Plasma lipoproteins as drug carriers: Pharmacological activity and disposition of the complex of β-sitosteryl-β-D-glucopyranoside with plasma lipoproteins

The ability of plasma lipoproteins to act as carriers in sitespecific drug delivery systems was evaluated by determining the disposition and pharmacological effects of β-sitosteryl-β-d-glucopyranoside (SG, 3). In the disposition studies, [3H]SG was absorbed from the intestinal tract by the formation of chylomicrons and was specifically associated with lipoproteins in vivo. [3H]SG was incorporated into various rat plasma lipoproteins in vitro. [3H]SG complexed with the lower density lipoproteins (d < 1.063 g/mL), especially with the intermediate density lipoproteins (1.006 ≤ d < 1.019 g/mL) which disappeared more rapidly from the circulatory system than the [3H]SG complexed with the higher density lipoproteins (d ≥ 1.063 g/mL) following intravenous administration to rats. In pharmacological studies, the hemostatic effect of SG in mice and the inhibitory effect of SG on vascular permeability in rats were only observed after intravenous administration of the complexes of SG with the lower density lipoproteins. The same results were obtained after the intravenous administration of the complexes of SG with human and mouse lipoproteins.