Polymyxin B Intravenous Administration Strategy Guided by Minimum Inhibitory Concentration in Critically Ill Patients
Shengnan Zhang1, Nan Yang1, Ruwei Yang1
1Department of Pharmacy, The Third Xiangya Hospital of Central South University, Changsha, China.
CPT: Pharmacometrics & Systems Pharmacology
|June 19, 2026
Summary
This study optimizes intravenous polymyxin B (PMB) dosing for severe pulmonary infections using physiologically based pharmacokinetic (PBPK) models. It identifies effective regimens and targets for critically ill patients, improving treatment outcomes for drug-resistant gram-negative pneumonia.
Area of Science:
- Pharmacology and Pharmaceutical Sciences
- Infectious Diseases
- Critical Care Medicine
Background:
- Intravenous polymyxin B (PMB) is crucial for treating multidrug-resistant gram-negative bacterial infections.
- However, its efficacy in pulmonary infections is often limited due to suboptimal dosing and penetration into lung tissues.
- Identifying appropriate patient populations and optimal dosing strategies is essential for maximizing therapeutic benefit.
Purpose of the Study:
- To identify critically ill patients suitable for monotherapy with intravenous PMB for severe pulmonary infections.
- To recommend individualized optimal dosing regimens for intravenous PMB based on pharmacokinetic/pharmacodynamic (PK/PD) targets.
- To evaluate the PK/PD targets and their correlation with clinical outcomes.
Main Methods:
- Development and validation of physiologically based pharmacokinetic (PBPK) models using data from preclinical and clinical studies.
- Prediction of PMB concentrations in epithelial lining fluid (ELF) and plasma.
- Monte Carlo simulations to assess various dosing regimens against established PK/PD targets (ELF AUCss,24h/MIC ≥ 50).
Main Results:
- Simulations indicated that specific intravenous PMB regimens (e.g., 100 mg or 1.50 mg/kg q12h) achieved the ELF PK/PD target in over 90% of patients for pathogens with MIC of 1 mg/L.
- A plasma AUCss,24h/MIC threshold of 80.6 was identified, with retrospective analysis showing significantly better outcomes for patients exceeding this level (p=0.038).
- Dosing recommendations varied based on pathogen MIC, suggesting 50 mg q12h for MICs ≤ 0.5 mg/L and adjunctive therapies for MICs ≥ 2 mg/L.
Conclusions:
- PBPK modeling supports 100 mg or 1.50 mg/kg q12h as initial intravenous PMB regimens for critically ill patients with pulmonary infections.
- Individualized dosing adjustments based on MIC and plasma exposure (AUCss,24h/MIC > 80.6) are recommended.
- Therapeutic drug monitoring and consideration of adjunctive nebulization or combination therapy are advised for optimizing treatment outcomes.
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