Drug-induced displacement of bilirubin from albumin in the newborn.

Kernicterus is probably caused by precipitation of insoluble bilirubin acid in brain cells. The pigment is transferred from blood plasma to cells. The tendency for precipitation depends upon the ratio of unconjugated plasma bilirubin concentration to the concentration of reserve albumin for binding of bilirubin and is increased when part of the albumin is occupied by competitive binding of a drug. Laboratory methods are available whereby it is possible, on certain well-defined presumptions, to measure this drug effect in quantitative terms. Measurements can be made in systems with pure albumin as well as in plasma samples from treated patients. It would thus appear feasible at the present stage to establish a basis for official testing of the bilirubin-displacing effects of drugs.