ABSTRACT
Levofloxacin (Levaquin, Iquix, Quixin) is a fluoroquinolone that is the optical S-(–) isomer of ofloxacin. It was originally developed by the Daiichi Seiyaku Pharmaceutical Co. Ltd. in Japan. Its chemical formula is (–)-(S)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido [1,2,3-de] [1,4]benzoxazine-6-carboxylic acid hemihydrate (Figure 104.1), and it has a molecular weight of 370 daltons. Ofloxacin is a racemic mixture of two optical isomers, but the S-isomer has antibacterial activity 32- to 128-fold greater than that of the R-isomer, and thus most of the antibacterial activity of ofloxacin is due to the S-isomer, which constitutes levofloxacin. Levofloxacin, like ofloxacin and other fluoroquinolones, is an inhibitor of the bacterial type II topoisomerases DNA gyrase and DNA topoisomerase IV. Levofloxacin was developed to take advantage of its increased antibacterial potency and a potentially improved toxicity profile (Davis and Bryson, 1994; Inage et al., 1992; Tanaka et al., 1992; Une et al., 1988). Structure of levofloxacin. The arrow points to the asymmetric carbon atom that results in two possible stereoisomers; ofloxacin is a racemic mixture of both stereo-isomers, and levofloxacin is the single S stereoisomer. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315152110/08d8042d-9481-4a8d-8c27-9bd589f6de6b/content/fig104_1.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
