Penetration of ceftriaxone into human pleural fluid.

The pharmacokinetics of ceftriaxone were studied for seven patients with pleural effusion of various etiologies. All patients received 1 g of antibiotic, administered as an intravenous bolus. The pleural fluid had a high total protein content (6.0 g/dl). Ceftriaxone levels in plasma and in pleural fluid were determined by the agar well diffusion technique. Total and free drug concentrations in pleural fluid reached 7 to 8.7 and 3.8 to 2.3 micrograms/ml, respectively, in 4 to 6 h. The disappearance of the drug from the pleural fluid was very slow. In these patients, therapeutic ceftriaxone levels were present for at least 53 h in pleural fluid.