XX is a fluoroquinolone antibacterial agent, structurally related to nalidixic acid. Due to it's relatively poor oral bioavailability, its clinical use is limited to the treatment of urinary tract infections and uncomplicated gonorrhea. XX is also approved for use as an ophthalmic solution for bacterial conjunctivitis. It has the shortest half-life of all currently available fluoroquinolones. It was initially approved for systemic use by the FDA in October 1986. XX is bactericidal via its effects on DNA gyrase, an enzyme responsible for counteracting the excessive supercoiling of DNA during replication or transcription. Although human cells do not contain DNA gyrase, they do contain a topoisomerase enzyme that functions in the same manner. This mammalian enzyme is not affected by bactericidal concentrations of quinolones. XX is unclear how inhibition of DNA gyrase leads to bacterial cell death. Both rapid and slow growing organisms are inhibited by fluoroquinolones. |