ANTIPEROXIDE ACTIVITY OF SODIUM METABISULFITE - A DOUBLE-EDGED-SWORD

Sulfites are chemical substances that are used widely in the pharmaceu tical industry to reduce or prevent oxidation. Sodium metabisulfite (N a2S2O5) is still present in several parenteral amino acid solutions. S ince intravenous lipid emulsions are contaminated by hydroperoxides, w e evaluated whether metabisulfite had an antioxidant activity against hydroperoxides. In vitro, Na2S2O5 inhibited the oxidant activity of H2 O2, tert-butyl-, and cumene hydroperoxides. The antioxidant capacity o f metabisulfite was supported in vivo by the lower (P < 0.01) excretio n of malondialdehyde, a stable end product of lipid peroxidation, in b abies receiving metabisulfite in their parenteral nutrition. However, for concentrations outside the range found in solutions for parenteral nutrition, the reduction of hydroperoxides by Na2S2O5 could transform this compound into an oxidant, like a sulfite radical. It is suggeste d that metabisulfite has antiperoxide properties that, under specific conditions, contribute to the generation of toxic oxidants.