Overview of the Meropenem Yearly Susceptibility Test Information Collection (1997–2004)

Comparing outcomes of meropenem administration strategies based on pharmacokinetic and pharmacodynamic principles: a qualitative systematic review

OBJECTIVE

To systematically review evidence comparing traditional and alternative dosing strategies for meropenem, based on clinical and pharmacoeconomic outcomes.

DATA SOURCES

MEDLINE (1950-September 2009), EMBASE (1980-September 2009), and International Pharmaceutical Abstracts (1970-September 2009) were searched, using the terms meropenem, carbapenems, pharmacodynamics, and pharmacokinetics. Reference citations from publications identified were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Articles discussing administration of meropenem to adults with normal renal function and comparing at least 2 regimens, 1 of which included the manufacturer-recommended regimen of 0.5 g or 1 g every 8 hours infused over 30 minutes, with clinical, pharmacodynamic, or pharmacoeconomic endpoints, were included. The pharmacodynamic endpoint of interest was percent time that the unbound drug concentration exceeded the minimal inhibitory concentration for a bacterial pathogen.

DATA SYNTHESIS

Sixteen studies were reviewed, which included 13 pharmacokinetic and dynamic assessments using Monte Carlo simulations, 5 clinical evaluations, and 3 pharmacoeconomic appraisals. Data on clinical and economic outcomes are largely nonrandomized retrospective analyses and case reports. Meropenem via intermittent prolonged infusion potentially increases the likelihood of achieving pharmacodynamic targets. However, a strong link with improved clinical outcomes is lacking. Smaller doses with shorter intervals appear to provide pharmacodynamic target attainment rates and clinical outcomes similar to those with traditional dosing, with potential pharmacoeconomic benefits. Meropenem via continuous infusion appears to increase the likelihood of achieving pharmacodynamic targets, compared with intermittent infusions. The sparsity of clinical evidence supporting this practice limits its broad application to practice. No studies have formally examined adverse effects with alternative dosing regimens.

CONCLUSIONS

Meropenem alternative dosing strategies provide similar pharmacodynamic target attainment rates compared with traditional dosing strategies. Small doses with shorter interval dosing provide additional pharmacoeconomic benefits and similar clinical outcomes. Alternative dosing strategies for meropenem were largely studied in healthy subjects; individuals with pharmacokinetic parameters that differ significantly may be ideal subjects for empiric dose modification.

Activity of meropenem as serine carbapenemases evolve in US Medical Centers: monitoring report from the MYSTIC Program (2006)

The Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Surveillance Program was designed to monitor the antimicrobial potency and spectrum of meropenem, and selected broad-spectrum comparison agents against pathogens from hospitalized patients. In the 2006 (year 8 of the study) United States sample, a total of 2841 isolates (94.7% compliance) including 641 Escherichia coli, 619 Klebsiella spp., 606 Pseudomonas aeruginosa, 456 oxacillin-susceptible Staphylococcus aureus, 300 streptococci, 149 Enterococcus faecalis, and 70 Gram-positive anaerobic organisms were tested by reference broth microdilution or agar dilution susceptibility methods. The carbapenems, especially meropenem, consistently demonstrated the lowest resistance rates against Enterobacteriaceae strains, and the fluoroquinolones had the highest and increasing resistance rates. The presence of qnr-mediated fluoroquinolone resistance was investigated using polymerase chain reaction methods but was only observed at very low levels (2.1%) and was not clonally associated. Confirmed extended-spectrum beta-lactamase rates for E. coli and Klebsiella spp. were only 4.8% and 5.0%, respectively, with mobile AmpC (CMY-2 and FOX-5) enzymes shown in 13 additional Enterobacteriaceae isolates. Clonally related KPC-type serine carbapenemase production (57 strains, 9.5%) was observed at a rate 2-fold greater than the prior year among Klebsiella spp. isolates, primarily from 1 geographic region (Middle Atlantic States). These MYSTIC Program (2006) results demonstrate the continued need to monitor the carbapenem class potency and spectrum of activity against Enterobacteriaceae as well as P. aeruginosa because of the documented presence of serine carbapenemases and rare incidence of metallo-beta-lactamases that may further compromise their activity and that of other beta-lactam agents.