Clinical and economic benefits of a meropenem dosage strategy based on pharmacodynamic concepts.

PURPOSE The clinical and economic outcomes of a meropenem dosage strategy based on pharmacodynamic concepts are retrospectively reviewed. METHODS The medical records of all patients receiving at least one day of meropenem at a large teaching hospital during 2002 were reviewed. Patients were included if they were clinically evaluable, had no prior successful antibiotic therapy, and received a meropenem dosage appropriate for renal function. Clinical outcomes were evaluated by the rate of response (days to normalization of temperature or lymphocyte count) and success rate. A cost-minimization analysis was performed from the hospital's perspective for level 1, 2, and 3 costs. The average wholesale price of meropenem for 2002 and the cost for one hospital day at our institution were used to calculate economic outcomes. RESULTS Of the 136 patients identified as receiving at least one dose of meropenem, 85 met inclusion criteria, of whom 45 received meropenem 500 mg every six hours and 40 received meropenem 1000 mg every eight hours. No significant differences in demographics, site of infection, meropenem-related length of stay, or rate of response were found. Clinical success rates were similar between groups (p = 0.862). Patients taking the 500-mg regimen received less meropenem during treatment than those in the 1000-mg group (13 g versus 18 g, respectively) (p = 0.012). Median level 1 and 2 costs were significantly lower for the 500-mg regimen (p = 0.009 and p = 0.008, respectively). Level 3 costs were not significantly different. CONCLUSION A pharmacodynamically designed meropenem dosage strategy of 500 mg every six hours yielded similar clinical outcomes to a regimen of 1000 mg every eight hours and reduced the daily drug acquisition costs associated with antibiotic therapy.