Twenty full-term newborns given phenobarbital 8 mg/kg/day for the first four days of life had significantly lower concentrations of serum indirect bilirubin than a group of 20 control infants by the fourth and fifth day of life. Similarly, ten infants with elevated serum indirect bilirubin levels treated from the fifth to ninth day showed significantly lower values by day 10 than controls. In vivo glucuronidation studies using salicylamide as the substrate showed a more pronounced average increase in the glucuronide fraction between the fifth and tenth day of life in ten infants pretreated with phenobarbital as compared to a group of 14 controls, suggesting that the effect of phenobarbital in reducing serum bilirubin levels is mediated, at least in part, by enhanced glucuronide formation.
Stern L, Khanna NN, Levy G, Yaffe SJ. Effect of Phenobarbital on Hyperbilirubinemia and Glucuronide Formation in Newborns. Am J Dis Child. 1970;120(1):26-31. doi:10.1001/archpedi.1970.02100060060007