title: Liposome disposition in vivo IV: the interaction of sequential doses of liposomes having different diameters.
abstract: In order to evaluate the degree to which liposomes of the same composition but of different size interact with organ binding sites, a series of pre-dose studies have been carried out in mice. Two sizes of multilamellar liposomes were used: large (L) liposomes averaging 0.5 micrometer in diameter and small (S) liposomes averaging 0.06 micrometer in diameter. Lipid composition was phosphatidylcholine/phosphatidic acid/cholesterol/alpha-tocopherol in the molar ratio 4:1:5:0.1. Experiments consisted of a saturating pre-dose of either non-radioactive L- or S-liposomes followed at various times by a test dose of radioactively labelled L- or S-liposomes. When pre-dose and test dose were of the same diameter, an interaction was observed. A pre-dose of L-liposomes also interacted with a test dose of S-liposomes but a pre-dose of S-liposomes did not interact with a test dose of L-liposomes. All disposition effects were reversible, returning to control values within 24 h. These results indicate that L- and S-liposomes of identical composition may associate with different hepatic binding sites and that a class of non-specific binding sites available to S-liposomes but not to L-liposomes may exist.
mesh_terms: D000818:Animals; D008081:Liposomes / Q000378:metabolism*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010316:Particle Size; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D008081:Liposomes