[Pharmacokinetics of tobramycetin and gentamycin and the mechanism of their elimination by the kidneys].

After subcutaneous administration of tobramycetin (tobramycin) to rabbits in single doses equivalent to the daily therapeutic doses for humans calculated for the body surface and those exceeding them by 3 times, the antibiotic was rapidly absorbed into the blood and detected within 30 and 72 hours respectively. Tobramycetin penetrated into all organs of the animals. Its highest levels were found in the kidneys and the lowest in the brain tissue. Tobramycetin was excreted with the urine in amounts equal to 80 per cent of the dose administered. No cumulation of the antibiotic was observed in the dog blood after its repeated subcutaneous administration. Comparative investigation of tobramycetin and gentamicin pharmacokinetics in rabbits after intravenous administration showed no significant differences. Both antibiotics were mainly excreted with the urine: the renal clearance averaged to 65 per cent of the total clearance, the time of a two-fold decrease in the blood levels of the antibiotics was on an average 40 minutes. Tobramycetin and gentamicin were excreted with the kidneys by means of glomerular filtration with insufficient reabsorption in the tubules.