Astaxanthin and Canthaxanthin Kinetics after Ingestion of Individual Doses by Immature Rainbow Trout Oncorhynchus mykiss

Kinetics of a 100 μg oral dose of astaxanthin (AX) or canthaxanthin (CX) was determined from serum AX or CX concentration−time curves in 234 immature rainbow trout, Oncorhynchus mykiss, with a mean body weight of 300 g. Carotenoid concentrations in serial serum were measured using HPLC. The net change in mean peak serum concentrations in rainbow trout fed AX or CX reached 4.4 ± 1.0 nmol/mL of serum at 18 h post-dosing for AX and 2.9 ± 0.5 nmol/mL of serum at 12 h post-dosing for CX. The maximum level of CX serum was 1.6 lower than that of AX. In terms of absorption speed, AX and CX are likely equivalent. The relative bioavailability of CX, with respect to AX taken as the reference, corresponds to 33.5%. AX was more slowly removed from the serum than CX. The mean retention time of AX (56.4 h) was 2.4-fold that of CX (23.1 h). Keywords: Astaxanthin; canthaxanthin; serum kinetics; pharmacokinetics; rainbow trout