[Diffusion of piperacillin into bronchial secretions].

Piperacillin is a ureido-penicillin characterized by the presence of a piperazine group at the position 6 of the beta-lactam ring. This group confers a broader spectrum that includes Pseudomonas. In vitro studies have shown that piperacillin is active against clinical strains recovered from intensive care unit patients with severe lower respiratory tract infections. The purpose of our study was to investigate the usefulness of piperacillin in such patients by evaluating the drug's diffusion into bronchial secretions. A single 4 g dose of piperacillin was given intravenously over three minutes to each of 6 intensive care unit patients. Serum and bronchial secretion samples (obtained through a tracheal intubation or tracheostomy tube) were taken 1/2 hour, 2 h, 4 h and 6 h after the injection to evaluate piperacillin kinetics. Serum piperacillin concentrations were maximal 30 mn after the IV (mean value: 90.6 +/- 23.8 micrograms/ml) and thereafter fell gradually (mean value after 4 hours: 40.4 +/- 27.5 micrograms/ml). Peak concentrations in bronchial secretions were recorded at 2 hours (12.2 +/- 8.5 micrograms/ml); the mean residual value at 6 hours was 4.9 +/- 8.7 micrograms/ml. The diffusion ratio (ratio of bronchial secretion concentration to simultaneous serum concentration) was 15.5% to 24.5%. Our results show that the diffusion of piperacillin into bronchial secretions is outstanding and support the use of this drug in severe respiratory tract infections.