Human Immunodeficiency Virus

HIV Background

HIV destroys the body’s ability to fight infections by attacking cells of the immune system. In 1981, the first cases of Acquired Immunodeficiency Syndrome, or AIDS, were documented, and in 1983, HIV was identified as the cause of AIDS. According to a 2005 report by UNAIDS and the WHO, over 40 million people worldwide are living with HIV, and at least 25 million people worldwide have died from AIDS since the epidemic began. In the United States, the CDC have reported that the HIV mortality rate has steadily declined since the mid-to-late 1990s, while the incidence of infection continues to rise. This decrease in mortality can be attributed, in part, to the increased availability of HIV therapeutics used in the long-term treatment of HIV. According to a 2005 UNAIDS/WHO report, by the end of 2004, approximately 1.2 million people in North America and 720,000 people in Western and Central Europe were living with HIV and an additional 40,000 new patients are diagnosed each year in the United States.

The FDA has approved 23 single agents and six fixed-dose combination therapies for the treatment of HIV. The single agents are classified as nucleoside reverse transcriptase inhibitors, or NRTIs, non-nucleoside reverse transcriptase inhibitors, or NNRTIs, protease inhibitors, or PIs, or entry inhibitors. Both NRTIs and NNRTIs target the reverse transcriptase enzyme, while PIs and entry inhibitors target other proteins. The standard treatment for HIV infection, as recommended by the U.S. Department of Health and Human Services, includes two NRTIs combined with a third drug from another class, either an NNRTI or a protease inhibitor, to form a triple combination therapy known as Highly Active Anti-Retroviral Therapy, or HAART.