Comparison of Tissue Level of Oxolinic Acid in Fresh and Sea Water Fishes After the Oral Administration

Abstract

The tissue levels of oxolinic acid, an antibacterial agent, in fresh water fishes (rainbow trout and tilapia) and sea. water fishes (red sea bream, Japanese mackerel, yellowtail, and Japanese flounder) at 3, 6, 12, 24, 48, and 72h after oral administration (40mg/kg) were determined by high performance liquid chromatography. High concentrations of oxolinic acid were observed in the order of kidney <liver<muscle<serum in all the specises examined. In rainbow trout, each tissue level reached maximum (kidney; 15.0, liver; 5.9, muscle; 4.8, serum; 2, 2μg/g) at 72h post dosing. In tilapia, the highest concentrations of liver (13.0μg/g), muscle (4.9μg/g), and serum (9.1μg/g) were observed at 12h, while that of kidney (11.0μg/g) was found at 48h. In the other 4 species of sea water fish, the drug concentration in each tissue went up to the level of O.3-6.3μg/g within 12h and went down below the loewst detectable limit at 72h. The time required for the tissue level to reach a maximum concentration was shorter in the sea water fish than in the fresh water fish. The tissue level in the sea water fishes was lower than in the fresh water fishes. Thus, oxolinic acid appears to remain much more in the fresh water fishes than in the sea water ones for a long time.
The drug concentrations in coho salmon cultured in fresh water and sea water were compared. The tissue level in the coho salmon cultured in fresh water show a the similar tendency to that rainbow trout, while the drug concentration in the coho salmon cultured in sea water changed similarly to that of the sea water fish.