Serum, sputum and bronchial concentrations of erythromycin in chronic bronchitis after single and multiple treatments with either propionate-N-acetylcysteinate or stearate erythromycin.

Serum and bronchial concentrations of erythromycin were determined in 30 chronic bronchitic patients during an exacerbation phase of bacterial infections. The levels were measured after single and multiple oral treatments with erythromycin-propionate-N-acetylcysteinate (EPAC) or erythromycin stearate (ES) in a double-blind design. EPAC showed higher and longer-lasting erythromycin levels in serum, sputum and pure bronchial mucus than ES. It is believed that EPAC is better absorbed because of its greater stability in the gastrointestinal juices. Higher concentrations in bronchial secretions not always depend on the blood levels. It seems to be possible that the N-acetylcysteine moiety in the molecule of EPAC drug can facilitate antibiotic penetration because of its mucolytic activity. The clinical response (disappearance of fever, clearance of bacterial pathogens from sputum, reduction of quantity and viscosity of sputum) also occurred faster in the EPAC than in the ES group.