Lipid globule size in total nutrient admixtures prepared in three-chamber plastic bags

Purpose. The stability of injectable lipid emulsions in three-chamber plastic (3CP) bags, applying the globule-size limits established by United States Phormacopeia (USP) chapter 729, was studied. Methods. A total of five premixed total nutrient admixture (TNA) products packaged in 3CP bags from two different lipid manufacturers containing either 20% soybean oil or a mixture of soybean oil and medium-chain-triglyceride oil as injectable lipid emulsions were tested. Two low-osmolarity 3CP bags and three high-osmolarity 3CP bags were studied. All products were tested with the addition of trace elements and multivitamins. All additive conditions (with and without electrolytes) were tested in triplicate at time 0 (immediately after mixing) and at 6, 24, 30, and 48 hours after mixing; the bags were stored at 24-26 degrees C. All additives were equally distributed in each bag for comparative testing, applying both globule sizing methods outlined in USP chapter 729, Results. Of the bags tested, all bags from one manufacturer were coarse emulsions, showing signs of significant growth in the large-diameter tail when mixed as a TNA formulation and failing the limits set by method II of USP chapter 729 from the outset and throughout the study, while the bags from the other manufacturer were fine emulsions and met these limits. Of the bags that failed, significant instability was noted in one series containing additional electrolytes. Conclusion. Injectable lipid emulsions provided in 3CP bags that did not meet the globule-size limits of USP chapter 729 produced coarser TNA formulations than emulsions that met the USP limits.