UGT1A1 and Hyperbilirubinemia: Similarly, the inhibition of UGT1A1 by pazopanib or nilotinib has been reported to exacerbate hyperbilirubinemia in patients harboring UGT1A1 genetic polymorphisms (Figure 1B) [20,23,24,25,26,27,28,29,30,31,32,33].