Spiro[cyclopropane-1,2'-indolin]-3'-ones of the general formula: ##STR1## wherein the ring A is a substituted or unsubstituted phenyl ring and Z is hydrogen, a substituted or unsubstituted alkyl group or a substituted or unsubstituted acyl group and their pharmaceutically acceptable salts have gastric acid secretion suppressing activity, antiinflammatory activity and analgesic activity.
Spiro [cyclopropane-1, 2'-[2H] indol]-3'(1'H)-ones with various substituents on the benzene ring and at the 1'-position were synthesized. Investigation of their biological activities revealed that significant anti-inflammatory and analgesic activities were exhibited by some compounds of this series. Their structure-activity relationships are discussed.