Nelfinavir Mesylate is a potent inhibitor of HIV-1 protease [1].HIV-1 protease is a constitutive enzyme that processes gag and gag-pol polyproteins for packaging into the nascent virion actively budding from a productively infected cell. Inhibition of the enzyme results in the formation of immature non-infectious particles [2].Nelfinavir Mesylate is a potent inhibitor of HIV-1 protease with Ki of 2.0 nM. In CEM cells infected with the HIV strain IIIB, Nelfinavir Mesylate was potent antiviral agent with ED50 value of 14 nM and exhibited minimal cellular toxicity (TD50s > 5000 nM) [1]. In CEM-SS and MT-2 cells, Nelfinavir Mesylate protected these cells from acute HIV-1 RF- and HIV-1 IIIB-induced cell killing with EC50s ranging from 31 to 43 nM [3].In 65 HIV-1-infected patients, Nelfinavir Mesylate was well-tolerated and exhibited robust antiviral activity with demonstrable superiority of the 750 mg and 1000 mg three times daily regimens. Thirty patients who continued to receive therapy at 12 months acquired a persistent 1.6 log10 reduction in HIV RNA, accompanied by a mean increase in CD4 cells of 180-200/mm3 [2].References:[1]. Kaldor SW, Kalish VJ, Davies JF, et al. Viracept (nelfinavir mesylate, AG1343): a potent, orally bioavailable inhibitor of HIV-1 protease. J Med Chem, 1997, 40(24): 3979-3985.[2]. Markowitz M, Conant M, Hurley A, et al. A preliminary evaluation of nelfinavir mesylate, an inhibitor of human immunodeficiency virus (HIV)-1 protease, to treat HIV infection. J Infect Dis, 1998, 177(6): 1533-1540.[3]. Patick AK, Mo H, Markowitz M, et al. Antiviral and resistance studies of AG1343, an orally bioavailable inhibitor of human immunodeficiency virus protease. Antimicrob Agents Chemother, 1996, 40(2): 292-297.