Intrapulmonary penetration studies in healthy adult subjects are commonly conducted as a phase I clinical trial to assess plasma and epithelial lining fluid concentrations of new antibacterial drug candidates.

In recent years, a significant number of intrapulmonary penetration studies have been conducted with β-lactam agents, with or without β-lactamase inhibitors.

The number of intrapulmonary penetration studies of newer agents in critically ill patients are limited, however they have demonstrated greater variability in extent and consistency in epithelial lining fluid penetration compared with healthy subjects.

Pharmacokinetic/pharmacodynamic analysis of plasma and intrapulmonary concentration-time data from preclinical animal models, healthy subjects, and critically ill patients has provided support for evaluating optimal dosing of antibacterial agents for the treatment of pneumonia.