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Penetration of erythromycin in respiratory tract infections
Abstract:
Successful treatment of respiratory tract infections with erythromycin may depend upon adequate penetration of the drug to the site of infection. The delivery of antibiotics into respiratory tract secretions is a simple passive diffusion process along a concentration gradient according to Fick's principle. A number of other factors including physicochemical characteristics of the drug and host defence mechanisms may further modify the tissue penetration. A common feature of penetration studies in respiratory tract infections is the wide range of results. This is due to the numerous variables involved in this kind of study. However, the studies performed at steady state, and after oral administration of erythromycin, show a rapid increase in drug concentrations in adenoid and tonsillar tissue homogenates and sustained levels equal to or higher than in serum. In secretions of the middle ear, paranasal sinuses and bronchiae the penetration and elimination of erythromycin is much slower. The drug levels were equal to--or in some cases even higher than--steady state serum concentrations. Fluctuations, however, were less pronounced. In lung tissue homogenates erythromycin concentrations higher than the serum levels have generally been found. In respiratory tract secretions and tissues the penetration of erythromycin is good. Sufficient levels are reached to inhibit in vitro the growth of most common pathogens involved in respiratory tract infections with the exception of some strains of Haemophilus influenzae.
Insights
Erythromycin effectively penetrates respiratory tissues and secretions, reaching concentrations sufficient to inhibit most common bacterial pathogens. However, penetration into certain sites like the middle ear and sinuses is slower, with some Haemophilus influenzae strains showing resistance.
Area of Science:
- Pharmacology
- Infectious Diseases
- Respiratory Medicine
Background:
- Respiratory tract infections (RTIs) require effective antibiotic penetration to the site of infection for successful treatment.
- Erythromycin's efficacy in RTIs may be linked to its ability to reach and maintain therapeutic concentrations in respiratory tissues and secretions.
- Antibiotic delivery into secretions follows Fick's principle of passive diffusion, influenced by drug properties and host factors.
Purpose of the Study:
- To evaluate the penetration and concentration of erythromycin in various respiratory tract tissues and secretions.
- To determine if erythromycin concentrations achieve levels adequate for inhibiting common RTI pathogens.
- To identify factors influencing erythromycin penetration and elimination in the respiratory tract.
Main Methods:
- Review of studies on erythromycin penetration into respiratory tissues and secretions after oral administration.
- Analysis of drug concentrations in adenoid, tonsillar, lung tissues, and secretions from middle ear, paranasal sinuses, and bronchi.
- Comparison of drug levels in tissues and secretions with serum concentrations under steady-state conditions.
Main Results:
- Erythromycin demonstrated rapid penetration and sustained concentrations in adenoid and tonsillar tissues, often exceeding serum levels.
- Slower penetration and elimination were observed in middle ear, paranasal sinus, and bronchial secretions, with levels comparable to or higher than serum.
- Lung tissue homogenates generally showed erythromycin concentrations higher than serum levels.
- In vitro studies indicated that erythromycin effectively inhibited most common RTI pathogens, except for some Haemophilus influenzae strains.
Conclusions:
- Erythromycin exhibits good penetration into respiratory tract secretions and tissues, achieving potentially therapeutic concentrations.
- While generally effective, the slower penetration into certain sites and resistance in some H. influenzae strains warrant consideration.
- Achieving adequate drug levels at the infection site is crucial for successful erythromycin treatment of RTIs.