ETHYL M-AMINOBENZOATE METHANESULFONATE DEPENDENT AND CARRIER DEPENDENT PHARMACOKINETICS OF EXTREMELY LIPOPHILIC COMPOUNDS IN RAINBOW-TROUT

Significant differences were found in both uptake and pharmacokinetics in fish when six lipophilic compounds were dosed by gavage in either an oil or an gelatin carrier. Pharmacokinetics were also different whe n fish were anaesthetized with ethyl m-aminobenzoate methanesulfonate (MS-222) before dosing. The highest uptake percentages, uptake rates a nd concentrations of the compounds were found in the fish which were g iven the gelatin carrier only. MS-222 decreased the uptake of the comp ounds. Absorption of the compounds from oil was lower than from gelati n. In addition, absorption from oil continued for 21 d, which lasted l onger than from gelatin. In the fish which were given the gelatin, the concentrations of the compounds in both muscle and liver showed a com pound dependent decrease in the course of the experiment. In general, in all treatments higher concentrations were found in liver than in mu scle. For each treatment, the absorption rates of pentachlorobenzene, hexachlorobenzene, 2,2',5,5'-tetrachlorobiphenyl and 2,2',4,4',5,5'-he xachlorobiphenyl were similar, but different from the other treatments . It can be concluded that the experimental methodology significantly affects the pharmacokinetic parameters that are used to model the bioc oncentration of hydrophobic chemicals in the environment.