Abacavir-d4 is intended for use as an internal standard for the quantification of abacavir by GC- or LC-MS. Abacavir is a nucleoside analog and an inhibitor of HIV-1 reverse transcriptase (Ki = 2.1 μM for the wild-type enzyme). It inhibits replication of a variety of HIV-1 and HIV-2 strains, including strains resistant to 3''-azido-3''-deoxythymidine (zidovudine; ) or 2'',3''-dideoxyinosine (didanosine; ), in HeLa cells stably expressing CD4 (IC50s = 5.8-21 μM). Abacavir inhibits replication of eight HIV-1 clinical isolates in phytohemagglutinin-stimulated isolated human peripheral blood lymphocytes with a mean IC50 value of 0.26 μM. It inhibits hepatitis B virus (HBV) DNA synthesis in HepG2 cells (IC50 = 7 μM) and is also active against human cytomegalovirus (CMV) strain AD169 and the Petaluma strain of feline immunodeficiency virus (FIV) in plaque reduction assays (IC50s = 32 and 0.4 μM, respectively). Formulations containing abacavir have been used in the treatment of HIV infection.
