[Concentration of antimicrobial agents in male genital organs]

The relationship between the concentrations of various antimicrobial agents in the genital organs of male rats, serum, liver and kidney after oral administration, intramuscular infusion and i.v. infusion were systematically compared and studied. The concentration of Ampicillin in human prostatic tissues after intramuscular infusion was also measured. The drug concentration in the prostatic tissues after oral administration of nalidixic acid (20 mg/kg) was highest 21.5 micrograms/g (2-hour value) which was about 4 times the serum level, followed by chloramphenicol, Cefalexin, Ampicillin, piromidic acid and erythromycin. The concentration of Ampicillin and Cefaloridine in the prostatic tissues after intramuscular infusion was high, but the concentration of Cefazolin, was low after both intramuscular infusion and i.v. infusion. The drug concentration in the prostatic tissues after i.v. infusion of Cefaloridine, Erythromycin, and Ampicillin was high. The concentration of Erythromycin was high only after i.v. infusion. The concentration of both Chloramphenicol and Gentamicin in the blood, and in the prostatic tissues were low. Of the drugs tested, the concentration of Ampicillin in human prostatic tissues was the highest being about 8 micrograms/g at 60 minutes after intramuscular infusion, which was about 40% of its concentration in the blood. The concentrations of antimicrobial agents in the epididymis and testis of the rats were low. Even the relatively high values were only about 10% of the concentration in the blood. The concentration of nalidixic acid in the prostatic tissues was 4 times as high as that of Piromidic acid. In summary, the antimicrobial agents showing high concentrations in the prostatic tissues were nalidixic acid by oral administration, Ampicillin and Cefaloridine by intramuscular infusion, and i.v. infusion, which showed relatively high concentrations in the blood. Irrespective of the route of administration, the concentrations of Chloramphenicol and Gentamicin in the male genitals were low. The drug concentration in the testis was very low irrespective of the chemotherapeutic and administration form. This seems to signify the presence of the so-called blood-testis barrier to protect the important function of spermatogenesis.