ADMIXTURE OF A MULTIVITAMIN PREPARATION TO PARENTERAL-NUTRITION - THEMAJOR CONTRIBUTOR TO IN-VITRO GENERATION OF PEROXIDES

Background. Peroxides have been reported to contaminate lipid emulsion s and amino acid solutions used in total parenteral nutrition (TPN). T his is particularly disturbing in newborn infants who are prone to sev eral diseases related to immature defense mechanisms against oxidative challenges. It is not clear whether the antioxidants in multivitamins help protect parenteral nutrients against the hazards of oxidation. O bjective. To evaluate the role of a multivitamin preparation (MVI) on the actual peroxide load received by patients on TPN. Methodology. The generation of peroxides in parenteral nutrition was tested first usin g test solutions. We compared the relative contribution of commerciall y available amino acid solutions, a lipid emulsion, and MVI on the lev el of peroxides in clinically relevant TPN solutions. Second, we measu red the level of peroxides actually infused at the bedside. In both ci rcumstances, the effects of time and light exposure were isolated. The level of peroxides was determined by a colorimetric technique and exp ressed as mu M equivalents tert-butyl hydroperoxide (mu M = TBH). Resu lts. Even when protected from light, the addition of MVI produced a 10 -fold increase in peroxides (mean +/- SEM, n = 3, 19 +/- 4 to 189 +/- 8 mu M = TBH at 4 h) in the fat-free TPN solution and a fourfold incre ase (64 +/- 6 to 244 +/- 8 mu M = TBH at 4 h) in the lipid-containing TPN solution. A dose-response relationship was found between the conce ntration of MVI and peroxide levels. The effect of light was the stron gest in the presence of multivitamins. The amino acid solutions had a relative inhibitory effect on the generation of peroxides by MVI, whic h varied (from 54 +/- 1% to 72 +/- 1%) all according to the amino acid blend. In parenterally fed premature infants, protecting the intraven ous set from light decreased the load of infused peroxides (146 +/- 15 vs 215 +/- 24 mu M = TBH). Conclusions. The lipid emulsion had a sign ificant but minor additive effect compared with the multivitamin prepa ration, which was the major contributor to the generation of peroxides , Protection from photooxidation is not sufficient to prevent peroxida tion of TPN solutions. Contrary to what one would expect, increasing t he concentration of MVI will lead to a greater generation of peroxides , suggesting that the essential antioxidants in MVI do not have antipe roxide properties.