Abstract: The invention provides a drug which inhibits BCRP. A breast cancer resistance protein inhibitor containing, as an active ingredient, a diphenylacrylonitrile derivative represented by the following formula (1): [wherein, each of 8 R's, which are the same or different from one another, represents a hydrogen atom, a hydroxyl group, a nitro group, an amino group, an acetylamino group (—NHCOCH3 group); a cyano group (—CN group); a formyl group (—CHO group), —COOR1 (R1 is hydrogen or C1-C4 alkyl), —O(CH2)nCOOR2 (n=1?7: R2 is hydrogen or C1-C4 alkyl), —OOCCH2CH2COOR3 (R3 is hydrogen, C1-C4 alkyl, (Z)-2-(3,4-dimethoxy-phenyl)-3-(4-hydroxy-phenyl)-acrylonitrile, or glycopyranosyl), a C1-C8 alkoxy group, a C1-C4 alkyl group, a halogen atom, a C1-C4 alkoxy C1-C4 alkoxy C1-C4 alkoxy group, a C2-C8 acyloxy group, a C2-C8 halogenoacyloxy group, a methylenedioxy group, a trifluoromethyl group, a phosphate group (i.e., —OP(O) (OH)2) or a salt thereof, a sulfate group (i.e.

Abstract: The invention relates to a specific cyclooxygenase 2 inhibitor which comprises, as an active ingredient, 2-(2,6-dichloro-4-hydroxyanilino)phenylacetic acid represented by the following formula (1): ##STR1## or a salt thereof, as an anti-inflammatory agent. The compound specifically inhibits cyclooxygenase 2 without inhibiting cyclooxygenase 1 activity and thus it is low in toxicity and safe.

Abstract: A diarylheptanoide derivative of the following formula (1), ##STR1## and a drug composition comprising this compound, such as a 5-lipoxygenase inhibitor, an antiinflammatory agent, and the like. The diarylheptanoide derivative (1) is effective for treating and preventing various inflammatory diseases due to its strong 5-lipoxygenase inhibiting effect.