The HIV virus that causes AIDS is a retrovirus, an RNA virus that uses the cell's machinery to transcribe itself into DNA and integrate itself into the genetic material of the cell before creating more RNA viral particles to send out and infect other cells. This type of virus is extremely difficult to fight, since it hides in the body's own cells. There are seven types of antiretroviral drugs designed to fight HIV, affecting the virus at different life stages. Most treatment strategies for AIDS involve combining three or more different anti-retroviral drugs to target various stages of HIV replication.
Nucleoside Reverse Transcriptase Inhibitors
Nucleoside reverse transcriptase inhibitors, also known as NRTIs, interfere with HIV's transcription of RNA into DNA by providing DNA building blocks that don't work properly. When the viral DNA is formed using these blocks, it doesn't work and the cycle of viral replication is halted. NRTIs include the drugs zidovudine under the brand name Retrovir and didanosine, which is marketed as Videx.
Nucleotide Reverse Transcriptase Inhibitors
Nucleotide reverse transcriptase inhibitors, referred to as NtRTIs, also provide faulty DNA components that are then incorporated into the DNA copy of HIV, rendering it inert. The nucleotide reverse transcriptase inhibitor tenofovir is sold under the brand name Viread.
Non-Nucleoside Reverse Transcriptase Inhibitors
Non-nucleoside reverse transcriptase inhibitors, also called NNRTIs, also work against the RNA-to-DNA transition, but these function by binding to reverse transcriptase, the molecule that normally carries out the conversion of RNA to DNA. With its reverse transcriptase bound up, the virus can't complete the conversion process. Some non-nucleoside reverse transcriptase inhibitors on the market are etravirine, which goes by the brand name Intelence, and nevirapine, which is sold as Viramune.
Protease Inhibitors
Protease inhibitors, or PIs, block the enzyme protease in HIV. This enzyme normally controls the production of viral particles, so protease inhibitors prevent HIV from creating new viruses. There are many protease inhibitors being manufactured, including ritonavir, atazanavir, tipranavir and darunavir, which respectively go by the brand names Norvir, Reyataz, Aptivus and Prezista.
Fusion Inhibitors
Fusion inhibitors block the virus from entering human cells by changing the viral membrane to prevent the virus from fusing to the membrane of the human host cell. The drug enfuvirtide goes by the brand name Fuzeon.
Integrase Inhibitors
Integrase inhibitors block the action of another HIV enzyme, this one called integrase. Integrase normally works to place HIV DNA into the human genetic code, where it can hide from detection and carry out the production of RNA viral particles. The integrase inhibitor raltegravir, brand name Isentress, is designed to be used in conjunction with other types of anti-retrovirals.
Chemokine Co-receptor Inhibitors
This type of AIDS medication blocks a protein receptor on the surface of human immune cells, which prevents HIV from binding to those receptors and entering the cell. Maraviroc goes by the brand name Selzentry.
