Quinolone are synthetic broad-spectrum antibiotics.

• Quinolones and its derivatives have also been isolated from natural sources, e.g. plants, animals, bacteria, and can act as natural antimicrobials or signalling molecules
• It exerts its antibacterial effect by preventing bacterial DNA from unwinding and duplicating
• The majority of quinolones are fluoroquinolones, which have a fluorine atom attached to the central ring system, typically at the 6-position or C-7 position

Divided into generations, based on their antibacterial spectrum. The earlier generations are generally more narrow spectrum. Most are named with the -oxacin suffix. It includes:

• 1st generation, which are the nonfluorinated drugs. They are rarely used today:
  • Cinoxacin
  • Nalidixic acid, which is a carcinogen
  • Oxolinic acid
  • Piromidic acid
  • Pipemidic acid
  • Rosoxacin
• ​2nd generation:
  • Ciprofloxacin (Enoxin, Cipro)
  • Enoxacin
  • Fleroxacin
  • Lomefloxacin
  • Nadifloxacin
  • Norfloxacin (NOR)
  • Ofloxacin
  • Pefloxacin
  • Rufloxacin
• 3rd generation, which is different from the 1st and 2nd generation, as it is active against streptococci, including:
  • Balofloxacin
  • Grepafloxacin
  • Levofloxacin (Levaquin)
  • Pazufloxacin
  • Sparfloxacin
  • Temafloxacin
  • Tosufloxacin
• 4th generation, which act at DNA gyrase and topoisomerase IV. This dual action slows development of resistance. It includes:
  • Clinafloxacin
  • Gatifloxacin
  • Gemifloxacin
  • Moxifloxacin (Avelox)
  • Sitafloxacin
  • Trovafloxacin
  • Prulifloxacin

• Various Rx have been removed from clinical practice due to severe toxicity issues