The pharmacokinetic and residue depletion study of eugenol in carp (Cyprinus carpio)

Abstract

Introduction: The pharmacokinetic profile and residue depletion of eugenol in carp (Cyprinus carpio) tissues and plasma were performed by a convenient and reliable high-performance liquid chromatography (HPLC) method.

Methods: The eugenol in carp tissues and plasma was extracted with a mixed solution of acetonitrile and methanol. N-hexane was used to remove lipid impurities. The method was successfully applied to the pharmacokinetic and residue elimination of eugenol in carp after the carp was administered a medicated bath.

Results: The average recoveries of eugenol in tissues and plasma fortified with four concentration levels were 69.0-106.6% and 80.0-86.7%, respectively. The relative standard deviations were < 8.9%. The limit of detection (LOD) was 0.01 μg/g in tissue and 0.008 μg/ml in plasma, respectively. The pharmacokinetic parameter of C_max for eugenol in plasma at the concentrations of 20, 35, and 75 mg/L were 10.86, 17.21, and 37.32 mg/L, respectively. The t_1/2 values were 3.68, 4.22, and 9.31 h. After the investigation of the anesthetic effect, 35 mg/L of eugenol was the optimal concentration for anesthesia. The highest accumulation concentration of eugenol in carp is in the liver and the lowest is in the muscle. In addition, the eugenol in tissue was eliminated rapidly and at a lower level than the LOD at 48 h. According to the residue elimination, the withdrawal time of eugenol was suggested at 5.2 days.

Discussion: These results indicate that the developed method had good linearity and accuracy, and is sensitive enough for the monitoring of eugenol residue in carp. The half-life of eugenol decreased with the increase in drug concentration and the eugenol was eliminated rapidly in carp tissues. 35 mg/L eugenol was recommended as an anesthetic in carp due to its favorable anesthetic effect and no mortality. This study will contribute to the establishment of MRL regulation and setting a withdrawal period.

Keywords: carp; depletion; eugenol; high performance liquid chromatography; pharmacokinetic.

Figure 1

The HPLC chromatograms of blank carp matrices spiked matrices (black line) and the corresponding standard solution (red line): (A-1) blank plasma, (A-2) plasma spiked at 10 μg/ml and the standard solution of 25 μg/ml, (A-3) plasma spiked at LOQ concentration and the standard solution of 0.1 μg/ml; (B-1) blank muscle, (B-2) muscle spiked at 5 μg/g and the standard solution of 20 μg/ml, (B-3) muscle spiked at LOQ concentration and the standard solution of 0.2 μg/ml; (C-1) blank brain, (C-2) brain spiked at 5 μg/g and the standard solution of 20 μg/ml, (C-3) brain spiked at LOQ concentration and the standard solution of 0.2 μg/ml; (D-1) blank liver, (D-2) liver spiked at 5 μg/g and the standard solution of 20 μg/ml, (D-3) liver spiked at LOQ concentration and the standard solution of 0.2 μg/ml; (E-1) blank kidney, (E-2) kidney spiked at 5 μg/g and the standard solution of 20 μg/ml, (E-3) kidney spiked at LOQ concentration and the standard solution of 0.2 μg/ml.

Figure 2

Concentration-time curves of eugenol in carp plasma collected at 0.25, 0.5, 1, 2, 4, 6, 8, 24, and 48 h (n = 10), following medicated bath administration of 20, 35, and 75 mg/L of eugenol.

Figure 3

Concentration-time curves of eugenol in carp muscle, liver, kidney, and brain following a 35 mg/L eugenol of immersion bath (n = 10).