The pharmacokinetics of aztreonam and penetration into the bronchial secretions of critically ill patients

The pharmacokinetics of aztreonam were studied in ten critically ill intubated patients with lower respiratory tract infections. Serum and urinary concentrations of the drug and its penetration into bronchial secretions after a 2-g intravenous bolus were measured. Using a two-compartment linear model a terminal half-life of 1.87 + 0.46 h was determined. No interpatient differences were found for half-life values, AUC or volume of distribution, except in the case of one obese patient. The greatest variability was observed in the clearance values, and in particular the extrarenal clearance which ranged from 0.3 to 9.6 1/h. Maximum concentrations in bronchial secretions were reached very quickly in the 2 h after drug administration, with a range of 4.8-18.7 mg/l. No accumulation of aztreonam after repeated doses was detected.