The pharmacokinetics and tissue penetration of ceftriaxone after a single intravenous injection of 1,000 mg to 17 patients for antibiotic prophylaxis in thoracic surgery were studied. The patients were scheduled for elective noncardiac thoracic surgery. Adequate levels in serum (higher than or equal to the MIC for 90% of isolates of Staphylococcus aureus, Streptococcus spp., Escherichia coli, Haemophilus influenzae, and Klebsiella pneumoniae) were found for all patients throughout the surgical procedures. Mean maximal (5-min) and final (24-h) ceftriaxone levels in serum were 157 +/- 42 and 8.6 +/- 4.5 mg/liter, respectively. The beta-phase elimination half-life was 8.6 +/- 3 h, the plasma clearance was 18.4 +/- 6.25 ml/min, and the apparent volume of distribution at steady state was 0.21 +/- 0.07 liters/kg. At the time of the thoracotomy, the ceftriaxone concentrations were 13.5 +/- 7.8 micrograms/g in thoracic wall fat and 27 +/- 9 micrograms/g in lung tissue. At the time of closure, the ceftriaxone concentration was 15 +/- 9 micrograms/g in thoracic wall fat. During the different steps of the surgical procedures, 100% of patients had adequate levels in tissue (higher than or equal to the MIC for 90% of isolates of Streptococcus spp., E. coli, H. influenzae, and K. pneumoniae). For S. aureus, 90 to 100% of patients had adequate tissue ceftriaxone levels.