Prediction of vancomycin pharmacodynamics in children with invasive methicillin-resistant Staphylococcus aureus infections: a Monte Carlo simulation.
BACKGROUND
Due to the emergence of community-associated strains, the prevalence of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections has increased substantially in pediatric patients. A vancomycin AUC(0-24)/MIC index >400 best predicts treatment outcomes for invasive MRSA infection in adults. Data on whether recommended vancomycin doses in children achieve this break point are lacking.


OBJECTIVE
This study aimed to assess the likelihood that currently recommended vancomycin doses in children achieve AUC(0-24)/MIC >400.


METHODS
Vancomycin AUC(0-24)/MIC predictions were conducted across a range of dosages (40-70 mg/kg/d) using a Monte Carlo simulation (n = 5000). AUC(0-24) was calculated as daily dose divided by vancomycin clearance, and daily dose was fixed for a given simulation. Three literature-reported estimates in children were used to define vancomycin clearance and its variance. For the MIC distribution of MRSA isolates, susceptibility data were obtained from the University of California, San Francisco Children's Hospital, San Francisco, California (n = 180; 40% < or =0.5 mg/L; 59% = 1 mg/L; and 1% = 2 mg/L).


RESULTS
Using the recommended empiric dosage of 40 mg/kg/d, 58% to 66% of children were predicted to achieve AUC(0-24)/MIC >400. Increasing the vancomycin dosage to 60 mg/kg/d substantially increased the likelihood (88%-98%) of achieving this pharmacodynamic target. On sensitivity analysis, a dosage of 40 mg/kg/d was more strongly influenced by small changes in MIC compared with 60 mg/kg/d.


CONCLUSIONS
Recommended empiric vancomycin dosing in children (40 mg/kg/d) was not predicted to consistently achieve the pharmacodynamic target of AUC(0-24)/MIC >400 for invasive MRSA infections. A vancomycin dosage of 60 mg/kg/d was predicted to optimize achievement of this target in children.
Frymoyer
Adam
A
Division of Clinical Pharmacology, Department of Medicine, University of California, San Francisco, California 94143-0912, USA. frymoyera@peds.ucf.edu
Hersh
Adam L
AL
Coralic
Zlatan
Z
Benet
Leslie Z
LZ
Joseph Guglielmo
B
B
D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology; D019540:Area Under Curve; D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007223:Infant; D016013:Likelihood Functions; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D009010:Monte Carlo Method; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D014640:Vancomycin / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D014640:Vancomycin
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