Utilizing an Opportunistic Clinical Study and Population-Based Pharmacokinetic Models to Identify Rational Empiric Dosing Regimens for Piperacillin-Tazobactam in Critically Ill Patients

Determining an effective dosing regimen for piperacillin-tazobactam in critically ill patients is challenging due to substantial pharmacokinetic variability caused by complex pathophysiological changes. To address this need, a prospective clinical study was conducted, which enrolled 112 critically ill patients and employed an opportunistic sampling strategy. Population modeling and simulation were performed to characterize the pharmacokinetics (PK) and probability of target attainment (PTA) of piperacillin-tazobactam under various dosing regimens. Both piperacillin and tazobactam final models were one-compartment models with zero-order input and first-order elimination. Significant covariates included lean body weight for piperacillin and creatinine clearance along with continuous renal replacement therapy (CRRT) for both drugs. Monte Carlo simulations demonstrated that continuous infusion can achieve higher PTA than intermittent and extended infusions. When considering the minimum inhibitory concentration (MIC) of 16 mg/L for Pseudomonas aeruginosa (a frequently encountered bacterial pathogen among critically ill patients) and a PK/PD target of 100% fT >MIC, continuous infusion of 6 g/day is recommended for critically ill patients with a CLcr