Droxinavir is hydroxyethylurea human immunodeficiency virus type 1 (HIV-1) protease inhibitor. Position 88 of HIV-1 protease gene plays a key role in the interaction between droxinavir and the protease molecule. A mutation in this position, located outside the active site, confers resistance to the hydroxyethylurea inhibitor droxinavir. The V82A and N88S substitutions conferred droxinavir resistance on HIV-1 recombinant variants. Positions 82 and 88 are reported to be variable in natural populations isolated from patients who have not been treated with protease inhibitors. Droxinavir had been in preclinical phase for the treatment of HIV-1 infection. However, this study was discontinued.