Effect of High Calcium and Phosphate Concentrations on the Physicochemical Properties of Two Lipid Emulsions Used as Total Parenteral Nutrition for Neonates

Abstract

Premature infants require protein and energy for their growth and an adequate intake of calcium and phosphorus for their bone formation. However, several factors can affect the stability of intravenous lipid emulsions intended to be administered as neonatal total parenteral nutrition. This study evaluated the effect of additives and various concentrations of both calcium gluconate and glucose-1-phosphate on two intravenous lipid emulsions (Clinoleic® 20% and Ivelip® 20%) when using Primene® 10% as source of amino acids and simulating clinical conditions (24-h storage at 37 °C). Two series of experiments for each lipid emulsion were carried out. One used separate ingredients (water, glucose, or amino acids) with various calcium phosphate concentrations; and the second included total parenteral nutrition admixtures with varied amino acid (1%, 2%, or 3.5%) and glucose (8% or 14%) concentrations. Evaluation was performed by visual and microscopic examination and pH, particle size, and zeta potential measurements. Calcium concentrations were determined before and after filtration by atomic absorption spectroscopy. Samples were stored 24 h at 37 °C. Investigations of lipid–nutrient admixtures showed a significant decrease of the pH with Primene® and a visual instability when mixing with sterile water alone, while total parenteral nutrition admixtures made of Clinoleic® 20% or Ivelip® 20% were stable regarding pH, particle sizing, and zeta potential after storage conditions. Samples containing only calcium have their zeta potential charge reduced compared to samples containing both calcium and phosphate. Also, the evaluation of calcium phosphate solubility showed a significant decrease of the calcium concentration after filtration of the samples. Our data indicated that total parenteral nutrition admixtures could contribute to protect the lipid emulsion from its physicochemical degradation and that using organic phosphate with calcium gluconate has a less deleterious effect than using calcium alone with total parenteral nutrition. Also, the use of inline filters remains necessary for good protection from hazards of precipitates during the administration of total parenteral nutrition regimens.