Effect of Phenobarbital on Elevated Direct Bilirubin Concentrations in Neonates and Infants in the Neonatal Intensive Care Unit.

OBJECTIVE Few studies have evaluated the effect of phenobarbital (PB) on elevated direct bilirubin (DB) plasma concentrations in neonates and infants, and none have compared its effect with a control group with matched study baseline DB values. The purpose of this study was to quantify changes in elevated DB plasma concentrations (≥2 mg/dL) in neonates and infants between a PB-treated and control group. METHODS A retrospective, observational, matched, cohort study was performed comparing patients between a PB-treated group and a control group with similar study baseline plasma DB values ≥2 mg/dL over an 8-week period. The percent change in DB plasma concentrations from study baseline was compared for each week of the study period. RESULTS During the 8-year study period, 310 patients had DB plasma concentrations ≥2 mg/dL, of which 26 remained in each group after exclusions. The PB group had increased DB concentrations and the control group had decreased DB concentrations when compared with their study baseline DB concentrations each week of the study period. By study end, the mean DB concentration increased by 11.2% in the PB group and decreased by 48.5% in the control group (p = 0.02). In multiple regression analysis, only birth weight (standardized coefficient = 0.44, p = 0.02), and gastrointestinal obstruction (standardized coefficient = -0.4, p = 0.03) were associated with significant percent change in DB concentrations. CONCLUSIONS This study demonstrated PB does not improve cholestasis in neonates and infants.