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Evaluation of lung tissue and hilar lymph node concentrations of azithromycin
M Cazzola1, C Siniscalchi, A Vinciguerra
1Institute of Pharmacology and Toxicology, Medical School, Second Neapolitan University, Naples, Italy.
Abstract:
Since it is believed that most infections occur in the interstitial fluid, it has been suggested to measure the concentration of antimicrobial agents in pulmonary lymph that reflects the extracellular, extra-blood-vascular milieu in the lung. The aim of this study was to investigate the lung tissue and pulmonary lymph node penetration of azithromycin after 500 mg daily oral administration for three days in patients undergoing open thoracotomy. At the end of the treatment, each subject was assigned for 5 groups of 5 patients each according to thoracotomy time after the last dose (24, 48, 96, 120 and 144 h). Azithromycin was assayed by an agar diffusion method with Sarcina lutea Z114 (DRH) used as the test organism and the Antibiotic Assay Medium 1, pH 8.5 used as the medium. All patients had a detectable concentration of azithromycin in serum 24 h after the last dose (72 h after the first dose); the concentration fell below the detection limit (0.01 mg/l-1) after 96 h (168 h after the first dose). Peak concentrations in lung tissue and lymph nodes were found after 48 h (96 h after the first dose). Tissue and lymph node concentrations of azithromycin were much greater than serum concentrations and these tissue and lymph node concentrations persisted after serum concentrations declined. The concentrations in lung tissue of azithromycin were always higher than corresponding concentrations in hilar lymph nodes.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
This study tracked azithromycin levels in lung tissue and lymph nodes after oral administration. Azithromycin concentrations in lung tissue and lymph nodes were higher and lasted longer than in serum, suggesting good penetration for treating lung infections.
Area of Science:
- Pharmacology
- Infectious Diseases
- Pulmonary Medicine
Background:
- Pulmonary infections are often treated with antibiotics, but their penetration into lung tissues and lymph nodes is not well understood.
- Pulmonary lymph is considered a valuable indicator of antimicrobial agent concentration in the lung's extracellular fluid.
Purpose of the Study:
- To evaluate the penetration and persistence of azithromycin in lung tissue and pulmonary lymph nodes.
- To compare azithromycin concentrations in lung tissue, lymph nodes, and serum after oral administration.
Main Methods:
- A total of 25 patients undergoing open thoracotomy received 500 mg of azithromycin daily for three days.
- Lung tissue, hilar lymph node, and serum samples were collected at various time points (24-144 hours) after the last dose.
- Azithromycin concentrations were determined using an agar diffusion method with Sarcina lutea.
Main Results:
- Detectable azithromycin concentrations were found in serum up to 96 hours post-dose.
- Peak concentrations in lung tissue and lymph nodes were observed at 48 hours and were significantly higher than serum levels.
- Azithromycin concentrations in lung tissue and lymph nodes persisted longer than in serum, with lung tissue concentrations consistently higher than lymph node concentrations.
Conclusions:
- Azithromycin demonstrates substantial penetration into lung tissue and pulmonary lymph nodes following oral administration.
- The sustained concentrations in lung tissue and lymph nodes suggest azithromycin's potential efficacy in treating pulmonary infections.
- Lung tissue appears to achieve higher azithromycin concentrations than hilar lymph nodes.