title: In vivo studies on the role of complement in the clearance of liposomes in rats and guinea pigs.
abstract: The ability of complement (C) system to remove liposomes from blood circulation was examined in vivo using rat and guinea pig as models. Although the liposomes were not degraded in guinea pig serum in vitro, they were degraded remarkably in guinea pig circulation, as assessed by the urinary excretion of [3H]inulin released from liposomes. The suppression of rat C system to 64% normal C hemolytic activity by treating animals with K76COOH agent resulted in a significant decrease in both the uptake of liposomes by liver and the release of [3H]inulin, providing in vivo evidence for C-mediated clearance of liposomes in rats via uptake by macrophages and degradation in blood circulation, respectively. On the other hand, the K76COOH-induced suppression of C (70% normal hemolytic activity) in guinea pigs slightly increased both the hepatic uptake and the release of [3H]inulin. In addition, the hepatic uptake and in vivo degradation in guinea pigs varied in an opposite manner when the animals were preloaded by empty liposomes or when the liposome size and cholesterol content varied. These results suggest there is a difference between the factors involved in liposome degradation and the factors involved in hepatic uptake and also support the likelihood that there is no C-mediated degradation in guinea pigs.
authors.affiliation: Faculty of Pharmaceutical Sciences, The University of Tokushima, Japan.
authors.forename: T M
authors.initials: TM
authors.lastname: Huong
authors.forename: H
authors.initials: H
authors.lastname: Harashima
authors.forename: H
authors.initials: H
authors.lastname: Kiwada
mesh_terms: D000818:Animals; D003167:Complement Activation / Q000187:drug effects; D003165:Complement System Proteins / Q000378:metabolism / Q000502:physiology*; D004337:Drug Carriers; D016503:Drug Delivery Systems; D006168:Guinea Pigs; D006877:Hydroxamic Acids / Q000008:administration & dosage / Q000494:pharmacology; D008081:Liposomes / Q000378:metabolism / Q000493:pharmacokinetics*; D008297:Male; D008657:Metabolic Clearance Rate; D051381:Rats; D017208:Rats, Wistar; D013045:Species Specificity; D014018:Tissue Distribution
chemical_list: D004337:Drug Carriers; D006877:Hydroxamic Acids; D008081:Liposomes; C003486:2-methyl-3-(4-phenylpiperidino)propionohydroxamic acid hydrochloride; D003165:Complement System Proteins