Diffusion of ciprofloxacin into prostatic fluid.

To determine whether ciprofloxacin might be efficacious in therapy for chronic bacterial prostatitis, its diffusion into prostatic fluid was studied in ten healthy volunteers. One hour after administering 500 mg ciprofloxacin, the concentration of ciprofloxacin was measured by the agar diffusion method and bioassay. Serum levels were twice as high as in seminal fluid; however, 12 and 24 hours later concentration in seminal fluid was tenfold higher than in serum. Split ejaculates were examined to determine the secretory pattern of ciprofloxacin into seminal fluid. The two fractions also showed tenfold concentration. Ciprofloxacin concentration in expressed prostatic secretion ranged from 15 to 0.9 mg/l, thus indicating pronounced diffusion of ciprofloxacin into the prostatic fluid.