Interaction between erythrocytes and free phospholipids as an emulsifying agent in fat emulsions or drug carrier emulsions for intravenous injections

Hemolysis caused by the interaction between rabbit erythrocytes and oil-in-water emulsions (e.g., fat emulsions or drug carrier emulsions for intravenous injections) prepared with various oil concentrations was investigated. In emulsions prepared with oil concentrations in the range of 2.5-12.5%, the percentage of both hemolysis and free purified egg yolk lecithins (PEL) in the water phase of the emulsions decreased with the increased oil concentration and became constant above 12.5% oil concentration. The change in free PEL percentage in the water phase of the emulsions prepared with various oil concentrations showed the same relationship as that of the percentage hemolysis caused by the interaction between rabbit erythrocytes and emulsions prepared with various oil concentrations. No hemolysis caused by an interaction between rabbit erythrocytes and vesicles prepared with PEL at a concentration of 0.012% was observed. However, hemolysis levels of 64.2% and 91.1% were observed at PEL concentrations of 0.12% and 1.2%, respectively. These results led to the conclusion that hemolysis caused by the interaction between erythrocytes and emulsions was due to PEL vesicles in the water phase of the emulsions.