Uptake of bixin by blood lipoproteins and leukocytes in cats

Bixin was used originally as remedies for asthma, pleurisy, sunstroke and burns. The uptake of bixin in companion animals is unknown. We fed domestic shorthair cats bixin extracted from the annatto seed (1.6% bixin, <0.3% norbixin). In experiment 1, domestic cats (3 yr old; n = 8/dose) were orally dosed with 0, 1, 5 or 10 mg bixin and blood was taken at 0, 1, 2, 4 and 8 h after feeding. Plasma bixin concentrations in cats fed 0, 1, 5 or 10 mg bixin increased dose-dependently and reached maximum concentrations of 0, 9, 45 and 119 nmol/L, respectively. Peak bixin concentration was observed at 1 h after dosing, with an elimination half-life of 2 h. The uptake profile for norbixin was similar to bixin except that norbixin concentration averaged 10–30 times lower than bixin. In experiment 2, cats were orally administered 0, 1, 5 or 10 mg bixin daily for 14 d. Blood was taken 1 h after dosing on d 0, 1, 3, 6, 9, and 14 to measure bixin uptake in plasma, lipoproteins (d 6 and 14) and leukocyte subcellular fracti...