Gatifloxacin is an antibiotic of the fourth-generation fluoroquinolone family, that like other members of that family, inhibits the bacterial enzymes DNA gyrase and topoisomerase IV. Bristol-Myers Squibb introduced Gatifloxacin in 1999 under the proprietary name Tequin for the treatment of respiratory tract infections, having licensed the medication from Kyorin Pharmaceutical Company of Japan. Allergan produces an eye-drop formulation called Zymar. Gatifloxacin is available as tablets and in various aqueous solutions for intravenous therapy.

Norfloxacin is an oral broad-spectrum fluoroquinolone antibacterial agent used in the treatment of urinary tract infections. It is also sometimes used to treat stomach infections.

Levofloxacin is a 3rd generation fluoroquinolone antibiotic, marketed by Ortho-McNeil under the trade name Levaquin in the United States. In Europe, it is marketed by Sanofi-Aventis under the trade name Tavanic, in Chile as Gatigol by Alpes Selection, in India under the trade name Lebact marketed by Nicolas Piramal and in Asia it is marketed by Daiichi under the trade names Cravit and Levox. Levofloxacin was launched in the Japanese market in 1993, and thus has had more than 13 years of testing in efficacy and safety globally. Chemically, levofloxacin is the S-enantiomer (L-isomer) of ofloxacin, and has approximately twice the potency of ofloxacin, because the R+enantiomer (D-isomer) of ofloxacin is essentially inactive. In addition, the S-enantiomer (L-isomer) of ofloxacin, has substantially less toxicity. Like other fluoroquinolines, it works by inhibiting DNA gyrase, an enzyme that negatively supercoils DNA.