Emulsion stability in a total nutrient admixture for total parenteral nutrition

A total parenteral nutrition solution containing lipid was tested up to 28 days at 4 degrees C followed by an additional 2 days at 22 degrees C (room temperature) for stability of the emulsion. The total nutrient admixture (TNA) contained 1000 ml 10% FreAmine, 1000 ml 50% dextrose, 500 ml 10% Soyacal, electrolytes, vitamins and trace elements. Stability was determined by direct observation, light and electron microscopy, Coulter counter, pH, osmolality, and fatty acid profile. Samples were tested when fresh at 0 hours, after 2 days at 22 degrees C, 14 days at 4 degrees followed by 2 days at 22 degrees C, and 28 days at 4 degrees C followed by 1 and 2 days at 22 degrees C. Light microscopy measured particles greater than 2 microns in diameter; 99% of these particles were less than 6 microns, with no increase with time. Electron microscopy found that lipid particle size increased slightly up to 30 days, at which time the mean diameter was 0.36 +/- 0.01 micron. Coulter counter studies found that lipid droplet diameter increased while at 22 degrees C; however, on day 30, 99% of the particles were less than 1.97 microns. Mean pH and osmolality were 6.35 +/- 0.04 and 1880 +/- 14.5 mOsm/kg, respectively, with no change over time. Analysis of fatty acids by gas chromatography showed that fatty acid profiles and amounts of triglyceride, phospholipid and total lipid did not change. Thus, the emulsion in the TNA was stable for 28 days refrigeration, followed by 2 days at room temperature.