Yoshitomi Pharmaceutical Industries, Ltd.

Shin-ichi Uesato

Hideki Ao

Kazuyuki Kawasaki

Yoshifumi Ikeda

Tsuyoshi Kuroda

Akihiko Moriguchi

8-Methoxy-quinolonecarboxylic acid derivatives of the formula ##STR1## wherein R.sub.1 is a hydrogen atom, a lower alkyl, a phenylalkyl or an ester residue hydrolyzable in the living body, R.sub.2 is a hydrogen atom or methyl and n is an integer of 1, optical isomers thereof, pharmaceutically acceptable salts thereof and hydrates thereof. The 8-methoxy-quinolonecarboxylic acid derivatives of the present invention have enforced and a wide range of in vitro and in vivo antibacterial effects against Gram-positive bacteria, while retaining a strong antibacterial effect against Gram-negative bacteria, that the conventional quinolonecarboxylic acid antibacterial agents have. In addition, the compounds of the present invention scarcely show problematic side-effects and are low toxic. Therefore, they are expected to show superior clinical effects as antibacterial agents.

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Takatsuki, Japan

Shin-ichi Uesato