Pharmacodynamics of antibiotics in the respiratory tree.

For an antibiotic to be active in vivo, the concept of high tissue concentrations at infected sites has been popular for a long time, but has recently been criticised. The measurement of antibiotic tissue levels in humans is restricted by ethical issues, the cost of investigations and doubtful clinical significance. In the respiratory tree (RT), antibiotic concentrations have been studied. It has been shown that the antibiotic concentrations in both the lung tissue and fluids are related to three factors: the frequency of community and severe hospital respiratory infections; the wide prescription of antibiotics in cases of respiratory infections; and the easy access of sampling different areas of the RT. Due to the controversial perception of these studies, new pharmacological approaches have been developed using animal models, in vitro simulation of antibiotic kinetics in human serum and the involvement of pathogens, thus resulting in new pharmacodynamic parameters. This review looks at the concepts in antibiotic concentrations and the pharmacodynamics of the RT.