Antiretroviral Agents Used in the Treatment of HIV Infections
Harris, Wilhelmina, Brown, Geraldine, ABNF Journal
Abstract: The human immunodeficiency virus (HIV) is a global problem in today's society. Presently, there is no cure for this devastating disease, but there are many treatment modalities from which to choose. The medications called antiretroviral agents must be carefully selected and customized for each person who is being treated for an HIV infection. Physicians and pharmacists must use extreme care when these drugs are ordered, because if they are used improperly, there will be an increase in resistance to the virus. In order to prevent resistance, people should be properly educated about these agents, how they should be taken, as well as the specific schedule to which they should comply. Education is the major factor in assisting with bringing this disease under control and reducing transmission. Antiretroviral agents recommended for HIV infection through the stages of reproduction, transmission, and treatment are discussed.
Key Words: HIV, Antiretroviral Agents, Transmission, Treatment
HIV is presently the only causative factor known to cause the acquired immunodeficiency syndrome (AIDS). Even before the full-blown status of AIDS is noted in an HIV-positive individual, the virus has already started to destroy the immune system. Studies have shown that the virus invades the body during the stages of no visible symptoms and resides in high concentrations in lymph nodes where it continues to increase (Mulvihill et al., 2001).
The stages of HIV reproduction begins when HIV enters a CD+ cell. HIV is a retrovirus, meaning that its genetic information is stored on a single-stranded RNA instead of the double-stranded DNA found in most organisms. To replicate, HIV uses an enzyme known as reverse transcriptase to convert its RNA into DNA. HIV enters the nucleus of the CD4+ cell and inserts itself into the cell's DNA. HIV DNA then instructs the cell to make many copies of the original virus. New virus particles are then assembled, leave the cell and are ready to infect other CD4+ cells (Bartlett, 1997).
There are three classes of antiretroviral agents: nonnucleoside reverse transcriptase inhibitors, nucleoside analogues and the protease inhibitors. The first effective class of antiretroviral drugs was the nucleoside analogues. They act by incorporating themselves into the DNA of the virus, thereby stopping the building process. The resulting DNA is incomplete and cannot create new virus. Some of these drugs are Retrovir (zidovudine - also known as ZDV or AZT), Videx (didanosine - also known as ddl), and Combivir (lamivudine/zidovudine) (Armstrong, Goldman, Lacy, & Lance, 1999).
Protease inhibitors work at the last stage of the virus reproduction cycle. They prevent HIV from being successfully assembled and released from the infected CD4+ cell. This group of drugs include: invirase (saquinavir mesylate), Crixivan (indinavir), and Fortovase (saquinavir).
The newest class of antiretroviral agents are the nonnucleoside reverse transcriptase inhibitors (NNRTIs) that stop HIV production by binding directly on to reverse transcritase and prevent the conversion of RNA to DNA. These drugs are called "non-nucleoside" inhibitors because even though they work at the same stage as nucleoside analogues, they act in a completely different way. Examples of these drugs are VIRAMUNE (nevirapine), Rescriptor (delaviraline mesylate) and SUSTIVA (efavirenz).
The HIV virus is a member of the Lentivirus family consisting of retroviruses. HIV is known to be transmitted through three major routes, i.e., sexual contact, parenteral inoculation and passage of the virus from infected mothers to their newborns (Barlett, 1997).
HIV carries its genetic information as RNA rather than DNA. The virus infects certain white blood cells of the body's immune system, namely the helper T-4 lymphocytes, and destroys their ability to fight infection. The virus replicates itself within the lymphocyte, killing it, and spreading to others ( Mulvihill et al. …