PENETRATION OF PEFLOXACIN AND ITS DESMETHYL METABOLITE INTO THE UROEPITHELIUM AFTER A 800-MG SINGLE ORAL DOSE IN HUMAN PATIENTS

Penetration of pefloxacin into the uroepithelium was studied in 20 pat ients (10 men and 10 women) receiving a single oral dose of 800 mg. Sa mples of serum, urine, and uroepithelium were taken 1.8 h (mean) after the dose. Pefloxacin and its active metabolite, norfloxacin, were ass ayed by liquid chromatography, and the microbiologically active compou nds were quantified by a microbiological assay, Both procedures were c orrelated (r > 0.7); nevertheless, slight differences detected in conc entrations depended on the levels of norfloxacin achieved in the biolo gical samples. The serum and tissue concentrations were higher than th e concentration of bactericide (4 mu g . ml(-1)), except in one case. The uroepithelium concentration of pefloxacin was proportional to the serum concentration (r = 0.79). The urinary concentrations ranged from 1.2 mu g . ml(-1) to 82.4 mu g . ml(-1). The mean norfloxacin/pefloxa cin ratios were 3% in serum, 8% in uroepithelium, and 44% in urine. Th e mean uroepithelium/serum concentration ratios were 1 for pefloxacin and 2.3 for norfloxacin. This result shows that, at a time close to th at of the maximum concentration, there is good penetration of pefloxac in and norfloxacin into the uroepithelium.