The effect of paraben preservatives on albumin binding of bilirubin.

The interaction of methylparaben and propylparaben with bilirubin-albumin complexes was studied using difference spectra, Sephadex gel filtration, red blood cell uptake of bilirubin, and the peroxidase assay. Methylparaben was found to be a weak competitor with bilirubin for binding to primary albumin-binding sites but a strong binding competitor (similar to sulfisoxazole) at secondary sites. The displacing effects of methylparaben and sulfisoxazole were additive. Propylparaben bound to albumin but did not displace bilirubin. Drugs and injectable saline and water preparations which contain methylparaben should be avoided in jaundiced newborn infants when the high-affinity albumin-binding sites approach saturation.