Evaluation of Meropenem Extended Versus Intermittent Infusion Dosing Protocol in Critically Ill Patients

Extended infusion (EI) administration of β-lactams can improve target attainment in critically ill patients with altered pharmacokinetics/pharmacodynamics. To optimize meropenem dosing in patients with severe sepsis/septic shock, our Antimicrobial Stewardship Program implemented a EI meropenem (EIM) protocol in an 18-bed Medical Intensive Care Unit in March 2014. In this retrospective study, we compared intensive care unit (ICU) mortality and clinical response in patients who received meropenem for ≥72 hours administered per EIM protocol of 1 g over 3 hours every 8 hours versus intermittent infusion (IIM) protocol of 500 mg over 30 minutes every 6 hours. Age, weight, comorbidities, severity of illness, and vasopressor use were comparable between groups (EIM protocol n = 52, IIM protocol n = 96). The IIM protocol group had higher rates of renal dose adjustment at meropenem initiation. Among 56 identified gram-negative (GN) pathogens, 94% had meropenem minimal inhibitory concentration ≤0.25 mg/L. The ICU mortality was lower (19 vs 37%; P = .032) and clinical response was higher (83% vs 46%; P < .01) in the EIM protocol versus IIM protocol group. Total vasopressor days were shorter (2 vs 3 days; P = .038), and white blood cell normalization rate was higher (87% vs 51%; P < .01) in the EIM protocol versus IIM protocol group. There was no difference in days of mechanical ventilation, duration of therapy, and ICU stay. The IIM protocol was also identified as an independent risk factor associated with ICU mortality (hazard ratio: 3.653, 95% confidence interval: 1.689-7.981; P = .001) after adjusting for Sequential Organ Failure Assessment score. In this cohort of patients with severe sepsis/septic shock and highly susceptible GN pathogens, there was improved mortality and clinical response in the EIM protocol group.