Patients who received ceftazidime-avibactam as part of their clinical care were consented. EMR data was collected as well as PK sampling around their dosing to include the following samples immediately pre-dose, then at the following times thereafter: 1, 2, 4, 6, and 8 hours. Blood samples were collected in lithium-heparin tubes from a central venous catheter that is not being used for the continuous venovenous hemodiafiltration. The tubes were centrifuged at 2500 rpm for 10 minutes within 1 hour from collection and the samples will be frozen at 80°C. The total concentrations of ceftazidime and avibactam were determined simultaneously from plasma by using a validated HPLC-tandem MS assay. Noncompartmental pharmacokinetics were calculated using the linear-up and logarithmic-down trapezoidal method, based on the assumption of first-order elimination.
