Pharmacokinetics and bioavailabilities of 14C-keto-carotenoids, astaxanthin and canthaxanthin, in rainbow trout, Oncorhynchus mykiss

The pharmacokinetics and bioavailabilities of C-14-astaxanthin and C-14-canthaxanthin were studied in the blood of rainbow trout following intra-arterial (i.a.) and oral (p.o.) administration. Sixteen months old 1 kg trout were cannulated in the dorsal aorta. [6,7,6',7'-C-14]-keto-carotenoids were administered i.a. and p.o. at a dose of 573.5 kBq kg(-1) fish body weight for astaxanthin and 836.2 kBq kg(-1) fish body weight for canthaxanthin. After i.a. distribution, total body clearance (Cl-tot) was 17.30 +/- 20.29 mL kg(-1) of fish h(-1) for C-14-canthaxanthin and 3.30 +/- 1.50 mL kg(-1) of fish h(-1) for C-14-astaxanthin. The volume of distribution at steady-state (V-ss) was 208.32 +/- 124.79 mL kg(-1) of fish and 71.84 +/- 64.15 mL kg(-1) of fish for C-14-canthaxanthin and C-14-astaxanthin respectively. Less than 0.4% of the administered radioactivity was recovered in urine. Radioactivity (expressed as percent of the dose) excreted in the bile of fish that received C-14-canthaxanthin by i.a. route was 20-fold higher than that observed for fish treated p.o. This ratio was lower for C-14-astaxanthin (7.6-fold). The mean keto-carotenoid bioavailabilities calculated were 10-15% for both compounds. Findings suggest one daily astaxanthin application is preferable, while 12-h time intervals between applications are preferable for canthaxanthin.