[Pharmacokinetics of antibiotics in inflamed and healthy lung tissue]

The pharmacokinetic profile of antibiotics at the site of antiinfective action is one of the most important determinants of drug response, since it correlates the antimicrobial effect. Up to now, only limited information on the lung tissue pharmacokinetics of antibiotic agents has been available. The aim of in-vivo microdialysis is to measure antibiotic penetration into the extracellular space fluid of normal or pneumonic human lung parenchyma. The lung penetration of cefpirom in elective thoracic surgery and piperacillin in septic thoracic surgery, substances with low protein binding, was measured. Intra-, or postoperatively, respectively, microdialysis probes were inserted into normal or pneumonic lung tissue and into healthy skeletal muscle to obtain reference values. Serum and microdialysis samples were collected at 20-minute intervals for at last 8 hours. The intrapulmonary concentrations of the antibiotics exceeded the minimum inhibitory concentrations (MIC) for most relevant bacteria for 4-6 hours. The procedure was well tolerated by all patients and no adverse events or microdialysis-associated side effects were observed. This microdialysis technique enabled continuous tissue pharmacokinetic measurement of free, unbound anti-infective agents in the lung tissue, even in pneumonia.