Pharmacokinetics of eugenol in rainbow trout (Oncorhynchus mykiss)

Clove oil, eugenol being its main constituent, has been used to anaesthetise fish for the last decade however no pharmacokinetic study of this drug has yet been realised in fish. The objective of the present study was to determine the pharmacokinetic parameters following immersion of rainbow trout (Oncorhynchus mykiss) in a eugenol solution. A total of 30 fish (n = 3 per time point) of similar length and weight were immersed in a solution of 75 mg/L of eugenol for 15 min. After thorough rinsing, individuals were placed in a recuperation tank in oxygenated conditioned water. Blood samples were collected at selected time points (at predose and at 0.25, 0.5, 1, 2, 4, 6, 8, 24 and 48 h) post-exposition. The samples were then submitted to mass spectrometry analysis using dansyl-chloride derivatisation. Pharmacokinetic results obtained are a Cmax of 10.53 μg/mL, a AUC0−t 16.55 μg h/mL, AUC0 − inf 17.04 μg h/mL and a half life of 12.14 h. These results indicate that eugenol is well absorbed and eliminated using a bath immersion at 4 °C. The long half life suggests that eugenol may accumulate in trout following repeated administration and further studies are required to evaluate its potential toxicity.