Cobicistat-d8 is intended for use as an internal standard for the quantification of cobicistat by GC- or LC-MS. Cobicistat is an inhibitor of the cytochrome P450 (CYP) isomer CYP3A (IC50s = 30-285 nM for CYP3A metabolism of various HIV protease inhibitors).1 It is selective for CYP3A over other CYP isomers (IC50 = >25 μM for CYP1A2, 2C8, 2C9, and 2C19). Cobicistat does not inhibit HIV-1 protease (IC50 = >30 μM) or affect HIV replication in MT-2 cells (EC50 = >30 μM). Formulations containing cobicistat have been used to slow the metabolism of concomitantly administered protease inhibitors in the treatment of HIV.2
1.Xu, L., Liu, H., Murray, B.P., et al.Cobicistat (GS-9350): A potent and selective inhibitor of human CYP3A as a novel pharmacoenhancerACS Med. Chem. Lett.1(5)209-213(2010) 2.Harris, M., Ganase, B., Watson, B., et al.HIV treatment simplification to elvitegravir/cobicistat/emtricitabine/tenofovir disproxil fumarate (E/C/F/TDF) plus darunavir: A pharmacokinetic studyAIDS Res. Ther.14(1)59(2017)