title: Specific targeting of the antiviral drug 5-iodo 2'-deoxyuridine to the parenchymal liver cell using lactosylated poly-L-lysine.
abstract: In this study, we describe the development and characterization of lactosylated poly-L-lysine as a potential carrier for targeting anti-viral drugs to the parenchymal liver cell. Poly-L-lysine (M(r) 38,000) was modified with 2 to 130 lactose residues per molecule poly-L-lysine. In vitro competition studies for the asialoglycoprotein receptor on parenchymal liver cells using 125I-asialoorosomucoid as radioligand revealed that mild modification of poly-L-lysine with only five lactose residues was sufficient for high affinity competition. In vivo studies showed that, after injection of poly-L-lysine modified with at least five lactose residues, about 70-80% of the injected dose was taken up by the liver. Preinjection of N-acetyl galactosamine almost completely blocked the hepatic uptake of lactosylated poly-L-lysine, indicating that galactose-recognizing receptors are involved. At 10 min following injection, the contribution of the various liver cell types to the hepatic uptake of lactosylated poly-L-lysine was determined; the parenchymal cell appeared to be responsible for more than 98% of the total liver uptake. To assess the applicability of lactosylated poly-L-lysine as an anti-viral drug carrier, it was derivatized with 4 to 15 residues of the antiviral drug 5-iodo 2'-deoxyuridine, 5'-monophosphate per molecule poly-L-lysine (4-16% by weight) via an acid-labile phosphamide bond. Maximally 0.7% of the conjugated 5-iodo 2'-deoxyuridine 5'-monophosphate was released after 1 h incubation of the drug/carrier conjugate with serum at 37 degrees C, thus establishing the stability of the conjugate in serum. The drug-carrier conjugate was rapidly cleared from the bloodstream within 1 min. Approximately 90% of the injected dose could be recovered in the liver. The parenchymal liver cell was responsible for 97% of the hepatic uptake. In vitro studies on the kinetics of endocytosis of lactosylated poly-L-lysine, derivatized with 5-iodo 2'-deoxyuridine 5'-monophosphate, by parenchymal liver cells revealed that the ligand was immediately internalized and, after a 10-min lag phase, deacetylated. Internalization and degradation did not occur in the presence of 100 mM N-acetyl galactosamine. In conclusion, the bioavailability of 5-iodo 2'-deoxyuridine 5'-monophosphate to the parenchymal liver cell is dramatically enhanced as a result of the conjugation of the anti-viral drugs to lactosylated poly-L-lysine. Accordingly, lactosylated poly-L-lysine constitutes a suitable carrier for targeting anti-viral drugs to the parenchymal liver cell.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Leiden/Amsterdam Center for Drug Research, University of Leiden, The Netherlands.
authors.forename: E A
authors.initials: EA
authors.lastname: Biessen
authors.forename: D M
authors.initials: DM
authors.lastname: Beuting
authors.forename: H
authors.initials: H
authors.lastname: Vietsch
authors.forename: M K
authors.initials: MK
authors.lastname: Bijsterbosch
authors.forename: T J
authors.initials: TJ
authors.lastname: Van Berkel
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000008:administration & dosage; D037263:Asialoglycoprotein Receptor; D001212:Asialoglycoproteins / Q000378:metabolism; D001667:Binding, Competitive; D003856:Deoxyuracil Nucleotides / Q000378:metabolism; D004337:Drug Carriers; D006801:Humans; D007065:Idoxuridine / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008099:Liver / Q000166:cytology* / Q000378:metabolism; D008297:Male; D011107:Polylysine / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000378:metabolism
chemical_list: D000998:Antiviral Agents; D037263:Asialoglycoprotein Receptor; D001212:Asialoglycoproteins; D003856:Deoxyuracil Nucleotides; D004337:Drug Carriers; D011956:Receptors, Cell Surface; C056075:iododeoxyuridylate; D011107:Polylysine; D007065:Idoxuridine