Pharmacokinetics of Eugenol in Japanese Flounder, Paralichthys olivaceus

Eugenol, which has been used as an anesthetic for fish, was administered to Japanese flounder, Paralichthys olivaceus (127 +/- 50.8g), by bath treatment at concentrations of 0.025, 0.125, and 0.25 mL/L seawater for 10min and intramuscular injection at 40L/fish to investigate the pharmacokinetic characteristics of eugenol in the plasma of Japanese flounder. In the bath treatment test, plasma eugenol concentration increased with increasing eugenol concentration up to 0.125 mL/L and reached steady state within 5min. After a 10-min bath treatment in 0.25 mL/L eugenol, plasma eugenol concentration was about 58.4 mu g/mL. After transfer into running seawater, plasma eugenol concentration decreased biphasically with half-lives of 0.0296h (-phase) and 0.289h (-phase). The AUC(00000800) was about 16.5 mu gh/mL. In administration by intramuscular injection, plasma eugenol concentration increased rapidly after administration and decreased biphasically with half-lives of 0.0329h (-phase) and 8.08h (-phase). The AUC(00000800) was about 52.5 mu gh/mL. In both methods of administration, Japanese flounder with average weight of 127g were effectively anesthetized when plasma eugenol concentrations were between 2.19 and 4.88 mu g/mL.