Pharmacokinetics and pharmacodynamics of the new fluoroquinolones: focus on respiratory infections.

High occurrence of penicillin-resistant and multidrug-resistant Streptococcus pneumoniae and reports of resistance with Haemophilus influenzae and Moraxella catarrhalis are influencing the empiric treatment of community-acquired respiratory infections and allowing the new fluoroquinolones to serve as important treatment alternatives. Recent analysis of the pharmacokinetic and pharmacodynamic properties of the new fluoroquinolones (gatifloxacin, gemifloxacin, levofloxacin and moxifloxacin) have shown high bioavailability (> or = 70%) and long serum half-lives (> or = 7 h), allowing for once-daily dosing. They concentrate in respiratory tract tissues and fluids at levels that exceed serum concentrations. Concentration-dependant killing is evident and the pharmacodynamic parameters that best correlate with bacteriological eradication, clinical efficacy and minimization of resistance have now been identified. The new fluoroquinolones display excellent pharmacokinetic and pharmacodynamic properties against community-acquired respiratory pathogens, making them ideal agents for the empirical treatment of community-acquired respiratory infections.