Abstract
In order to examine the possibility of utilizing liposomes as drug carriers, the fate of 14C-inulin and 131I-insulin entrapped in negatively or positively charged liposomes after intravenous injection was investigated in rats. The clearance rate from plasma of 14C-inulin entrapped in liposomes was faster than that of free 14C-inulin, and decreased with the increase of the liposomal concentration. Further, liposome-entrapped drugs were recovered mainly in the liver, especially in Kupffer cells, as well as the spleen, and such hepatic accumulation was reduced by pretreatment with methyl palmitate to a great extent. From these results, it appears that the large proportion of drugs entrapped in liposomes is delivered into the RES intact and their distribution pattern depended on the liposomal surface properties, but not on the kind of drugs entrapped.
