The penetration of erythromycin into Waldeyer's ring--tonsil and adenoid tissue.

Erythromycin ethylsuccinate was given orally (30-60 mg/kg/day) to 72 otherwise healthy children for different intervals before adenoidectomy. The concentration of erythromycin was assessed in homogenized tissue, in whole blood and in plasma, making it possible to calculate blood-free tissue levels. The tissue levels (1.5-2.0 mg/l) were the same as the plasma levels. Six patients with chronic tonsillitis were given 1000 mg erythromycin ethylsuccinate via a gastric tube, and tonsillectomy à froid was performed three to five hours later. This unusual mode of administration was chosen to avoid tonsil surface contamination, which might cause artificially high values. The concentration of erythromycin was assessed as described above. The levels of erythromycin in the tonsil tissue were the same as the concomitant plasma levels. Erythromycin has been shown to penetrate into adenoid and tonsil tissue and to attain levels similar to the simultaneous plasma levels. It may be inferred from this study that erythromycin penetrates into other lymphatic localities to the same degree.