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Updated: May 7, 2026
Experimental Endocarditis Model of Methicillin Resistant Staphylococcus aureus (MRSA) in Rat
Published on: June 4, 2012
Considerations for higher doses of daptomycin in critically ill patients with methicillin-resistant Staphylococcus
Marco Falcone1, Alessandro Russo, Mario Venditti
1Department of Public Health and Infectious Diseases "Sapienza," Policlinico Umberto I, University of Rome.
Background:
Higher daptomycin doses are advocated for select methicillin-resistant Staphylococcus aureus (MRSA)-related infections, but the probabilities of target attainment (PTA) and toxicity of these doses have not been characterized in critically ill patients.
Methods:
We evaluated the plasma pharmacokinetics (PK) and clinical outcomes of a cohort of critically ill patients treated with daptomycin 6-8 mg/kg/day for primarily Staphylococcus species-related infections. Daptomycin concentrations were measured intensively over the initial 96-hour dosing period. Data were modeled by population PK analyses, and Monte Carlo simulation was used to estimate the probabilities of effect and toxicity with standard and alternate dosing regimens.
Results:
Fifty patients with a mean (SD) age of 69.7 (12.2) years, weight 74.5 (20.3) kg, and creatinine clearance 56.8 (38.2) mL/minute were enrolled with measurements of 12 (2.2) daptomycin samples per patient. Significantly lower daptomycin exposures were observed despite comparable doses in a subset of patients (n = 13) with augmented clearance (CL). No covariates of CL were identified, but this subset was significantly more likely to be in severe sepsis or septic shock, have higher Sequential Organ Failure Assessment scores, and MRSA bacteremia. In-hospital mortality was significantly higher (30.7% vs 10.8%) in patients with augmented daptomycin CL. Use of an empiric fixed dose of 750 mg of daptomycin is predicted to achieve a comparable PTA with a lower probability of toxicity as compared to the use of 10 mg/kg in critically ill patients.
Conclusions:
A reappraisal of current daptomycin dosing recommendations is needed to improve the PTA and reduce toxicity among critically ill patients.
Insights
Higher daptomycin doses for MRSA infections in critically ill patients may not achieve target concentrations and increase toxicity. A fixed 750 mg dose may offer better outcomes than weight-based dosing.
Area of Science:
- Pharmacology
- Critical Care Medicine
- Infectious Diseases
Background:
- Higher daptomycin doses are suggested for select methicillin-resistant Staphylococcus aureus (MRSA) infections.
- However, target attainment probabilities (PTA) and toxicity risks are uncharacterized in critically ill patients.
Purpose of the Study:
- To evaluate daptomycin pharmacokinetics (PK) and clinical outcomes in critically ill patients.
- To assess PTA and toxicity probabilities with different dosing regimens via Monte Carlo simulation.
Main Methods:
- Population PK analysis of daptomycin concentrations in 50 critically ill patients over 96 hours.
- Monte Carlo simulation to predict PTA and toxicity for standard and alternative dosing.
Main Results:
- Critically ill patients with augmented clearance (CL) had lower daptomycin exposure and higher mortality (30.7% vs 10.8%).
- Augmented CL was associated with severe sepsis, higher SOFA scores, and MRSA bacteremia.
- A fixed 750 mg daptomycin dose is predicted to achieve comparable PTA with lower toxicity than 10 mg/kg.
Conclusions:
- Current daptomycin dosing may require reappraisal for critically ill patients.
- Optimizing daptomycin dosing can improve PTA and reduce toxicity in this population.
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