COMPARATIVE EFFICACY OF PHENOBARBITAL, FLUMECINOL, AND URSODEOXYCHOLIC ACID IN THE MANAGEMENT OF HYPERBILIRUBINEMIA...

Gilbert syndrome (GS) is a common inherited disorder of bilirubin metabolism characterized by unconjugated hyperbilirubinemia due to reduced UGT1A1 activity. Despite the availability of several pharmacological agents capable of modulating bilirubin levels, no controlled comparative studies have systematically evaluated their relative efficacy and tolerability in adult patients with GS. The aim of this study was to compare the efficacy and safety of phenobarbital, flumecinol, and ursodeoxycholic acid (UDCA) in reducing serum bilirubin levels in patients with Gilbert syndrome.

A prospective, randomized, open-label, parallel-group study was conducted. Sixty patients with confirmed GS and baseline total bilirubin ≥34 µmol/L were randomized 1:1:1 to receive phenobarbital 50 mg/day (Group A, n=20), flumecinol 200 mg/day (Group B, n=20), or UDCA 10 mg/kg/day (Group C, n=20) for 14 days. The primary endpoint was the change in total serum bilirubin (Δ total bilirubin) from baseline to Day 14. Secondary endpoints included changes in unconjugated bilirubin, proportion of patients achieving ≥30% bilirubin reduction, and tolerability parameters. Intergroup comparisons were performed using one-way ANOVA with post hoc Tukey's test.

All three groups demonstrated significant bilirubin reduction after 14 days. Phenobarbital produced the greatest decrease in total bilirubin (-26.9±7.4 µmol/L), followed by flumecinol (-20.7±6.9 µmol/L) and UDCA (-12.1±6.3 µmol/L; p<0.001, ANOVA). Post hoc analysis confirmed significant differences between all pairwise comparisons: phenobarbital vs. flumecinol (p=0.02), phenobarbital vs. UDCA (p<0.001), and flumecinol vs. UDCA (p=0.01). The proportion of patients achieving ≥30% bilirubin reduction was 85%, 65%, and 30% in Groups A, B, and C, respectively. Similar trends were observed for unconjugated bilirubin. Somnolence was reported in 30% of phenobarbital-treated patients compared with 10% for flumecinol and 5% for UDCA. No clinically significant hepatotoxicity was observed.

Phenobarbital demonstrated the highest efficacy in reducing unconjugated hyperbilirubinemia in patients with Gilbert syndrome but was associated with a higher incidence of somnolence. Flumecinol offers a clinically meaningful bilirubin-lowering effect with a more favorable tolerability profile and may serve as a rational alternative. UDCA showed limited efficacy as a primary strategy for bilirubin reduction in GS and appears more appropriate for patients with concomitant biliary pathology.