Supplementation of total parenteral nutrition solutions with ferrous citrate

Technical aspects of trace element supplementation

Routine supplementation of total parenteral nutrition mixtures with the readily available single or combination trace elements products is becoming more widespread. As more is learned about deficiency syndromes and monitoring techniques, so too must we understand more about the physicochemical interactions between individual trace elements and other nutrients, that could ultimately affect bioavailability. Expert pharmaceutical assessment of these complex reactions, that have been demonstrated to occur in solution, becomes increasingly important in order to optimize the efficacy of micronutrient therapy.

Compatibility and stability of additives in parenteral nutrition admixtures

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.

Bound iron admixture prevents the spontaneous generation of peroxides in total parenteral nutrition solutions

BACKGROUND

Parenteral administration of iron is a matter of controversy because it is feared that it could contribute to oxidative reactions. The aim of this study was to verify if irondextran participates in the redox reactions occurring in total parenteral nutrition (TPN) solutions.

METHODS

Irondextran was compared with different forms of iron in the interaction with peroxides. Hydroperoxide levels were measured by a colorimetric technique in TPN solutions, in presence of varying sources (FeCl2, FeSO4, irondextran, iron sorbitol) and concentrations (0-0.8 mM) of iron. The consumption and inhibition of peroxide generation were tested by analyzing the effect of iron on different sources of peroxides (H2O2, tert-butyl and cumen hydroperoxide). The free radicals produced under conditions of a Fenton-like reaction were measured by the oxidation of scopoletin. And the proportion of Fe3+ freed by both bound-iron sources was counted by measuring the masking effect on the thiol function of cysteine.

RESULTS

Free-iron admixture to parenteral nutrition induces the formation of free radicals, whereas sources of bound-iron inhibit the generation of peroxides in parenteral nutrition without implying a Fenton-like reaction.

CONCLUSION

For patients requiring iron supplementation, bound-iron should be added during the preparation of TPN solutions, because it protects against the spontaneous generation of peroxides.

Trace elements in parenteral micronutrition

OBJECTIVE

To update some essential trace metals required in total parenteral nutrition.

CONCLUSION

Essential trace metals, chromium, copper, manganese, molybdenum, selenium, and zinc are added to parenteral fluids to prevent the development of deficiency syndromes. When possible, these metals should be monitored, even in patients on short-term total parenteral nutrition (TPN) to avoid deficiency or toxicity. Many of the nutrients or additives used in parenteral solutions may be contaminated with metals, such as aluminum or chromium. Such trace-metal monitoring becomes more critical in infants, and those on long-term TPN.

Issues in Contemporary Drug Delivery: Part V: Total Parenteral Nutrition

Objective:

To provide an overview of common compounding and administration guidelines for total parenteral nutrition (TPN). The compatibility of various drug products with TPN preparations is also discussed.

Data Sources:

References were selected from published bibliographies of specialized nutrition and drug-nutrient interaction articles, package inserts and manufacturer's information, and specific topic searches in MEDLINE computerized database (English language, through 1989).

Study Selection:

Studies that investigated stability were selected preferentially to those studying compatibility alone; when stability data were not available, compatibility studies were included. Studies using products marketed in the US were chosen preferentially to those using European products; studies and case reports using human subjects were selected in preference to animal studies. Sixty percent of the initially identified studies were selected for inclusion.

Data Extraction:

Studies were reviewed by the authors for internal consistency and statistical validity.

Data Synthesis:

Intravenous solutions can be manufactured to meet various nutritional specifications. As additional nutrients and drugs are incorporated, the risk of incompatibility and instability of the admixture increases. Stability data are relatively sparse, leading to a dependence on compatibility studies for decision making.

Conclusions:

A wide variety of TPN formulations can be compounded to meet the individual needs of patients of all ages and assorted disease states. Addition of specific drugs to the TPN preparation may improve the efficiency of drug delivery and improve overall therapeutic response. Care must be taken, however, to ensure that incompatible compounds are not combined in a single TPN preparation.

Parenteral iron dextran therapy

Parenteral iron therapy is indicated in patients with iron-deficiency anemia associated with conditions that interfere with the ingestion or absorption of oral iron. Replacement doses of iron required to replenish iron stores are based on body weight and the observed hemoglobin value. Methods of administering iron dextran are reviewed, including intramuscular and intravenous injections of the undiluted drug, intravenous infusion of a diluted preparation, and as an addition to parenteral nutrition solutions. The overall incidence of adverse reactions associated with the parenteral administration of iron is low, but the potential for an anaphylactic reaction requires that an initial test dose be given followed by careful patient observation.

Total parenteral nutrition in children

This article first focuses on the indications for total parenteral nutrition and the effect of its use on the outcome of various nutrient-depleting diseases in infants and children. This is followed by a discussion of some of the newer nutrient additions to total parenteral nutrition regimens, such as biotin, carnitine, zinc, copper, iron, and others.