TY - JOUR T1 - Use of Phenotypically Poor Metabolizer Individual Donor Human Liver Microsomes to Identify Selective Substrates of UGT2B10 JF - Drug Metabolism and Disposition JO - Drug Metab Dispos DO - 10.1124/dmd.119.089482 SP - dmd.119.089482 AU - Nicolo Milani AU - Nahong Qiu AU - Birgit Molitor AU - Justine Badée AU - Gabriele Cruciani AU - Stephen Fowler Y1 - 2019/01/01 UR - http://dmd.aspetjournals.org/content/early/2019/12/15/dmd.119.089482.abstract N2 - UGT1A4 and UGT2B10 are the human UGT isoforms most frequently involved in N-glucuronidation of drugs. UGT2B10 exhibits higher affinity than UGT1A4 for numerous substrates making it potentially the more important enzyme for these compounds in vivo. Clinically relevant UGT2B10 polymorphisms, including a null activity splice site mutation common in African populations, can lead to large exposure differences for UGT2B10 substrates that may limit their developability as marketed drugs. UGT phenotyping approaches using recombinantly expressed UGTs are limited by low enzyme activity and lack of validation of scaling to in vivo. In this study we describe the use of an efficient experimental protocol for UGT2B10 selective substrate identification, which exploits the activity difference between pooled HLM and HLM from a phenotypically UGT2B10 poor metabolizer donor. Following characterization of the approach with eight known UGT2B10 substrates, we used ligand-based virtual screening and literature precedents to select 24 potential UGT2B10 substrates out of 140 UGT-metabolized drugs for testing. Of these, dothiepin, cidoxepin, cyclobenzaprine, azatadine, cyproheptadine, bifonazole, and asenapine were indicated to be selective UGT2B10 substrates which have not previously been described. UGT phenotyping experiments and tests comparing conjugative and oxidative clearance were then used to confirm these findings. These approaches provide rapid and sensitive ways to evaluate whether a potential drug candidate cleared via glucuronidation will be sensitive to UGT2B10 polymorphisms in vivo.SIGNIFICANCE STATEMENT The role of highly polymorphic UGT2B10 is likely to be underestimated currently for many compounds cleared via N-glucuronidation due to high test concentrations often used in vitro and low activity of UGT2B10 preparations. The methodology described in this study can be combined with the assessment of UGT vs oxidative in vitro metabolism to rapidly identify compounds likely to be sensitive to UGT2B10 polymorphism, enabling either chemical modification or prospective exposure polymorphism risk assessment to be performed before candidate selection. ER -