Practical aspects of lipid emulsion stability and peroxidation processes in parenteral nutrition

Abstract

The stability of lipid emulsions used in parenteral nutrition (PN) is a key determinant of both the safety and effectiveness of intravenous nutritional therapy. This review summarizes the main physicochemical factors influencing the stability of ternary PN admixtures, emphasizing the role of electrolytes, pH, osmolarity, temperature, light exposure, and handling during storage and administration. Mechanisms leading to emulsion destabilization-such as lipid globule coalescence or phase separation-are described, highlighting the importance of maintaining a mean particle diameter below 5 µm to prevent fat embolism and other clinical complications. Lipid emulsions are particularly prone to oxidative degradation through lipid peroxidation, resulting in the generation of toxic compounds with potential clinical impact. This article also examines lipid peroxidation processes during storage and infusion, identifying the main promoting factors, including exposure to light, high temperature, lipid composition, and the presence of pro-oxidant trace elements. Understanding and controlling these mechanisms are essential to preserve the integrity and clinical safety of PN admixtures. The proper formulation, manipulation, and storage of lipid emulsions-through photoprotection, oxygen limitation, and use of multilayer bags-are fundamental measures to ensure their physicochemical stability and minimize risks associated with lipid degradation.