Pharmacokinetics of short versus extended infusion meropenem dosing in critically ill patients: A pilot study

Objective: To test whether a prolonged 3-hour infusion of meropenem 500mg achieves an equivalent proportion of time above the minimal inhibitory concentration (MIC) ( TMIC) to that of meropenem 1000mg given over 30 minutes. Design, setting and participants: A randomised crossover study in 10 critically ill patients. Method: We administered meropenem as a 1000mg, 30-minute infusion or as a 500mg, 3-hour infusion. We determined serial plasma concentrations for each dosing episode and performed comparisons of TMIC at different MICs. Outcome measures: The percentage of time that meropenem was above its MIC. Results: For low MICs (=2 mg/L), both regimens attained a TMIC >40 in all patients. For an MIC of 4mg/L, this target was attained in all but one patient, but with an MIC of 8mg/L, three patients in each group had a TMIC