Plasma and saliva concentrations for a new formulation of erythromycin stearate.

Erythromycin saliva and plasma concentrations were determined in 10 subjects after the first and fourth doses of a new formulation of erythromycin stearate ('Erythrocin'), 500 mg 8-hourly, taken immediately before food. Consistent absorption occurred and the steady state plasma levels compared favourably with the minimal inhibitory concentrations of erythromycin for common respiratory pathogens. There was a significant positive correlation between steady state saliva and plasma levels.