Meropenem Assessment before and after Implementation of a Small-Dose, Short-Interval Standard Dosing Regimen.

Background: Small-dose, short-interval dosing for meropenem has been shown to yield pharmacokinetic and pharmacodynamic properties similar to those associated with traditional dosing of this drug. However, few studies have examined clinical outcomes in the general population.

Objectives: To characterize differences in effects between a small-dose, short-interval dosing regimen for meropenem (500 mg every 6 h) and the traditional regimen (1000 mg every 8 h) on clinical outcomes and costs to the health care system.

Methods: This retrospective cohort study included 194 patients who received the traditional meropenem dosage (July 2006 to August 2008) and 188 patients who received the small-dose, short-interval regimen (December 2008 and October 2009) at a large tertiary care hospital and a community hospital. The primary outcome (clinical success), the secondary outcomes (30-day in-hospital mortality, time to defervescence, duration of therapy, and length of stay), and drug costs were compared between cohorts.

Results: The 2 cohorts did not differ significantly in terms of baseline characteristics. There was no statistically significant difference between the small-dose, short-interval regimen and the traditional dosing regimen in terms of the primary outcome: clinical success was achieved in 83.5% (162/194) and 80.8% (152/188) of the patients, respectively. Likewise, there was no statistically significant difference in any of the secondary outcomes. The average drug cost per patient per visit was $222.23 with small-dose, short-interval dosing and $355.90 with traditional dosing, a significant difference of more than $130 per patient per visit.

Conclusion: The small-dose, short-interval meropenem dosing regimen resulted in clinical outcomes similar to those achieved with the traditional dosing regimen at significantly lower cost.