MODIFICATION OF LIPOSOMES BY ADDITION OF HCO60 .1. TARGETING OF LIPOSOMES TO LIVER BY ADDITION OF HCO60 TO LIPOSOMES

The influence of HCO60 on the blood clearance and tissue distribution of soybean phosphatidylcholine (PC) liposomes, encapsulating alpha-tocopherol as a marker, was studied in rats. The liposomes were prepared by the hydration method from a lipid film containing different amounts of HCO60, and by extrusion through a 0.1 mum polycarbonate membrane filter. The blood clearance and liver uptake of alpha-tocopherol after i.v. administration increased with increasing the amount of HCO60 the liposome contained. With 80 wt% HCO60 liposomes, the accumulation of alpha-tocopherol in the liver was approximately three-fold that of the 100% PC liposomes. The uptake by lungs, spleen and kidneys did not change with the addition of HCO60. The findings obtained in a gel-filtration study suggested that alpha-tocopherol is not removed from the liposomes, with or without HCO60, by rat plasma proteins and the HCO60 micelle may form a complex with rat plasma proteins. Our findings suggest that liposomes containing large amounts of HCO60 (more than 60 wt%) will be useful for delivering drug to the liver.