Levels of erythromycin in tear fluid and serum in infants with conjunctivitis.

38 newborns with purulent conjunctivitis were treated with oral erythromycin ethylsuccinate 25 mg/kg every 12 h for 14 days. 3-4 days after initiation of therapy, erythromycin levels in serum and tear fluid were measured 1 and 12 h after the administration of erythromycin. The level of erythromycin in tear fluid was significantly higher than that in serum 1 and 12 h after administration of the antibiotic. On both occasions the concentrations of erythromycin in tear fluid and in serum exceeded the minimum inhibitory concentration (MIC) in vitro for Chlamydia trachomatis.