Antiretroviral Therapy (ART)

SAN ANSELMO, CA - NOVEMBER 23: Bottles of antiretroviral drug Truvada are displayed at Jack's Pharmacy on November 23, 2010 in San Anselmo, California. A study published by the New England Journal of Medicine showed that men who took the daily antiretroviral pill Truvada significantly reduced their risk of contracting HIV. (Photo Illustration by Justin Sullivan/Getty Images). Justin Sullivan/Getty Images News/Getty Images

Definition: Antiretroviral therapies are drugs designed to work against a class of pathogens known as retroviruses. The most well known retrovirus is HIV, and most discussion of antiretroviral therapies revolves around HIV treatment.

Antiretroviral therapies can target any one of a number of processes required for the replication of a retrovirus. There are six classes of antiretroviral medications used in HIV treatment:

  • Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)
  • Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
  • Protease inhibitors (PIs), which interfere with the modification of viral proteins that is required for the formation of new HIV virus particles
  • Fusion inhibitors
  • CCR5 antagonists
  • Integrase inhibitors, which prevent integration of the viral DNA into the DNA of the infected cell

One of the most common targets of antiretroviral therapy is the enzyme known as reverse transcriptase, which is responsible for transforming the retrovirus's RNA into DNA so that it can be incorporated into the infected cell's genome. Drugs that target this enzyme are known as reverse transcriptase inhibitors.

Reverse transcriptase inhibitors fall into two categories: nucleoside reverse transcriptase inhibitors (also called nucleotide reverse transcriptase inhibitors), or NRTIs, and non-nucleoside reverse transcriptase inhibitors, or NNRTIs.

NRTIs are "fake" versions of the elements that make up DNA. They are designed to be integrated into the copied viral genome to block further elongation. In contrast, NNRTIs affect the action of reverse transcriptase directly.

Also Known As: HAART, cART

Alternate Spellings: anti-retroviral

Examples: Tenofovir is a reverse transcriptase inhibitor that is used as an antiretroviral HIV treatment.

It is usually part of a combined antiretroviral therapy (cART) regimen.

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