Folic Acid and Total Parenteral Nutrition

Abstract

The stability of folic acid in a variety of solutions used for parenteral nutrition has been determined over a 2-wk period. Provided that the acidity of the solution remains above pH 5.0 the folate, in the concentrations usually used for parenteral nutrition, will remain stable in solution, and all of the folate added to the solution will be delivered to the patient. The applicability of this in vitro work to a group of patients requiring parenteral nutrition was assessed, in order to determine a suitable dose. A dose of 0.2 mg of folic acid daily was inadequate to meet the requirements of these patients. In contrast a dose of 1.2 mg daily for 7 days was sufficient to cause an increase in the serum folate concentration.

Storage of Mixtures for Total Parenteral Nutrition Iii. Stability of Vitamins in TPN Mixtures

“…Optimal p H stability seems to be around 7, but the values found in the literature vary (32). If a solution has a p H lower than 5.0, folic acid may precipitate ( 19).…”

“…Thiamine is stable in some amino acid solutions (lo), but may degrade in the presence of bisulphite (16,17). When mixed with parenteral nutrition solutions the availability of folic acid may be impaired (18,19). Ascorbic acid is stable in some parenteral nutrition solutions (171, while it is shown to degrade in solutions containing trace elements (1 0,15).…”

A review of stability issues associated with vitamins in parenteral nutrition

“…There has been a suggestion by Lee et al 49 that adsorption of folic acid onto polyvinylchloride (PVC) infusion bags may occur and was responsible for a 33% loss seen after 42 days of storage. However, later studies have found the vitamin to be compatible with PN bags 11,48 .…”

“…Folic acid injections are usually formulated at a pH in excess of 8.0 because the vitamin is prone to precipitation at lower pHs 47 . One investigation examined the effect of pH on folic acid precipitation and found that if the pH remains above 5.0, folic acid remains in solution 48 . As PN usually has a pH of between 5.0-6.0, folic acid should not precipitate.…”

Compatibility and Stability of TPN Mixtures in Big Bags

“…After addition to T P N mixtures, there is a danger of free folate precipitation. Barker et al (54) have recently reported that folic acid is stable and remains in solution in T P N mixtures provided the pH remains above 5.0. Folic acid may be added to Synthamin or Freamine 11-containing mixtures which can be stored at 2 4 C for 14 days without any evidence of precipitation.…”