Pharmacokinetics of enoxacin and its oxometabolite after multiple oral dosing and penetration into prostatic tissue.

The objective of this study was to determine the concentrations of enoxacin and its oxo-metabolite in human prostatic tissue after multiple oral doses (400 mg bd) in 13 patients. On the first day of treatment, elimination half-lives were 6.8 h for enoxacin and 7.1 h for its metabolite; they were increased on day 4 (10.3 and 13.2 h, respectively). The ratios of drug concentration in prostatic tissue and plasma averaged 2.2 for enoxacin and 1.4 for its metabolite. In conclusion, concentrations of enoxacin achieved within the prostatic tissue were higher than plasma concentrations suggesting that there was an active transport mechanism.