Stability of Intravenous Fat Emulsions

To the Editor.—Recently, Black and Popovich reported on the stability of the liposomes of a 10% fat emulsion (Intralipid) in various mixtures with carbohydrates, amino acids, and electrolytes (Archives 1980;115:891). By means of an electronic RBC counter and a light microscope equipped with a hemocytometer, they evaluated the fat particle size distribution (PSD) and found that changes in the PSD of the emulsion reflect globule coalescence and therefore indicate loss of emulsion stability. No change in PSD for 72 hours was seen in mixtures with amino acids up to 8.5%. Contact with carbohydrate solution exceeding 5% led to a distinct coalescence of fat globules and, therefore, to instability within 24 hours. It was further noted that amino acid solutions could cancel this effect for a period up to 72 hours. The authors thought that the amino acid solution buffers the low pH of carbohydrates and therefore hinders the deterioration