As quickly as HIV appears to develop resistance to various classes of highly active antiretroviral therapy (HAART), companies are developing new therapeutic classes to combat the disease. While combination therapy will continue to be standard practice to prevent viral replication, newer classes of therapeutics may end up replacing accepted approaches in HAART regimens.

In particular, the use of HIV protease inhibitors (PIs) may begin to wane. The PI class includes Viracept nelfinavir from Agouron Pharmaceuticals Inc. (La Jolla, Calif.), Crixivan indinavir from Merck & Co. Inc. (Whitehouse Station, N.J.), Norvir ritonavir from Abbott Laboratories (Abbott Park, Ill.), Invirase saquinavir from Hoffmann-La Roche Inc. (Nutley, N.J.) and Agenerase amprenavir from Vertex Pharmaceuticals Inc. (VRTX, Cambridge, Mass.).