To provide a compound useful as an active ingredient of a pharmacological composition for the treatment of urinary storage symptoms, dysuria, lower urinary tract diseases, and the like. The inventors perfected the present invention after discovering that thiazole derivatives substituted at position 2 by pyrazinylcarbonylamino are exceptional muscarinic M3 receptor positive allosteric modulators and can be expected to serve as agents for the prevention or treatment of urinary bladder and urinary tract diseases involving bladder contraction mediated by muscarinic M3 receptors. The 2-acylaminothiazole derivatives or salts thereof of the present invention can be expected to serve as agents for the prevention or treatment of urinary bladder and urinary tract diseases involving bladder contraction mediated by muscarinic M3 receptors, e.g., underactive bladder and the like.本發明提供一種作為蓄尿障礙、排尿障礙及下尿道系疾病等治療用醫藥組成物的有效成分為有用之化合物。本發明者們發現於第2位由吡嗪基羰基胺基取代的噻唑衍生物為優良的毒蕈鹼M3受體正變構性(allosteric)調節劑，期待作為與介著毒蕈鹼M3受體之膀胱收縮相關的膀胱．泌尿道系疾病之預防或治療劑而完成本發明。本發明之2-醯胺基噻唑衍生物或其鹽可期待作為與介著毒蕈鹼M3受體之膀胱收縮相關的膀胱．泌尿道系疾病，例如低活動膀胱等排尿障礙的預防或治療劑使用。
