Nelfinavir is a potent hiv protease inhibitor. It is used in combination with other antiviral drugs in the treatment of hiv in both adults and children. Nelfinavir is a protease inhibitor. The mechanism of action of nelfinavir is as a hiv protease inhibitor. Nelfinavir is a synthetic antiviral agent that selectively binds to and inhibits human immunodeficiency virus (hiv) protease. Nelfinavir has activity against hiv 1 and 2. Nelfinavir mesylate is an inhibitor of hsp90.