Compounds of formula I useful for inhibiting the pain enhancing effects of E-type prostaglandins are disclosed ##STR1## wherein A is a ring system in which the --CH(R.sup.3)N(R.sup.2)B--R.sup.1 and --OR.sup.4 groups are positioned in a 1,2 relationship to one another on ring carbon atoms. B is a ring system having R.sup.1 in a 1,3 or 1,4 relationship with the --CH(R.sup.1)N(R.sup.2)-- linking group. A, B, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are as defined in the specification and may be substituted. Also disclosed are pharmaceutically-acceptable salts, in vivo-hydrolysable esters and amides of compounds of formula I, pharmaceutical compositions containing such compounds, processes for preparing such compounds, and the use of such compounds as therapeutic agents.