Comparative Antibacterial Activity of New Quinolone-Carboxylic Acid Derivatives

In vitro and in vivo antibacterial activities of new quinolone-carboxylic acid derivatives are described. A compilation of MICs of nalidixic acid, pipemidic acid, and seven new quinolones (norfloxacin, ofloxacin, enoxacin, ciprofloxacin, pefloxacin, NY-198, and AM-833) is presented. The new quinolones exhibit potent antibacterial activity against the enteric gram-negative bacteria. These compounds also are active against Pseudomonas aeruginosa and gram-positive bacteria. MICs of these agents for Bacteroides fragilis are higher. Excellent bactericidal activity of new quinolones, the result of their strongly inhibitory activity against bacterial DNA gyrase, was found to be characteristic. The bioavailabilities of the new quinolones are discussed from the standpoint of their physicochemical properties. The quinolone compounds are classified roughly into three groups: lipophilic, hydrophilic, and intermediate agents. Ciprofloxacin, norfloxacin, and enoxacin belong to the hydrophilic group. The intermediate group, which includes ofloxacin, AM-833, NY-198, and pefloxacin, achieved higher serum levels after oral administration. Thus, the antibacterial activities of these agents in vivo are thought to reflect their antibacterial activities in vitro and their bioavailability.