The pharmacokinetics of oxytetracycline in Atlantic cod (Gadus morhua)
Under conditions of intense fish culture it may be necessary to use antibiotics in order to mitigate disease problems. In an effort to reduce the impact of antibiotic residuals on the environment and to eliminate the risk of exposure of these residuals to the consumer optimal treatment regimes must...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
1999
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| Online Access: | https://research.library.mun.ca/795/ https://research.library.mun.ca/795/1/Vatcher_SusanL.pdf https://research.library.mun.ca/795/3/Vatcher_SusanL.pdf |
| Summary: | Under conditions of intense fish culture it may be necessary to use antibiotics in order to mitigate disease problems. In an effort to reduce the impact of antibiotic residuals on the environment and to eliminate the risk of exposure of these residuals to the consumer optimal treatment regimes must be developed. These regimes must account for the use of different antibiotics used on a wide range of species held under varying culture conditions. Culture of the Atlantic cod (Gadus morhua) shows a great deal of potential and at present little information is available on the behaviour of Oxytetracycline (OTC) in this species. -- In an effort to generate baseline pharmacokinetic numbers and to determine the clearance time from organs for OTC in Atlantic cod two experiments were undertaken. Experiment 1 examined the pharmacokinetics of OTC in Atlantic cod following a single dose by oral gavage (Per Os (PO)) or intraperitoneal (IP) injection. Eighteen fish were held at 10°C and administered OTC either intraperitoneally a dose level of 132.8 mg OTC/ kg fish or orally at a dose level of 134.5 mg OTC/ kg fish. Blood samples were taken at 0.5, 3, 6, 12, 36 and 72 hrs and analyzed for OTC levels using High Pressure Liquid Chromatography (HPLC). Noncompartmental modeling identified a time to maximum serum concentration (Tmax) for IP and PO administration of 18 hrs and 6 hrs respectively. The shorter Tmax in the PO group as compared to the IP group is not as expected and may have been the result of precipitation in the injectable solution. Maximum serum concentrations (Cmax) for IP and PO were 140.8 ppm and 1.04 ppm respectively. The higher Cmax in the IP group is as expected and both numbers are in the same order of magnitude as literature values. The relative bioavailability of OTC was calculated to be 0.8%. This low value compares well with literature values for orally administered drugs. T½ for PO administration was calculated to be 184 hours. The PO T½ value was then used to predict a clearance time for OTC of 38.3 days ... |
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