The fluoroquinolone antimicrobials: structure, antimicrobial activity, pharmacokinetics, clinical use in domestic animals and toxicity.

Fluoroquinolones form a promising family of new bactericidal antimicrobials. Enrofloxacin (Baytril) is the first antibacterial of this family to be available to veterinary medicine. They share a wide spectrum of antimicrobial activity, a large volume of distribution and are active at very low concentrations. Their target site for bactericidal action is the type II topoisomerase (E.C. 5.99.1.3.). The gastrointestinal absorption in mammals is rapid and substantial, the duration of action is long and the excretion mainly through the kidney. Their adverse effects are not severe when compared to the beneficial features fluoroquinolones exhibit. The target tissues for adverse effects are: the juvenile cartilage, central nervous system, urinary tract and digestive tract. In the USA, approved use is thus far limited to dogs; approval for use in food-animals is currently being sought for several fluoroquinolones. Published clinical trials as well as unpublished data from the author's laboratories are reviewed for dogs, cats, pigs, cattle and poultry.