Parenteral Nutrient Admixtures as Drug Vehicles: Theory and Practice in the Critical Care Setting

Abstract

Parenteral nutrient (PN) admixtures are the most complex, extemporaneously compounded formulations routinely prepared for hospitalized and home-based patients. In addition, drugs are added with increasing frequency to PN admixtures, thus presenting even greater physicochemical challenges to this highly complex pharmaceutical product. The continuous infusion of selected drugs may provide pharmacokinetic and therapeutic advantages over conventional, intermittent, bolus methods of administration. Fluid conservation, cost savings, and a possible decrease in the risk of infection through reduced catheter manipulation and simplification of therapy provide additional incentives to consider the use of PN admixtures. The many advantages of PN admixtures make them an attractive approach to cost-effective care, with special clinical benefits achieved in the critical care setting. This article reviews our clinical experience using PN admixtures as drug vehicles for selected drugs and presents some theoretical as well as actual benefits associated with this practice.

A.S.P.E.N. Clinical Guidelines

“…Any medications considered should be limited to IV drugs with stable regimens, which are therapeutically effective by continuous infusion and do not require dose titration. 111 Nearly 75% of respondents in a national survey allow nonnutrient medication to be added to PN admixtures. 112 Most frequently included are insulin, heparin, and the histamine type-2 receptor antagonists.…”

“…[114][115][116] Therefore, including non-nutrient medication in PN admixtures is risky in the absence of appropriate evidence indicating compatibility and stability. 111 Specific criteria for evaluating compatibility and stability studies of medication in PN are well recognized and should be met. 111,117 Any potential for incompatibility or instability as a result of physical-chemical interaction poses a safety concern.…”

Parenteral Nutrition in Neonatus and Compatibility Issues: a Review Article

“…Stability is also dependent on the source of the TGs, the amino acid pattern, the glucose content (viscosity), the electrolyte and trace element concentration, and the pH. In a pH range of 5-8, the negatively charged phosphate moiety of the emulsifier prevents coalescence of the small oil droplets (250-500 nm diameter) by electric repulsion [101].…”

“…The two general sources of these complications are catheterrelated infection and solution-infusate contamination. The risk of catheter-related bloodstream infection remains one of the most serious complications associated with PN [101]. Temporary or short-term central venous catheters account for about 90% of nosocomial blood stream infections, and only 10% of infections are from long-term devices such as tunneled catheters or implanted reservoirs [102].…”

“…The variety of PN regimens and of drug dosages is huge. Therefore, pharmaceutical expertise is mandatory for safe and effective treatment [88,101,102].…”