The pharmacokinetics of ceftazidime during hemodiafiltration in critically ill patients

We studied the pharmacokinetics of ceftazidime in 3 critically ill patients undergoing continuous hemodiafiltration (CHDF). Blood samples were obtained from both the arterial and venous sites of the CHDF system 0, 1, 2, 4, 6, and 12 h after the start of ceftazidime administration. Pharmacokinetic variables were calculated by fitting individual concentration-time curves to a two-compartment open model. The elimination phase half-life was 6.86 h, and the total elimination rate constant was 0.17 h(-1). Six hours after the start of administration, the ceftazidime concentration in the arterial site decreased from the peak level of 77.5+/-31.4 (mean+/-standard deviation [SD]) microg/ml to 26.2+/-2.5 microg/ml. The ceftazidime concentration examined in 2 cases decreased to 14.7+/-5.8 microg/ml after 12 h. The results suggested that ceftazidime should be administered at 1 g/day in patients with severe infection during CHDF.