Liposomes sterically immobilized in agarose gel beads as stationary phase for column chromatography of drugs

Liposomes entrapped in Sepharose 2B gel were used to study interactions between drugs and lipid compounds. Liposomes (soybean lecithin or soybean lecithin plus 2 or 5% sodium cetylphosphate) were sterically immobilized in agarose gel by the dialysis method. These were employed as stationary phases for column chromatography of twentythree bioactive molecules of different physicochemical properties and therapeutic activity. The stationary phases could be prepared reproducibly and were stable for several Chromatographie runs. The retention behaviour of drugs on these columns was defined in terms of distribution coefficient K n. The drugs were differently retarded as a result of the different kinds of interactions established with the lipid vesicle components : the results indicated that, on columns with lecithin liposomes, drug retention was primarily due to Hydrophobie interactions, while with sodium cetylphosphate/lecithin vesicles, the presence of charged surfaces allowed the drugs to bind ionically to the bilayer components.