Pharmacokinetics and first-pass metabolism of astaxanthin in rats

Abstract

Astaxanthin is a carotenoid with antioxidant, anti-cancer and anti-inflammatory properties. The pharmacokinetics of astaxanthin after its intravenous (5, 10, and 20mg/kg) and oral (100 and 200mg/kg) administration and its first-pass extraction ratios after its intravenous, intraportal or intragastric (20mg/kg) administration were evaluated in rats. The pharmacokinetic parameters of astaxanthin were dose dependent after its intravenous administration, due to the saturable hepatic metabolism of astaxanthin, but dose independent after oral administration. The gastrointestinal absorption of astaxanthin followed the flip-flop model. The hepatic and gastrointestinal first-pass extraction ratios of astaxanthin were approximately 0490 and 0901, respectively. Astaxanthin was metabolised primarily by hepatic cytochrome P-450 1A1/2 in rats. Astaxanthin was unstable up to 4h incubation in four rat gastric juices and up to 24h incubation in various buffer solutions having a pH of 1-13. The tissue/plasma ratios of astaxanthin at 8 and 24h after its oral administration (100mg/kg) were greater than unity for all tissues studied, except in the heart, at 8h, indicating that the rat tissues studied had high affinity for astaxanthin. © 2010 The Authors.