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Relevance of antibiotic tissue penetration in treating respiratory tract infections
1Department of Clinical Pharmacology, F. Hoffmann-La Roche Ltd., Basel, Switzerland.
Abstract:
The majority of bacterial respiratory tract infections are caused by streptococci, Haemophilus spp. and Moraxella catarrhalis. These pathogens are located extracellularly. In logical consequence, the bactericidal action of the antimicrobial is required in these loci. To define the reasonable dosing regimen for effective eradication without creating unnecessary toxic potential we need to know (1) the distribution principles and kinetics, and (2) the correct correlation between concentration profiles in extracellular fluid (ECF) and blood. According to the permeability of the vascular capillaries unbound drug concentrations in plasma and ECF are in a dynamic equilibrium. Thus, for the beta-lactam antibiotics therapeutic efficacy is predictable by maintaining the free drug concentration above the bacterial minimum inhibitory concentration. Tissue homogenate data can only be useful if correctly interpreted by correcting for the partitioning between the tissue components.
Insights
Understanding antimicrobial distribution in extracellular fluid (ECF) is key for treating respiratory infections. Maintaining drug concentrations above bacterial minimum inhibitory concentration in ECF ensures effective eradication with beta-lactam antibiotics.
Area of Science:
- Pharmacology
- Microbiology
- Infectious Diseases
Background:
- Bacterial respiratory tract infections are frequently caused by extracellular pathogens like streptococci, Haemophilus spp., and Moraxella catarrhalis.
- Effective antimicrobial treatment requires bactericidal action at the site of infection, necessitating understanding drug distribution and kinetics.
- Extracellular pathogens require antimicrobials to act in the extracellular fluid (ECF) for eradication.
Purpose of the Study:
- To define optimal dosing regimens for effective eradication of respiratory pathogens.
- To understand the distribution principles and kinetics of antimicrobials in relation to ECF and blood.
- To establish the correlation between drug concentrations in ECF and blood for predicting therapeutic efficacy.
Main Methods:
- Analysis of drug distribution principles and kinetics.
- Correlation of drug concentration profiles in extracellular fluid (ECF) and blood.
- Interpretation of tissue homogenate data by correcting for partitioning.
Main Results:
- Unbound drug concentrations in plasma and ECF are in dynamic equilibrium due to vascular capillary permeability.
- Therapeutic efficacy of beta-lactam antibiotics is predictable by maintaining free drug concentration above the minimum inhibitory concentration (MIC).
- Tissue homogenate data requires correction for partitioning to be accurately interpreted.
Conclusions:
- Accurate dosing regimens for respiratory tract infections depend on understanding antimicrobial distribution in ECF.
- Maintaining free drug concentrations above the MIC in ECF is crucial for effective beta-lactam antibiotic therapy.
- Correct interpretation of tissue data is essential for optimizing antimicrobial dosing strategies.