Pharmacokinetics and bioavailability of oxytetracycline in Atlantic salmon held in seawater at different temperatures

A pilot study was undertaken to evaluate the suitability of sampling times, form of oral dose, and trends in the plasma pharmacokinetics of oxytetracycline (OTC). The pilot study consisted of groups of ten Atlantic salmon held in reconstituted seawater at 10$\sp\circ$C treated with OTC at two concentrations, 100 mg and 200 mg OTC/kg body weight, either as a single intraperitoneal injection, or as a single oral dose via a gelatin capsule or in a 0.2% w/v aqueous Bacto-Agar slurry administered by stomach intubation. Gelatin capsules were slow to hydrolyze. Consequently, of the two methods of administration of OTC via the oral route, the aqueous Bacto-agar slurry was the preferred method. Since the elimination phase had not commenced by the end of the sampling time of 36 h, it was not possible to draw any conclusions about the pharmacokinetics of OTC elimination.

The low apparent bioavailability of oxytetracycline in Atlantic salmon held in seawater at 10$\sp\circ$C and 15$\sp\circ$C described in this study supports earlier accounts of low bioavailability of oxytetracycline in teleosts. (Abstract shortened by UMI.).