TEMPERATURE-RELATED ABSORPTION AND EXCRETION OF OXYTETRACYCLINE IN RAINBOW-TROUT (SALMO-GAIRDNERI R)

The absorption and elimination of oxytetracycline in serum, muscles and liver of rainbow trout were studied at 5°, 10° and 16°C after a single oral dose of 75 mg/kg fish. The absorption of the drug was relatively rapid, with maximum concentrations reached in serum within 1 h at 16°C, 12 h at 10°C and 24 h at 5°C. The highest drug levels were measured in bile and liver followed by serum and muscle tissue. The elimination of the drug was markedly temperature-dependent. The half-life of oxytetracycline in rainbow trout serum was 4.8 days at 16°C, 6.1 days at 10°C and 8.9 days at 5°C. The predicted withdrawal times varied from 27 days to 135 days depending on temperature and tissue studied. Results obtained from laboratory experiments are compared with results from field trials. © 1990.