The penetration of macrolides into bronchial secretions.

Macrolides have shown efficacy in the treatment of a large range of respiratory infections. These antibiotics are well tolerated, have a narrow antibacterial spectrum, and excellent diffusion properties. We have studied the penetration into bronchial secretions of three macrolides, erythromycin, josamycin and oleandomycin. The bronchial concentrations of erythromycin reached an average of 1 mg/l 2 h after oral administration of 1 g; they were lower for josamycin (0.52 mg/l) but the ratio between bronchial and simultaneous serum concentrations was similar for both drugs. Bronchial levels of oleandomycin were rapidly higher than the serum levels, reaching 3 to 4 mg/l, a ratio of more than 100%. Other studies on tissue concentrations of erythromycin and josamycin showed local levels of 4 to 6 mg/l, whereas in bronchial secretions the concentrations were identical to those measured in our study. On the whole, the good diffusion of macrolides into respiratory tissues and secretions as well as in-vitro antibacterial activity against most species responsible for respiratory infections confirm their indication in the treatment of these infections.