Lipid emulsions as a novel system to reduce the hemolytic activity of lytic agents: mechanism of the protective effect

The hemolytic activity of sodium oleate, a high lyric agent, was investigat ed in different surfactant solutions and lipid emulsion formulations. A new explanation of the protective function of these systems is proposed. It wa s found that the hemolytic activity of the lytic agent was greatly decrease d in solutions and/or dispersions with the surfactant Cremophor EL, Solutol H16 and phospholipids, which can usually build a micellar or liposomal str ucture. In the case of F68, where the micelle formation is still controvers ial, the hemolytic activity of the lytic agent was practically not affected and complete hemolysis was observed. In contrast to this, all emulsion for mulations, independent of the emulsifier type, showed a stable erythrocyte behavior. Additionally, in the case of lipid emulsions only, a larger amoun t of the lyric agent could be added without any remarkable increase in the hemolytic activity. As an explanation for these effects it is proposed that the lytic agent is either incorporated into the lipophilic core or interca lates between the emulsifier molecules at the interface. This decreases the direct contact of the lytic agent with the erythrocyte membrane. As a resu lt, the erythrocytes will effectively be protected from hemolytic damage, w hich can otherwise be induced by such substances. (C) 2000 Elsevier Science B.V. All rights reserved.