The effect of surface charge on the physical properties of intravenous lipid emulsions during steam sterilization
Abstract
Lipid emulsions are used for intravenous nutrition and as carriers for drugs. The droplet size must be very small in order not to block capillaries which are no larger than 5 μ. Lipid emulsion with a required droplet size can be produced by using a Microfluidizer. The lipid emulsions must be sterilized by autoclaving. Exposure to the high temperature (121°C) required for autoclaving causes coalescence and an increase in droplet size. The purpose of this study is to investigate whether an increase in the electrostatic repulsive force between oil droplets by formulation modification improved the thermal stability of lipid emulsion during autoclaving. It was found that increasing the negative surface charge on the droplets by adding an anionic surfactant to the basic formula protects the emulsion from coalescence during autoclaving. The addition of sodium cholate or sodium oleate improved the thermal stability of the emulsion but could not completely prevent coalescence during autoclaving. However, the addition of a small amount (6.6 × 10-4 or 13.2 × 10-4 m) of purified anionic phospholipid fractions (phosphatidic acid, phosphatidylglycerol, or phosphatidylinositol) produced emulsions which exhibit no change in droplet size during autoclaving. The modified emulsions did not exhibit any change in droplet size after storage for one month at 4, 25, and 40°C. The reduction of the negative surface charge of the oil droplets in the lipid emulsion by adding stearylamine confirmed that the surface charge was an important factor in stabilizing emulsions during autoclaving as the emulsions having a smaller negative surface charge separated into two phases during autoclaving.
Degree
Ph.D.
Advisors
Hem, Purdue University.
Subject Area
Pharmaceuticals
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