Neutrophilia inhibitor

摘要

To provide an antineutrophilia agent effective for treatment of development and progress of acute infections, collagen diseases (chronic rheumatoid arthritis, Wegener's granulomatosis and Behcet's disease), chronic obstructive pulmonary disease (COPD), chronic bronchitis, pulmonary emphysema, small airway disease, gout, Cushing's syndrome, myelofibrosis, neoplastic neutrophilia, polycythemia vera and diseases caused by administration of steroid drugs. An antineutrophilia agent containing a 3(2H)-pyridazinone compound represented by the formula (I) or a pharmaceutically acceptable salt thereof [wherein each of R¹, R² and R³ is independently a hydrogen atom or a C_1-6 alkyl group, X is a halogen atom, cyano or a hydrogen atom, Y is a halogen atom, trifluoromethyl or a hydrogen atom, and A is a C_1-8 alkylene which may be substituted with a hydroxyl group].