Prolonged circulation time of doxorubicin-loaded liposomes coated with a modified polyvinyl alcohol after intravenous injection in rats

Passive Targeting of Doxorubicin with Polymer Coated Liposomes in Tumor Bearing Rats.

“…Both drug encapsulation and polymer coating were carried out at the same time according to a modified pH gradient (interior acidic) method previously reported. 16) In short, noncoated liposomes were prepared by adding 4 ml of 50 mM sodium carbonate in saline to the mixture of small-unilamellar liposomes (1 ml) and aqueous doxorubicin solution (1 ml). The resultant mixture was shaken for 10 min at 60°C, followed by incubation for 1 h at 10°C (non-coated liposomes).…”

“…The encapsulation efficiency of drug was almost 92% regardless of polymer coating as determined by the previously described method. 16) In measuring the change in zeta potential of the liposomes by HPMC and HPMC-R coating, negatively charged liposomes 100 nm in diameter were prepared with DMPC, DCP and cholesterol of 7 : 3 : 1 in a molar ratio by the hydration method, followed by sonication (UR-200P, Tomy Seiko Co.). Polymer-coated liposomes were prepared by mixing the resultant liposomal suspension (1 ml) with an equal amount (1 ml) of polymer solution (0-1%), followed by incubation at 10°C for 1 h.…”

“…The drug extracted into toluene/butanol (1 : 1, v/v) was subjected to HPLC assay with a fluorescence detector (Jasco FP-920, excitation 480 nm, emission 590 nm) in a manner previously reported. 16) The targeting efficiency of the liposomal formulations to the tumor site was calculated by the following equations reported by Takakura and Hashida.…”

“…It was also confirmed that the PVA-R coated liposomes, as well as PEGulated stealth liposomes, prolonged the circulation by decreasing their RES uptake in rats. 16,17) In comparing this polymer coating method with that for the PEGulated liposomes, the former is characteristic in coating the liposomes after preparation of a drug containing liposomal particles. 16) In this paper, the passive targeting properties of the polymer coated liposomes were evaluated with the tumor accumulation of the antitumor drug, doxorubicin, entrapped in the liposomes by intravenously injecting the liposomal drug into tumor bearing rats.…”

“…16,17) In comparing this polymer coating method with that for the PEGulated liposomes, the former is characteristic in coating the liposomes after preparation of a drug containing liposomal particles. 16) In this paper, the passive targeting properties of the polymer coated liposomes were evaluated with the tumor accumulation of the antitumor drug, doxorubicin, entrapped in the liposomes by intravenously injecting the liposomal drug into tumor bearing rats. For coating the liposomal surface, two different hydrophilic polymers bearing hydrophobic anchors in the molecules, PVA-R and a modified hydroxypropylmethylcellulose (HPMC-R), were used.…”