Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV. When several of such drugs, typically three or four, are taken in combination, the approach is known as Highly Active Antiretroviral Therapy, or HAART.
Antiretroviral drugs inhibit the reproduction of retroviruses—viruses composed of RNA rather than DNA. The best known of this group is HIV, human immunodeficiency virus, the causative agent of AIDS. 1
Antiretroviral agents are virustatic agents which block steps in the replication of the virus. The drugs are not curative; however continued use of drugs, particularly in multi-drug regimens, significantly slows disease progression.1
There are three main types of antiretroviral drugs, although only two steps in the viral replication process are blocked. Nucleoside analogues, or nucleoside reverse transcriptase inhibitors (NRTIs), such as didanosine, lamivudine, stavudine, zalcitabine, and zidovudine, act by inhibiting the enzyme reverse transcriptase. Because a retrovirus is composed of RNA, the virus must make a DNA strand in order to replicate itself. Reverse transcriptase is an enzyme that is essential to making the DNA copy. The nucleoside reverse transcriptase inhibitors are incorporated into the DNA strand. This is a faulty DNA molecule that is incapable of reproducing.
The non-nucleoside reverse transcriptase inhibitors (NNRTIs), such as delavirdine, loviride, and nevirapine act by binding directly to the reverse transcriptase molecule, inhibiting its activity.
Because HIV mutates readily, the virus can develop resistance to single drug therapy. However, treatment with drug combinations appears to produce a durable response. Proper treatment appears to slow the progression of HIV infections and reduce the frequency of opportunistic infections. One of the most notable advances in recent years has been the success of highly active antiretroviral therapy (HAART). This multidrug approach reduced the risk of opportunistic infections in persons with HIV/AIDS and slowed the progression of the disease and death.1
- http://medical-dictionary.thefreedictionary.com/Antiretroviral+Drugs (2 May 2019)