PROBLEM TO BE SOLVED: To provide a method for producing a composition and a compound inhibiting MEK.SOLUTION: This invention relates to a series of new heterocyclic compounds that are useful in the treatment of hyperproliferative diseases, such as cancer and inflammation, in mammals, and discloses MEK inhibitors useful in the treatment of inflammatory conditions. A 6-oxo-1,6-dihydropyridazine compound having a specific substituent may include a tautomer, a metabolite, a resolved enantiomer, a diastereomer, a solvate, and a pharmaceutically acceptable salt thereof, and is a strong inhibitor of an MEK enzyme.COPYRIGHT: (C)2009,JPO&INPIT【課題】MEK阻害剤の提供。【解決手段】哺乳動物における癌及び炎症などの過剰増殖疾患の治療に有用である一連の新規な複素環式化合物に関する、また炎症性状態の治療に有用なMEK阻害剤を開示する。特定の置換基を有する6-オキソー1,6-ジヒドロピリダジン化合物は、互変異性体、代謝物、分割鏡像異性体、ジアステレオ異性体、溶媒和物、及び製薬的に許容できるそれらの塩類を含んでもよく、MEK酵素の強力な阻害剤である。【選択図】なし