DISTRIBUTION OF OXYTETRACYCLINE IN GENITAL-TRACT TISSUES OF POSTPARTUM COWS GIVEN THE DRUG BY INTRAVENOUS AND INTRAUTERINE ROUTES

  • 1 January 1983
    • journal article
    • research article
    • Vol. 44  (5) , 764-769
Abstract
Oxytetracycline (OTC) was administered by constant i.v. infusion to 3 healthy postpartum cows at rates predicted to approach a steady-state plasma concentration of 5 .mu.g/ml. After 8 h of constant i.v. infusion, genital tissues were surgically removed. The mean plasma-to-tissue ratios of concentrations of OTC were 0.95, 1.33, 1.88 and 1.04 (2 cows only) for caruncles, endometrium, uterine wall and ovaries, respectively. Differences between the ratios of any 2 of the uterine tissues were statistically significant (P < 0.05). Intrauterine (i.u.) infusions of 5.5 mg of OTC/kg were administered to 3 healthy postpartum cows and 3 postpartum cows with metritis. The mean values of the fraction of the drug absorbed from the uteri of cows given i.u. infusions of OTC were 0.50 and 0.23 for healthy postpartum cows and postpartum cows with metritis, respectively. Concentrations of OTC were high in the caruncles and endometrium of all cows at 24 h after i.u. infusions of the drug. Concentrations in the plasma, uterine wall and ovaries were low, with mean concentrations of OTC in these tissues in postpartum cows with metritis being lower than those in the same tissues of healthy postpartum cows. Computer-simulated genital tissue concentrations of OTC after twice daily i.v. doses of 11 mg/kg indicated that this dosage regimen would provide postpartum uterine tissue concentrations > 5 .mu.g/g throughout the dosage interval in all tissues, except the uterine wall.