Physicochemical stability of intravenous lipid emulsions as all-in-one admixtures intended for the very young

Background & aims: Intravenous lipid emulsions (IVLEs) are unstable when growth of lipid droplets into large fat globules is detected by appropriate particle sizing techniques. Specifically, instability is evident when the volume-weighted percent fat (PFAT)>5 μm exceeds 0.4% of the total lipids present. This represents an approximate 10-fold increase in the population normally present in the large-diameter tail of stable lipid emulsions. The composition of the oil phase of an IVLE, however, has been shown to exhibit different stability characteristics. We investigated the stability of various IVLEs containing physical mixtures of medium-(MCT) and/or long-chain triglycerides (LCT) in three different all-in-one (AIO) admixtures intended for neonatal and infant patients. Methods: The 20% (w/v) IVLEs used in this study were composed of the following oils (by weight): 1) 1 : 1—soybean/safflower (SS); 2) 1 : 1—MCT:soybean (MS); and 3) 5 : 4 : 1—MCT:soybean:fish (MSF). Stability was assessed by light obscuration or light extinction to count large fat globules, and by aided (microscopic) and unaided (naked eye) visual assessments for up to 48 h at room temperature. Results: The stability of SS-based admixtures significantly and rapidly deteriorated in one of the three AIO compositions studied, whereas the AIOs made from MS or MSF were stable for all formulations. Conclusion: The results suggest that AIOs made from MCT/LCT-containing IVLEs are more stable than those made from pure LCTs.