Besifloxacin (INN/USAN) is a fourth-generation fluoroquinolone antibiotic. The marketed compound is Besifloxacin hydrochloride. It was developed by SSP Co. Ltd., Japan, and designated SS734. SSP licensed U.S. and European rights to SS734 for ophthalmic use to InSite Vision Incorporated in 2000. InSite Vision developed an eye drop formulation (ISV-403) and conducted preliminary clinical trials before selling the product and all rights to Bausch & Lomb in 2003. Besifloxacin is indicated in the treatment of bacterial conjunctivitis caused by sensitive germs, as well as in the prevention of infectious complications in patients undergoing laser therapy for the treatment of cataracts. Besifloxacin inhibits bacterial DNA gyrase and topoisomerase IV and has a broad spectrum of bactericidal activity against strains commonly isolated from patients with bacterial conjunctivitis. In addition, some exploratory in vitro data suggest that Besifloxacin inhibits cytokine formation in human corneal epithelial cells and monocytes, but the relevance of this finding to therapeutic efficacy is unknown.

Ofloxacin is one of a new generation of fluorinated quinolones structurally related to nalidixic acid, primary mechanism of action is inhibition of bacterial DNA gyrase. It is an orally administered broad spectrum antibacterial drug active against most Gram-negative bacteria, many Gram-positive bacteria and some anaerobes. Clinical trials to date have demonstrated the efficacy of ofloxacin in the treatment of lower respiratory tract infections, urinary tract infections, and sexually transmitted diseases. Adverse effects to ofloxacin are usually mild and include gastrointestinal, central nervous system, and hypersensitivity reactions. Also available in solution for treatment of otic and ophthalmic bacterial infections.

Ciprofloxacin (1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid) is the synthetic antimicrobial agent for oral or intravenous administration. Ciprofloxacin is a member of the fluoroquinolone class of antibacterial agents. The bactericidal action of ciprofloxacin results from inhibition of the enzymes topoisomerase II (DNA gyrase) and topoisomerase IV (both Type II topoisomerases), which are required for bacterial DNA replication, transcription, repair, and recombination. Ciprofloxacin is used to treat a wide variety of infections, including infections of bones and joints, endocarditis, gastroenteritis, malignant otitis externa, respiratory tract infections, cellulitis, urinary tract infections, prostatitis, anthrax, and chancroid. In the United States, ciprofloxacin is pregnancy category C. This category includes drugs for which no adequate and well-controlled studies in human pregnancy exist, and for which animal studies have suggested the potential for harm to the fetus, but potential benefits may warrant use of the drug in pregnant women despite potential risks. Fluoroquinolones have been reported as present in a mother's milk and thus passed on to the nursing child. Oral and intravenous ciprofloxacin is approved by the FDA for use in children for only two indications due to the risk of permanent injury to the musculoskeletal system: Inhalational anthrax (postexposure) and Complicated urinary tract infections and pyelonephritis due to Escherichia coli.

Coumermycin is from the aminocoumarin class of antibiotic compounds which acts by inhibiting DNA gyrase. Coumermycin is effective against gram-positive bacteria, but not gram-negative bacteria. Coumermycin its derivatives have been studied since the 1950's as potential antibiotic. However, it has seen little to no clinical development because of its low water solubility, toxicity profile, and ineffectiveness against gram-negative bacteria.

Gepotidacin (formerly GSK2140944) is a novel, first-in-class, triazaacenaphthylene antibacterial that selectively inhibits bacterial DNA gyrase and topoisomerase IV by a unique mechanism, one that is not utilized by any currently approved human therapeutic agent. As a consequence of its novel mode of action, gepotidacin is active in vitro against target pathogens carrying resistance determinants to established antibacterials, including fluoroquinolones. Gepotidacin has demonstrated in vitro activity against key pathogens, including drug-resistant strains, associated with a range of conventional and biothreat infections. GlaxoSmithKline is developing Gepotidacin for the treatment of gonorrhoea and skin and soft tissue infections.

Fandofloxacin is a difluoroquinolone derivative. This compound possesses an antibacterial spectrum comparable to those of rufloxacin and ciprofloxacin in vivo. Fandofloxacin showed a rapid and nearly complete absorption, and a long residence time in the body. Because it has been reported that the in vivo antibacterial activity of Fandofloxacin is comparable or superior to other quinolones, despite the fact that its in vitro activity is significantly lower than that of the other compounds, the pharmacokinetics of this antibiotic may be responsible, at least in part, for the enhanced in vivo antibacterial activity of Fandofloxacin. Fandofloxacin is an inhibitor of bacterial DNA gyrase. The toxicities and adverse effects of Fandofloxacin observed in various toxicology studies and clinical trials were less than those of commercially available drugs. It has been in phase II clinical trial for the treatment of Urinary tract infections. However, this research has been discontinued in 2008.

Difloxacin is an aryl fluoroquinolone derivative. The primary bacterial target of fluoroquinolones is the enzyme deoxyribonucleic acid gyrase. Difloxacin is very potent against a broad spectrum of bacteria including aerobic ana anaerobic gram-positive and gram-negative oragnisms. DICURAL® (difloxacin hydrochloride) TABLETS are indicated for the management of diseases in dogs associated with bacteria susceptible to difloxacin.

Ozenoxacin is an experimental quinolone antibiotic being developed for the treatment of impetigo and other dermatological bacterial infections. Ozenoxacin is active against some bacteria that have developed resistance to currently used quinolone and fluoroquinolone antibiotics. In two phase 3 studies, Ozenoxacin cream, 1%, applied topically twice daily for 5 days vs. placebo, demonstrated superiority on both clinical and bacteriological endpoints, according to the release. Superior bacteriological cure of Ozenoxacin compared to placebo was demonstrated as early as day 4. In both adults and a pediatric population aged 2 months and older, Ozenoxacin treatment was reported to be safe and well tolerated.

Lomefloxacin hydrochloride (marketed under the following brand names in English speaking countries Maxaquin, Okacyn, Uniquin) is a fluoroquinolone antibiotic used to treat bacterial infections. It is used to treat chronic bronchitis, as well as complicated and uncomplicated urinary tract infections. It is also used as a prophylactic or preventative treatment to prevent urinary tract infections in patients undergoing transrectal or transurethral surgical procedures. Flouroquinolones such as lomefloxacin possess excellent activity against gram-negative aerobic bacteria such as E.coli and Neisseria gonorrhoea as well as gram-positive bacteria including S. pneumoniae and Staphylococcus aureus. They also posses effective activity against shigella, salmonella, campylobacter, gonococcal organisms, and multi drug resistant pseudomonas and enterobacter. Lomefloxacin is a bactericidal fluoroquinolone agent with activity against a wide range of gram-negative and gram-positive organisms. The bactericidal action of lomefloxacin results from interference with the activity of the bacterial enzymes DNA gyrase and topoisomerase IV, which are needed for the transcription and replication of bacterial DNA. DNA gyrase appears to be the primary quinolone target for gram-negative bacteria. Topoisomerase IV appears to be the preferential target in gram-positive organisms. Interference with these two topoisomerases results in strand breakage of the bacterial chromosome, supercoiling, and resealing. As a result DNA replication and transcription is inhibited.

Temafloxacin (marketed by Abbott Laboratories as Omniflox) is almost completely absorbed from the gastrointestinal tract, with an absolute bioavailability of approximately 93% and is not greatly affected by food. The time to reach peak concentrations ranges between 2 and 3 hours. In addition to the broad spectrum of activity all fluoroquinolones have against gram-negative pathogens, temafloxacin has improved antimicrobial activity against gram-positive aerobic cocci, intracellular microorganisms, and anaerobes. The bactericidal action of temafloxacin results from interference with the activity of the bacterial enzymes DNA gyrase. Omniflox was approved to treat lower respiratory tract infections, genital and urinary infections like prostatitis, and skin infections in the U.S. by the Food and Drug Administration in January 1992. Severe adverse reactions, including allergic reactions and hemolytic anemia, developed in about fifty patients during the first four months of its use, leading to three patient deaths. Abbott withdrew the drug from sale in June 1992.