Calcium Chloride and Calcium Gluconate in Neonatal Parenteral Nutrition Solutions with Added Cysteine: Compatibility Studies Using Laser Light Obscuration Methodology

Background Parenteral nutrition (PN) solutions containing calcium gluconate (CaGlu) and cysteine have elevated particle counts when analyzed using laser light obscuration (LO) as recommended by the United States Pharmacopeia (USP). There are no compatibility studies for solutions compounded with cysteine and containing calcium chloride (CaCl2) using LO. The purpose of this study was to conduct compatibility testing for neonatal PN solutions containing CaCl2 and CaGlu with cysteine. Methods Solutions of amino acids (2.5%), containing either CaCl2 or CaGlu plus potassium phosphate, were compounded with 50 and 100 mg/dL cysteine. Solutions were analyzed for particle counts using LO. Maximum concentrations tested were 20 mmol/L calcium and 15 mmol/L phosphate. Three solutions containing CaCl2 (144 total solutions) and 2 containing CaGlu (96 total solutions) and the same concentration of additives were compounded. If the average particle count of replicates exceeded USP guidelines, the solution was incompatible. Results All solutions containing CaGlu had particle counts that exceeded USP guidelines for particle counts ≥10 μm (range, 86–580 particles/mL). For CaCl2, 90 of 144 solutions were compatible (range of particle counts for all solutions, 3–121 particles/mL). Maximum compatible concentrations of CaCl2 and potassium phosphate were 15 mmol/L and 12.5 mmol/L, respectively, for solutions containing both 50 and 100 mg/dL cysteine. Conclusion This study found that neonatal PN solutions containing CaGlu with added cysteine have significantly higher particle counts, exceeding USP guidelines for compatibility, than those containing CaCl2.