Concentrations of erythromycin in serum and tonsil: comparison of the estolate and ethyl succinate suspensions.

Concentrations of erythromycin were measured in serum and tonsil from children who had received either the estolate or ethyl succinate suspension before surgery. The in vitro assay measured total erythromycin activity against a group A beta hemolytic streptococcus. Levels of erythromycin in serum and tonsil after single and multiple doses of the estolate were significantly higher than those after administration of the ethyl succinate. The therapeutic implications of these findings are unknown.