Disposition of roxithromycin in the epididymis after repeated oral administration

The epididymal penetration of roxithromycin was studied in order to evaluate the drug for use in the treatment of epididymo-orchitis. Seventeen patients hospitalized for surgery as part of treatment for prostatic adenoma or prostatic cancer were premedicated orally with roxithromycin 150 mg bd for three days followed by 150 mg pre-operatively (3 h before surgical incision). Roxithromycin concentrations in serum and epididymis were determined by microbiological assay. The mean epididymal concentrations were 6.48 +/- 4.88 and 5.98 +/- 3.92 mg/kg for left and right epididymis respectively and the corresponding mean tissue/serum ratios 0.88 +/- 0.57 and 0.84 +/- 0.53. The wide intersubject variation in the concentration of roxithromycin found in serum and tissue is commonly seen with other macrolide antibiotics. The concentrations observed in this study in serum and tissue were greater than the MIC90s for Chlamydia trachomatis (0.25 to 1 mg/L), and Ureaplasma urealyticum (0.5 mg/L).