Antimicrobial substances in secretion, interstitial fluid, and tissue of normal and infected canine prostate glands.

Seven antimicrobial substances--three basic, three acidic and one amphoteric--were given in constant infusion experiments to dogs to monitor their distribution in the prostate gland. In some of the dogs an experimental bacterial prostatitis had been induced prior to the experiments. Drug levels were measured in plasma (P1), prostatic interstitial fluid (PIF), prostatic secretion (PS) and prostatic tissue (PT). Drug levels in PIF differed considerably from those in PS. In PS and PIF only basic substances exceeded the corresponding plasma levels. Concentrations of acidic substances in PS and PIF never exceeded the simultaneous plasma levels. In PIF the concentration of these drugs was significantly higher than in PS. Our results show that previous studies of prostatic secretion levels only were too optimistic for alkaline drugs and too pessimistic for acidic drugs.