J Korean Androl Soc.  1989 Jun;7(1):37-49.

Diffusion of Antimicrobial Agent into Prostate

• No authors listed

Abstract

The theoretical mechanisms that govern non-ionic diffusion of antimicrobial agents from plasma across the lipid membrance of intact prostatic epithelium into prostatic fluid have been discussed. To permeate the lipid membrane, a drug should be lipid soluble and not bound to plasma prteins. Since only the non-ionized fraction of a drug is soluble, the dissociation cohstant in plasma(pKa value) of the drug is critically important in diffusion. Moreover, the nature of drug as an acid or a base is important because of "ion-trapping" phenomenom, especially at times when the pH value of plasma and prostatic fluid differ significantly just as in an experimental animal(canine) and an earlier findings in human. Lots of investigations have been done the prostatic fluid & tissue/serum ratios of various antimicrobial agents in dogs, only few in human prostatic tissue. In experiment with dogs, among effective antimicrobial agents on Gram negative microorganisms, only level of trimethoprim in prostatic interstitial fluid and prostatic secretion exceeded significantly levels in serum. This finding made the trimethoprim the choice of drug in the treatment of chronic bacterial prostatitis. Therapeutic levels in human prostatic tissue of several antimicrobial agents(minocycline, tobramycin and quinolines) obtained during surgical excision or by biopsy of normal prostate were published. However, the tissue levels should be interpreted as levels of prostatic interstitial fluid. In human, the prostatic fluid & tissue/serum ratio of trimethoprim showed lower than 2:1, unexpectedly. This finding might be related with the higher pH of human prostatic fluid than that of canine prostatic fluid in view of recent reports. Furthemore in the presence of chronic bacterial prostatitis in human, the alkalinity of prostatic secretion increases 10-fold(1 pH unit), which might partly explain the discrepancy between the experimental findings and clinical results of trimethoprim on chronic bacterial prostatitis. The clinical significance of prostatic diffusion data of antimicrobial agents in animal and human without chronic bacterial prostatitis remain uncertain and a re-appraisal of tratment of chronic bacterial prostatitis should be considered.

MeSH Terms

Animals
Anti-Infective Agents
Biopsy
Diffusion*
Dogs
Epithelium
Extracellular Fluid
Humans
Hydrogen-Ion Concentration
Membranes
Plasma
Prostate*
Prostatitis
Tobramycin
Trimethoprim
Anti-Infective Agents
Tobramycin
Trimethoprim