From AUC/MIC to AUCss and Cmin: Optimizing Micafungin Therapy in the Critically Ill through Model-Informed Precision...

Area of Science:

• Pharmacology
• Infectious Diseases
• Critical Care Medicine

Background:

• Micafungin, an echinocandin, is crucial for invasive fungal infections.
• Its pharmacokinetics (PK) in intensive care unit (ICU) patients exhibit significant variability.
• Optimizing micafungin dosing is essential for effective treatment in critically ill populations.

Purpose of the Study:

• To characterize micafungin population PK in ICU patients.
• To identify clinical factors influencing micafungin exposure.
• To evaluate AUCss and Cmin as practical alternatives to AUC/MIC for therapeutic drug monitoring (TDM).

Main Methods:

• Population PK analysis using a two-compartment model with first-order elimination.
• Covariate analysis via stepwise selection to identify influencing factors.
• Receiver operating characteristic (ROC) analysis to assess PK/pharmacodynamic (PD) index performance.

Main Results:

• High interindividual variability in micafungin clearance (59.9%) was observed, with total bilirubin as a significant covariate.
• AUCss and Cmin showed superior predictive performance for microbiological eradication compared to the AUC/MIC ratio (ROC AUC 0.656 and 0.641 vs. 0.579).
• Achieving target AUCss (>90.15 mg·h/L) or Cmin (>1.22 mg/L) correlated significantly with faster fungal eradication.

Conclusions:

• Micafungin exposure is highly variable in critically ill patients, influenced by factors like total bilirubin.
• AUCss and Cmin are promising, MIC-independent metrics for guiding micafungin therapy in ICU settings.
• Further validation of these simplified monitoring strategies may enhance treatment outcomes for invasive fungal infections.