Parenteral nutrition. Pharmaceutical problems of compatibility and stability.

A typical All-in-One (AIO) parenteral nutrition mixture in a 3-litre polymeric infusion bag will consist of lipid emulsion, amino acids, glucose, electrolytes, trace elements and vitamins. This varied mixture of chemical entities provides the potential for a number of chemical and physicochemical interactions that can compromise the clinical safety and efficacy of the product. The destabilisation of the lipid emulsion in the presence of electrolytes is a major problem. Although a predictive equation for the maximum concentrations of mono-, di- and trivalent ions causing instability has been proposed, it is too simplistic to be of significant value. The reasons for this are discussed as well as the stability implications of other additives to the parenteral nutrition mixture.