Acquired immune deficiency syndrome, commonly known as AIDS, is a life-threatening disease in which the immune system slowly breaks down over time. AIDS is caused by the human immunodeficiency virus, or HIV. As of 2008, approximately 33.4 million people around the world were living with HIV or AIDS, according to MedlinePlus. When the disease first emerged in the 1980s, it frequently caused death within a few years. Since that time, many different medications, known as anti-retroviral drugs, have been developed that can suppress the progression of disease and significantly prolong life. However, there still is no cure for HIV or AIDS as of 2010.
Nucleoside Analogue Reverse Transcriptase Inhibitors
Nucleoside analogue reverse transcriptase inhibitors, also called NRTIs, are some of the earliest drugs developed to treat AIDS. NRTIs slow the growth of the HIV virus by blocking the virus from making an enzyme called reverse transcriptase, which the virus needs to replicate itself. Without the enzyme, the virus cannot grow as quickly, which can give the immune system a chance to replenish itself and fight off other infections. Currently available NRTIs include zidovudine, brand name Retrovir; lamivudine, brand name Epivir; didanosine, brand name Videx; stavudine, brand name Zerit; abacavir, brand name Ziagen; and emtricitabine, brand name Emtriva.
Protease Inhibitors
Another type of anti-retroviral drugs are protease inhibitors, or PIs. These drugs disrupt a later point of the HIV life cycle by inhibiting an enzyme called HIV protease. Without HIV protease, the virus forms into disorganized particles and cannot infect other cells, again giving the immune system a chance replenish itself. PIs are often prescribed with other anti-retroviral medications, such as the NRTIs, to form highly active anti-retroviral therapy, known as HAART. Currently prescribed PIs include saquinavir, brand name Invirase; ritonavir, brand name Norvir; indinavir, brand name Crixivan; nelfinavir, brand name Viracept; amprenavir, brand name Agenerase; lopinavir/ritonavir, brand name Kaletra; atazanavir, brand name Reyataz; tipranavir, brand name Aptivus; and darunavir, brand name Prezista.
Non-nucleoside Reverse Transcriptase Inhibitors
Non-nucleoside reverse transcriptase inhibitors, called NNRTIs, affect the same HIV enzyme as the NRTIs. However, instead of blocking the virus from making reverse transcriptase, NNRTIs bind to the enzyme after it has been made, and prevent it from functioning. NNRTIs are also often included in mixtures of HAART treatments. Currently available NNRTIs include nevirapine, brand name Viramune; delavirdine, brand name Rescriptor; efavirenz, brand name Sustiva; and etravirine, brand name Intelence.
Nucleotide Reverse Transcriptase Iinhibitors
Nucleotide reverse transcriptase inhibitors are known as NtRTIs. These drugs act very similar to NRTIs by preventing the HIV virus from making reverse transcriptase. However, NtRTIs work more quickly than NRTIs, and also slow the growth of the hepatitis B virus. NtRTIs are often given to patients after the HIV virus has become resistant to NRTIs. Only one NtRTI is currently approved for treatment, tenofovir, brand name Viread, according to the Mayo Clinic.
Fusion Inhibitors
Fusion inhibitors are a new type of drug that slow the growth of the HIV virus by preventing it from fusing to the human cells of the immune system. These drugs are often used only after HIV has become resistant to NRTIs, NNRTIs and NtRTIs. Enfuvirtide, brand name Fuzeon, is the only fusion inhibitor currently available.
Integrase Inhibitors
Integrase inhibitors target a different step of the HIV life cycle by preventing the virus from making an enzyme called HIV integrase that the virus needs to insert its DNA into the DNA of human cells it is infecting. Integrase inhibitors are almost always given in combination with other drugs. Only one integrase inhibitor, raltegravir, brand name Isentress, is currently available.
