Fat emulsion particle-size distribution in total nutrient admixtures

Area of Science:

• Parenteral Nutrition
• Pharmaceutical Sciences
• Physical Chemistry

Background:

• Lipid emulsions are crucial components of total nutrient admixtures (TNAs) for parenteral nutrition.
• Understanding the physical stability of these emulsions is vital for safe and effective clinical use.
• Commercial lipid emulsions like Intralipid and Liposyn II are commonly used but may exhibit different behaviors in TNA formulations.

Purpose of the Study:

• To evaluate the fat particle-size distribution and physical stability of two commercial lipid emulsions (Liposyn II and Intralipid).
• To assess how these properties change before and after incorporation into total nutrient admixtures (TNAs), with and without electrolytes.
• To determine the impact of storage conditions on the stability of these TNA formulations.

Main Methods:

• Preparation of four TNAs without electrolytes and four with electrolytes, using both Liposyn II and Intralipid.
• Measurement of fat particle sizes using photon correlation spectroscopy (< 1 micron) and light blockage (2-60 microns).
• Storage of admixtures at 4°C for 2-9 days, followed by 1 day at 25°C to simulate various conditions.

Main Results:

• Intralipid had a larger mean particle size (374 nm) compared to Liposyn II (313 nm) in the < 1-micron range.
• Electrolyte-containing admixtures showed a ~7% decrease in mean particle size.
• Intralipid admixtures had significantly more particles > 2 microns than Liposyn II admixtures; electrolyte addition increased particle counts for Liposyn II.

Conclusions:

• Both Intralipid and Liposyn II demonstrated overall stability in TNAs regarding pH and visual appearance.
• Electrolyte presence influenced the particle size distribution and stability dynamics of the two lipid emulsions differently.
• Further investigation into specific interactions between lipid types and electrolytes in TNA formulations is warranted for optimal clinical application.