The present invention provides a pharmaceutical composition which contains following (I) compound and their pharmaceutical acceptable salt as active ingredient:[wherein , R1represents C6-C10aryl group which may optionally substituted with a group selected from the susbstituted group α etc., R2represents C6-C10aryl group which may optionally substituted with a group selected from the susbstituted group α, etc., X represents hydroxyl group, C1-C6alkyloxy group etc.].本發明提供含如下式(I)化合物或其製藥容許鹽為有效成分之醫藥組成物:[上述式中、R1為可有選自取代基群α之基取代之C6-C10芳基等、R2為可有選自取代基群α之基取代之C6-C10芳基等、X為羥基、C1-C6烷氧基等]。