The Quinolones. An Overview of Their Pharmacology

The fluoroquinolones represent a relatively new class of antibiotics with outstanding therapeutic potential, attributable to their broad spectrum of antimicrobial activity and favourable tissue distribution. They are highly active against most Gram-negative pathogens, as well as Staphylococcus aureus and coagulase-negative staphylococci. In addition, the fluoroquinolones have useful pharmacokinetic properties: they are orally active, and their lipophilicity and low degree of plasma protein binding allow for excellent tissue penetration and concentrations, as reflected in their particularly large apparent volumes of distribution. Infections due to aerobic Gram-negative pathogens are considered those most susceptible to the quinolones. Disease indications in which these agents appear to offer the greatest therapeutic advantage over currently available alternatives include the following: complicated urinary tract infections (particularly those caused by Pseudomonas aeruginosa or resistant Gram-negative microorganisms); suspected bacterial gastroenteritis; eradication of Salmonella typhi from the faeces in known carriers; P. aeruginosa-associated respiratory exacerbation in patients with cystic fibrosis; and chronic Gram-negative bacterial osteomyelitis. Direct comparisons of the various quinolones are too limited to date to provide clear therapeutic options. Nevertheless, this class of compounds is likely to play a major role in providing effective oral therapy for conditions that have previously required prolonged parenteral treatment.