Concentrations of moxifloxacin in plasma and urine, and penetration into prostatic fluid and ejaculate, following single oral administration of 400 mg to healthy volunteers.

The spectrum of chronic bacterial prostatitis (CBP) comprises Gram-negative, Gram-positive and atypical pathogens. Because of its broad spectrum of activity, moxifloxacin might be a suitable antibiotic for the treatment of CBP. In this pharmacokinetic study, plasma concentrations and the penetration of moxifloxacin into prostatic fluid and ejaculate were investigated. Twelve healthy male volunteers received a single oral dose of 400mg moxifloxacin and at the same time received 3.24 g of iohexol intravenously to assess urinary contamination of prostatic fluid and ejaculate. Plasma concentrations were determined at 0, 0.5, 1, 2, 3 and 4h and prostatic fluid and ejaculate (mean+/-standard deviation (S.D.)) were determined at 3.5+/-0.4h and 3.6+/-0.4h, respectively, following administration of drugs. Urinary concentrations were determined in the urine collected from 0-4.5h. Concentrations of moxifloxacin and iohexol in plasma, secretions and urine were determined by high-performance liquid chromatography. The mean+/-S.D. peak plasma concentration of moxifloxacin was 2.8+/-0.5 mg/L observed after 1.6+/-0.9h. In prostatic fluid, the concentration of moxifloxacin was 3.8+/-1.2 mg/L and the prostatic fluid/plasma ratio was 1.6+/-0.5. In ejaculate, the concentration was 2.5+/-0.7 mg/L and the ejaculate/plasma ratio was 1.0+/-0.2. Moxifloxacin concentrations in prostatic fluid were ca. 60% (P<0.05) higher than in plasma and concentrations in ejaculate were approximately the same as in plasma. Therefore, moxifloxacin might be a good alternative for the treatment of CBP, but further studies are warranted to establish this indication.