High particle counts in neonatal parenteral nutrition solutions with added cysteine: Relationship to crystal formation and effect of filtration on cysteine content.

Background: Parenteral nutrition(PN) solutions containing calcium gluconate and cysteine have elevated particle counts when analyzed using laser light obscuration (LO) as recommended by the United States Pharmacopeia. It is unclear whether increased particle formation in these solutions results in decreased availability of cysteine to neonatal patients due to filtration.
Objective: The purpose of this study was to measure cysteine concentrations in neonatal PN solutions before and after filtration as well as analyze precipitates on filters.
Methods: Solutions of PN containing amino acids with and without cysteine that were compounded with calcium chloride or calcium gluconate plus potassium phosphate were analyzed using LO. Concentrations of cysteine were measured before and after filtration. The effect on particle formation of magnesium sulfate (MgSO ₄ ) and D70 was also evaluated.
Results: Multiple additives including the specific calcium or D70 additive, cysteine, and MgSO ₄ influenced particle formation of particles detected using LO. There was no significant decrease in cysteine concentration because of filtering and there was no difference in the amount of calcium on filters of various solutions after filtration regardless of LO particle counts. Scanning electron micrographic (SEM) analysis found no significant differences in crystal composition. Light microscopic and SEM examination did not show evidence of high particle counts on filters.
Conclusion: The increased particle counts detected in neonatal PN solutions containing cysteine added at the time of compounding does not appear to result in increased precipitate or crystal formation. It is not associated witha decrease in cysteine delivery to patients.
(© 2021 American Society for Parenteral and Enteral Nutrition.)