(rel)-Lopinavir-d8 ((rel)-ABT-378-d8) is the deuterium labeled Lopinavir (HY-14588)[1]. Lopinavir (ABT-378) is a highly potent, selective peptidomimetic inhibitor of the HIV-1 protease, with Kis of 1.3 to 3.6 pM for wild-type and mutant HIV protease. Lopinavir acts by arresting maturation of HIV-1 thereby blocking its infectivity[2][3]. Lopinavir is also a SARS-CoV 3CLpro inhibitor with an IC50 of 14.2 µM[4].