The effect of Na benzoate on serum bilirubin of the Gunn rat

The administration of Na benzoate to grown and suckling Gunn rats in single doses of 7 and 35 mg/kg failed tosignificantly alter serum bilirubin concentrations. These doses are comparable to quantities of Na benzoate contained in injectable diazepam used therapeutically for newborn infants. Repeated doses of 7 mg/kg in the grown rat showed no effect, as well. A single dose of 100 or 200 mg/kg of Na benzoate and repeated doses of 35 mg/kg resulted in depressed serum bilirubin concentrations. The higher concentrations of Na benzoate, however, greatly exceed amounts contained in doses of diazepam recommended for clinical use in the human neonate. The data suggest that the use of injectable diazepam, in appropriate quantities, poses no hazard to the newborn infant in terms of bilirubin toxicity. The greater affinity for bilirubin of human albumin, than that of rat albumin, may further minimize the risk.