Human immunodeficiency virus, or HIV, is a type of retrovirus that replaces normal cellular DNA with its own viral genetic material, causing progressive damage to the body's immune system. HIV infection can eventually lead to the life-threatening condition known as AIDS, or acquired immune deficiency syndrome. There are many approved drugs available to treat people with HIV. These drugs work to suppress HIV replication in an attempt to slow the progression of disease.
Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
To multiply and incorporate its own viral DNA into the body's existing genetic code, HIV must first convert its RNA to DNA. This conversion is carried out by an enzyme called reverse transcriptase. Nucleoside reverse transcriptase inhibitors (NRTIs) are drugs that trick reverse transcriptase into using them as building blocks for conversion to DNA, only to block the conversion and prevent HIV from multiplying, according to eMedTV.
Approved nucleoside reverse transcriptase inhibitors include abacavir, the combination drug abacavir and lamivudine, the combination drug abacavir, lamivudine and zidovudine, didanosine, emtricitabine, the combination drug emtricitabine and tenofovir, lamivudine, stavudine, tenofovir, zidovudine and the combination drug lamivudine and zidovudine, according to AIDSinfo, an information service of the United States Department of Health and Human Services.
Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
Like NRTIs, non-nucleoside reverse transcriptase inhibitors (NNRTIs) also prevent HIV from multiplying; however, they do so by binding directly to reverse transcriptase and blocking its functioning, according to eMedTV. Approved NNRTIs include delavirdine, efavirenz, etravirine and nevirapine, according to AIDSinfo.
Tenofovir
Tenofovir is a nucleotide reverse transcriptase inhibitor, or NtRTI. According to eMedTV, it works in the same manner as the NTRIs and differs only in its chemical structure. Currently, tenofovir is the only approved NtRTI on the market.
Protease Inhibitors
The protease enzyme is used by the HIV virus to clip strands of DNA into shorter segments that are then used to make new viruses. Protease inhibitors are drugs that block that action of protease enzymes, thereby suppressing the spread of HIV to additional cells, according to eMedTV. Approved protease inhibitors include amprenavir, atazanavir, darunavir, fosamprenavir, indinavir, nelfinavir, saquinavir and tipranavir, according to AIDSinfo. Ritonavir is a special drug in this class that is used to boost the effectiveness of other protease inhibitors. It is often used in combination with other protease inhibitors such as a lopinavir and ritonavir combination.
Entry/Fusion Inhibitors
Entry/fusion inhibitors are drugs that block HIV's entry into human cells. The two entry/fusion inhibitors approved for the treatment of HIV and AIDS are enfuvirtide and maraviroc, according to AIDSinfo.
Integrase Inhibitors
According to AIDSinfo, integrase inhibitors are drugs that work by disabling a critical protein called integrase that is needed by the human immunodeficiency virus. HIV uses integrase to help it replace normal genetic material in a cell with its own viral DNA. By disabling integrase, these drugs may help to prevent or slow HIV progression. Currently, raltegravir is the only integrase inhibitor approved for the treatment of HIV.
Combination Drugs
Combination drugs are those that contain at least two different approved medications. In some cases, these drugs may be from different classes. According to eMedTV, using combination medications may prevent the body from becoming resistant to any single drug. It is not uncommon for doctors to prescribe three to five drugs at one time as part of an aggressive treatment regimen known as highly active antiretroviral therapy (HAART) that is meant to suppress HIV replication and progression. These drugs may be combined into a fixed-dose, single tablet or capsule to make them easier to take. Fixed-dose combination drugs include abacavir and lamivudine, abacavir, lamivudine and zidovudine, efavirenz, emtricitabine and tenofovir, emtricitabine and tenofovir, and lamivudine and zidovudine, according to AIDSinfo.
