carbon atoms, alkynyl having 2 to 4 carbon atoms, halosubstituted alkyl having 1 to 4 carbon atoms, alkylamino having 1 to 4 carbon atoms, alkanoylamino (which may be substituted by halogen) having 1 to 4 carbon atoms or alkylsulfonylamino (which may be substituted by halogen) having 1 to 4 carbon atoms. These compounds are useful in the treatment gastrointestinal or central nervous system disorders and the alleviation of inflammatory diseases, asthma, pain and migraine in mammals and as the active ingredient in pharmaceutical compositions for treating such conditions.