[Pharmacokinetic investigations on the penetration of mezlocillin into the pleural fluid].

5 g of mezlocillin were administered by a 30 minute drip infusion to each of ten patients (mean age 59.4 years). Antibiotic concentrations in serum and pleural fluid were assayed microbiologically at regular intervals. The antibiotic concentrations determined 1.5 and 8 hours after beginning the infusion were between 83.9 and 4.0 mg/l in the serum and 53.1 and 6.5 mg/l in the pleural fluid. A comparison of the mean antibiotic concentration found in the pleural secretions (22 mg/l) with the minimal inhibitory concentrations of clinically relevant pathogens shows that mezlocillin covers 69% to 84% of the pathogen spectrum. Mezlocillin can thus be used in the therapy of infectious pleural effusions.