Effectiveness of Pharmacokinetic/Pharmacodynamic-Guided Meropenem Treatment in Critically Ill Patients: A Comparative Cohort Study.

BACKGROUND: The proper dosage of antibiotics is a key element in the effective treatment of infection, especially in critically ill patients. This study aimed to evaluate the efficacy of optimized meropenem regimens based on pharmacokinetic/pharmacodynamic criteria in patients admitted to the intensive care unit. METHODS: This observational, naturalistic, retrospective, unicentric cohort study was performed between May 2011 and December 2017. The clinical and bacteriologic responses of 77 control intensive care unit patients receiving meropenem were compared with those of 77 propensity score-balanced patients who received meropenem dose adjusted by therapeutic drug monitoring. The primary end point of clinical response was a reduction at the end of treatment of at least 80% of the maximum procalcitonin (PCT) value recorded during the meropenem treatment. RESULTS: The primary end point was met by 55 patients (71.4%) in the adjusted group compared with 41 (53.3%) patients in the control group (mean difference 18.1%, P = 0.02). Fifty-one patients (66.2%) in the adjusted group required a meropenem dose adjustment, being necessary in 46 of them (90.2%) to decrease the dose. The reduction of PCT was the greatest in the adjusted group compared with the unadjusted group (93% versus 85%, P = 0.004); a greater percentage of patients reached a PCT level < 0.5 ng/mL (63.6% versus 41.6%, P = 0.006), and there was a trend toward an improved bacteriologic response (relative risk = 1.27; 95% confidence interval: 0.92-1.56). There were no differences in early mortality or safety between groups. CONCLUSIONS: Adjustment of meropenem therapy by monitoring is a useful strategy for improving meropenem effectiveness in the treatment of infection in critically ill patients, with no impact on safety.

Evaluation of a non-parametric modelling for meropenem in critically ill patients using Monte Carlo simulation.

PURPOSE: In critically ill patients treated with meropenem, the proposed pharmacokinetics/pharmacodynamics (PK/PD) efficacy index is to keep the free drug concentration 4-5 times above the minimum inhibitory concentration (MIC) of the germ isolated, for 100% of the interval regimen. The objectives were to design a population pharmacokinetics model for meropenem in critically ill patients and to evaluate different dosage schemes that achieve the optimal PK/PD objectives. METHODS: This retrospective, observational, single-centre study included 80 critically ill patients (154 samples) treated with meropenem between May 2011 and December 2017. Patient data, concentrations, treatment and bacteriological variables were collected from electronic medical records. Total and free concentrations of meropenem were modelled in Pmetrics. Monte Carlo simulations were performed to assess the probability of achieving the PK/PD target for different dosage regimens. For patients with available data, the number of patients with a free concentration 4 times higher or lower than the observed MIC for the P. aeruginosa and E. coli was investigated. RESULTS: A one-compartment model with first-order elimination adequately described serum total and free meropenem concentrations. The only variable that significantly influenced the elimination constant of meropenem was the creatinine clearance (CLcr) calculated using the CKD-EPI formula. The highest probability of achieving the pharmacodynamic objective was with 3-h infusion dosage regimens. Sixty percent and 89% of patients attained a free drug concentration 4 times above the MIC for P. aeruginosa and E. coli respectively. CONCLUSIONS: This study proposed different dosing regimens depending on renal clearance strata and the MIC of the germ targeted.