Calcium and phosphate solubility in neonatal parenteral nutrient solutions containing Aminosyn PF.

Factors affecting the solubility of calcium and phosphate in neonatal total parenteral nutrient (TPN) solutions containing a new amino acid formulation were studied. Six TPN solutions containing various concentrations of Aminosyn PF, an amino acid solution for infants and children, were prepared in 10% dextrose injection. Some of the solutions also contained cysteine hydrochloride 40 mg per gram of protein. Various concentrations of calcium gluconate and monobasic and dibasic potassium phosphate were added to 20-mL samples of the TPN solutions. A total of 27 samples of each TPN solution was prepared. Samples were visually inspected after 18 hours at 25 degrees C and again after 30 minutes in a water bath at 37 degrees C. Clear samples at this time were also examined microscopically. Solubility curves were prepared by plotting the concentrations at which either visual or microscopic precipitation occurred. Solubility curves for TPN formulations containing Aminosyn PF revealed a decrease in calcium solubility of 5 to 15 meq/L and a decrease in phosphate solubility of 5 to 15 mmol/L compared with previously published calcium-phosphate solubility curves for another similar amino acid solution, TrophAmine. Calcium and phosphate solubilities were also influenced by temperature and the time after solution preparation. In these TPN formulations containing Aminosyn PF as the amino acid source, the solubilities of calcium and phosphate were substantially less than reported in a previous study of solutions containing TrophAmine.