Absorption and Excretion of Cefquinome in Coho Salmon (Oncorhynchus kisutch) in Freshwater at 10 °C

The absorption and elimination of cefquinome in serum and tissues of coho salmon were studied. The study was performed in freshwater at 10 degrees C with fish weighing 100 +/- 5 g (mean and standard deviation). Single doses of 5, 10 and 20 mg/kg were administered intraperitoneally to 30 fish for each dose. The maximum concentration occurred in the following order; kidney and liver > serum > muscle > brain. The pharmacokinetic analysis and predictive withdrawal times were calculated using only the dose of 20 mg/kg body weight. The peak cefquinome concentrations (Cmax) in serum (3.35 +/- 0.45 micrograms/ml) and muscle (2.87 +/- 0.53 micrograms/g) were achieved at 12 h. In the brain, the Cmax was 2.18 micrograms/g at 6 h. The half-lives (t1/2) in serum, muscle, brain, liver and kidney were 20.56, 8.93, 9.35, 113.61 and 119.48 h, respectively. With the detection limit of 0.015 microgram/g for the cefquinome, the predicted withdrawal time with 95% confidence for muscle tissue was 104.2 h at 10 degrees C for the 20 mg/kg dose. The results suggest that cefquinome could be efficacious and safe for the consumer in treating bacterial diseases of coho salmon in fresh water. Nevertheless, future studies are required in order to determine an adequate dose with the corresponding withdrawal times.