Penetration of ciprofloxacin into prostatic fluid, ejaculate and seminal fluid in volunteers after an oral dose of 750 mg.

To evaluate an effective dose for the treatment of bacterial prostatitis the concentrations of ciprofloxacin were measured in prostatic fluid, ejaculate and the cell-free seminal fluid of 15 healthy volunteers who received an oral dose of 750 mg. ciprofloxacin while in a fasting state. Venous blood samples were taken in all subjects at 1, 2, 3 and 4 hours. In 6 subjects blood samples were also taken after 8 and 12 hours. Urine was collected in all subjects during 0 to 4 hours and in the 6 subjects also during 4 to 8 hours and 8 to 12 hours. Prostatic fluid could be obtained in 10 subjects by prostatic massage 4 hours after drug intake. So as not to contaminate the urethra with ciprofloxacin the subjects were not allowed to void until 4 hours after drug intake. Iopamidol (3.162 gm.), a renal contrast agent, was administered intravenously concomitantly with oral ciprofloxacin intake. After 8 hours iohexol (3.235 gm.) was administered intravenously. These agents were measured in prostatic fluid, ejaculate and seminal fluid to assess the contamination of those fluids by urine. All drug measurements were done by high pressure liquid chromatography. The median plasma concentrations of ciprofloxacin were 2.1 mg./l. at 1 hour (maximum concentration), 0.9 mg./l. at 4 hours and 0.2 mg./l. at 12 hours. The median concentration in prostatic fluid was 0.23 mg./l. with a fluid-to-plasma concentration ratio of 0.23. The median concentration in the ejaculate (seminal fluid) after 4 hours was 7.4 mg./l. (6.6 mg./l.) and after 12 hours it was 2.0 mg./l. (1.9 mg./l.) with corresponding ejaculate (seminal fluid)-to-plasma concentration ratios of 8.4 (7.7) and 8.0 (6.6), respectively. Thus, ciprofloxacin is concentrated several-fold in ejaculate and seminal fluid but not in prostatic fluid. According to the results the concentrations of ciprofloxacin in prostatic fluid exceed the minimal inhibitory concentration-90% for Enterobacteriaceae but not for Pseudomonas, enterococci and staphylococci, whereas the concentrations in ejaculate and seminal fluid are sufficiently elevated to include the total spectrum of sensitive strains causing bacterial prostatis.