Influence of the type of amino acids in the formation of precipitates of copper and sulphur in parenteral nutrition.

Abstract

Objective: we found a black precipitate during the infusion of a parenteral nutrition without lipids. The objective of this study is to check the composition of the precipitate and the influence of the type of amino acids in its formation. Methods: four PN bags were prepared with the following composition: 1 l of amino acids solution, 150 g glucose, 60 mEq potassium, 217 mEq chloride, 105 mEq sodium, 15 mEq magnesium, 15 mEq calcium, 18.63 mmol phosphorus and trace elements (Addamel®). Each bag was prepared using a different type of amino acids solution with different amount of cysteine per litre: Tauramin® 10% (0.5 g/l), Primene® 10% (1.89 g/l), Tauramin® 12.6% (0.62 g/l) or Synthamin® 10% (0 g/l). Tauramin® 10% and Primene® 10% were packaged in glass containers whereas Tauramin® 12.6% and Synthamin® 10%, in plastic. The contents of each bag were filtered using Pall NEO96E 0.2 micron filters. A 2.25% area of each filter was observed by scanning electron microscopy at 100x magnification. The analysis by energy dispersive spectroscopy (EDS) was performed at 1,000x magnification. Results: in the Primene® 10% and Tauramin® 10% filters, a greater amount of precipitate was observed than with Tauramin® 12.6% and Synthamin® 10%. The percentage of copper and sulphur in each area of the filters studied was, respectively, 22.9% and 11.5% (Primene® 10%), 19.3% and 9.6% (Tauramin® 10%), 3.7% and 0% (Tauramin® 12.6%), 2.5% y 0% (Synthamin® 10%). Conclusions: the observed precipitate contains copper and sulphur. Precipitate formation occurs in high cysteine content amino acids solutions packaged in glass containers. It is important to use filters in the administration of PN to ensure that this type of precipitates are retained and do not pass to the patient. Key words.