STABILITY OF TPN MIXTURES COMPOUNDED FROM LIPOFUNDIN-S AND AMINOPLEX AMINO-ACID SOLUTIONS - COMPARISON OF LASER DIFFRACTION AND COULTER-COUNTER DROPLET SIZE ANALYSIS

We have studied the stability of a range of total parenteral nutrition (TPN) mixtures compounded from Lipofundin S and Aminoplex amino acid solutions. Droplet size was studied for 180 days using both light scattering and electrical zone sensing techniques; additionally, the chemical stability was monitored via the pH and osmolality of the mixtures. All the mixtures were stable for 90 days, but some irreversible flocculation was observed in all after 180 days. This appeared to be due to the prolonged storage of the bags in one position, and suggested that TPN mixture stability could be enhanced by occasional remixing of creamed droplets. The Coulter counter was able to detect the gradual formation of oil droplets larger than 1-mu-m in diameter, while the laser diffraction instrument was less sensitive to these droplets until significant coalescence had occurred by day 180. The results demonstrate the value of single particle zone sensing techniques for the study of TPN mixture stability.