Interaction between erythrocytes from various animals and emulsions stabilized with various lecithins.

The degree of hemolysis caused by the interaction between erythrocytes from various animals and emulsions stabilized with various lecithins was evaluated as a measure of the safety of emulsions for drug carriers. The stability of the emulsions was estimated using the gradient of the slope derived from the direct linear correlation between the percentage hemolysis and the phosphatidylcholine (PC) content of the erythrocyte membrane. When members of the egg lecithin (EPC) series were used as emulsifiers of emulsions, the percentage hemolysis increased as the PC content of the erythrocyte membrane increased and as the sphingomyelin (SM) content of the erythrocyte membrane decreased. Lysolecithin, a contaminant present in the emulsifying agent of emulsions, did not have any significant influence on the hemolysis of erythrocytes. These experimental findings show that the hemolysis caused by interaction between emulsions and erythrocytes was dependent on the PC content of both the emulsifying agent used and the erythrocyte membrane, and that the SM present in the erythrocyte membrane was an essential component for the stability of erythrocytes against emulsion-induced hemolysis.