The penetration of erythromycin into the middle ear.

The penetration of erythromycin was studied in 108 cases of secretory otitis media. Erythromycin ethylsuccinate was given orally in a dosage of 30-60 mg/kg/day and samples of middle ear effusion were obtained at different intervals. The concentration of erythromycin in the middle ear effusions reached the plasma level (1.1-1.2 mg/l) after 26 hours. The plateau levels were maintained during the steady state. Elimination was slow; 14 hours after the last dose of a ten-day treatment, the concentration of erythromycin in the middle ear effusions was still as high as 0.9 mg/l, compared to 0.2 mg/l in plasma. The concentration of erythromycin in the middle ear effusions surpassed the MICs of most respiratory pathogens. Erythromycin can thus be regarded as a suitable drug in the treatment of otitis media. Furthermore, since the respiratory mucosa reacts in a uniform manner to an inflammatory stimulus, the result of this penetration study is valid for inflammatory diseases in any area lined with respiratory epithelium.