In vitro stability of liposomes in the presence of polymers, trehalose and sodium taurocholate

We report the influence of synthetic polymers, trehalose and sodium taurocholate on the stability of both MLVs* and SPLVs prepared from a range of lipids including synthetic polyhydroxyl lipids. In the absence of cryoprotective agents liposomes were found to release greater than 90 per cent of encapsulated marker when exposed to freeze-thawing or freeze-drying procedures. In the presence of polyvinylpalmitate a marginal enhancement of stability towards freeze-drying was observed, the effect being most marked with cholesterol-containing liposomes. Trehalose was also found to stabilize all preparations investigated towards freeze-drying. In particular SPLVS prepared from (C18:0, C14:0-GMG):EPC:C retained in greater than 90 per cent of the entrapped marker. Addition of polymers to trehalose-containing SPLVS did not further increase the stability. SPLVS prepared from lipids possessing a high transition temperature demonstrated enhanced stability in the presence of bile salts. This effect was most marked with SPLVs prepared from (C18:0, C22:0-GMG):C.