Allwood M C, Kearney M C
Medicines Research Unit, University of Derby, Mickleover, United Kingdom.
Nutrition. 1998 Sep;14(9):697-706. doi: 10.1016/s0899-9007(98)00063-x.
The addition of additives (electrolytes, trace elements, and vitamins) to parenteral nutrition (PN) mixtures can lead to precipitation as a result of physical incompatibilities and can lead to chemical degradation of individual ingredients. The most significant cause of precipitation is excessive concentrations of calcium phosphate. The most significant cause of chemical instability is the oxidation of specific vitamins. The factors influencing calcium phosphate solubility include the commercial amino acid source, the calcium and phosphate salts used, temperature, magnesium concentration, and final volume. Precipitation can be avoided by organic phosphates. Trace element precipitation is most commonly caused by the formation of iron phosphate salts or copper cysteinate in cysteine-containing amino acid infusions. The least stable nutrient is ascorbic acid, which reacts with oxygen, and is catalyzed by copper ions. Oxygen originates from PN ingredients, the filling process, air remaining in the bag after filling, and oxygen permeation through the bag wall. Storage in multilayered bags with reduced gas permeability can protect residual ascorbic acid. Other chemical losses are caused by the reduction of thiamine by metabisulfite, and photodegradation of daylight-sensitive vitamins, especially retinol and riboflavin, during administration.
在肠外营养（PN）混合液中添加添加剂（电解质、微量元素和维生素）可能会因物理不相容性导致沉淀，并可能导致个别成分的化学降解。沉淀的最主要原因是磷酸钙浓度过高。化学不稳定性的最主要原因是特定维生素的氧化。影响磷酸钙溶解度的因素包括商业氨基酸来源、所用的钙盐和磷酸盐、温度、镁浓度以及最终体积。有机磷酸盐可避免沉淀。微量元素沉淀最常见的原因是在含半胱氨酸的氨基酸输注中形成磷酸铁盐或铜半胱氨酸盐。最不稳定的营养素是抗坏血酸，它会与氧气反应，并由铜离子催化。氧气来源于PN成分、灌装过程、灌装后袋中残留的空气以及氧气透过袋壁。储存在透气性降低的多层袋中可以保护残留的抗坏血酸。其他化学损失是由偏亚硫酸氢盐使硫胺素还原以及在给药过程中对光敏感的维生素（尤其是视黄醇和核黄素）的光降解引起的。
