Physicochemical properties and hemolytic effect of different lipid emulsion formulations using a mixture of emulsifiers

The purpose of this study was to elucidate the influence of ternary mixtures of different emulsifiers on the physicochemical properties of lipid emulsions by the aid of simplex lattice design with constraints. The physicochemical properties and the stability during the autoclaving process, as a consequent result, were investigated by examining the changes in particle size, zeta potential, and cloud point. The emulsifiers chosen were lecithin, Synperonic F68 and Tween 80. In addition, their potential for hemolysis was evaluated as it may serve as an in vitro toxicity screening method. The formulations with only Tween 80 as an emulsifier showed a noticeable change in the particle size during autoclaving as well as a remarkable erythrocyte membrane damage. In contrast, phospholipids and Synperonic F68 formulations displayed good stability during autoclaving and showed almost no hemolytic activity. Moreover, mixing Tween 80 with either lecithin or Synperonic F68 improved the stability of these formulations during the autoclaving process. Simultaneously, this led to a remarkable decrease in the hemolytic effect. This observation could be partially correlated with the cloud point, which increased by adding lecithin and was less influenced by adding Synperonic F68. This in turn resulted in an increase in the surface charge, when lecithin was added. This results in a higher resistance of the emulsifier complex to dehydration producing a more stable emulsifier film around the oil droplets. These factors inhibited the flocculation of the emulsifiers and could hinder the coalescence of the oil droplets during the autoclaving process.