[Problem] To provide a compound having excellent
platelet aggregation inhibitory activity.[Means for Resolution] It was found that
quinolone derivatives characterized in that these have lower
alkyl, cycloalkyl or the like at the 1-position; —N(R0)C(O)-lower alkylene-CO2R0, lower alkylene-CO2R0, lower alkenylene-CO2R0, —O-lower alkylene-CO2R0, —O-(lower alkylene which may be substituted with —CO2R0)-
aryl or —O-lower alkenylene-CO2R0 (wherein R0 is H or lower
alkyl) at the 3-position;
halogen at the 6-position; and amino group substituted with a
substituent group having a ring structure at the 7-position, respectively, or pharmaceutically acceptable salts thereof, has excellent P2Y12 inhibitory activity. In addition, it was confirmed that these
quinolone derivatives also have excellent
platelet aggregation inhibitory activity. Based on the above, these
quinolone derivatives or pharmaceutically acceptable salts thereof are useful as
platelet aggregation inhibitors.