The human immunodeficiency virus infection cripples the immune system of the body, leading to the development of acquired immunodeficiency syndrome. Estimates from the Centers for Disease Control and Prevention put the number of people living with HIV/AIDS in the United Staes at more than 1 million, with more than 50,000 new cases each year.
Drugs, according to AIDS.gov, are used to reduce the amount of virus in the body and protect the immune system. As of April 2010, there were five classes of drugs used in HIV/AIDS treatment, called antiretroviral drugs. A cocktail of at least three drugs is usually prescribed.
Nucleoside/Nucleotide Reverse Transcriptase Inhibitors
These interfere with the enzyme involved in the replication of viral genetic material. According to AIDS.gov, they provide faulty building blocks that foul up the process of producing new viral genes. They include zidovudine (AZT), lamivudine (3TC), abacavir (ABC), didanosine (ddI), emtricitabine (FTC), stavudine (d4T) and tenofovir disoproxil fumarate (TDF).
Combination pills of drugs in this class are available. They include Combivir (3TC and AZT), Epzicom (3TC and ABC), Trizivir (AZT, 3TC and ABC) and Truvada (TDF and FTC).
Non-Nucleoside Reverse Transcriptase Inhibitors
These drugs act directly on the enzyme reverse transcriptase without providing faulty building blocks. They also block the production of viral genes.
They include delavirdine (DLV), efavirenz (EFV), etravirine (ETR) and nevirapine (NVP). Atripla is a combination of efavirenz, a non-nucleoside reverse transcriptase inhibitor with two nucleoside reverse transcriptase inhibitors (EFV with FTC and TDF).
Protease Inhibitors
These drugs target the final stages in the production of new HIV genetic material by blocking the enzyme protease, which helps in chopping up the produced genes into viable bits. They include atazanavir (ATV), darunavir (DRV), amprenavir, fosamprenavir (FPV), indinavir (IDV), ritonavir (RTV), lopinavir (LPV), nelfinavir (NFV), saquinavir (SQV) and tipranavir (TPV).
Integrase Inhibitors
HIV requires its genetic material to be integrated into host genetic material before it can be multiplied. The drugs in this class block the enzyme that brings about this integration. The FDA-approved drug in this category is raltegravir (RAL). Other drugs in this class are still under investigation.
Fusion and Entry Inhibitors
These drugs block receptors on the host cell surfaces that enable HIV to fuse with the cell before gaining entry into the cell. Drugs in this group are enfuvirtide and maraviroc.
Highly Active Antiretroviral Therapy (HAART)
The national institutes of allergies and infectious diseases (NIAID) recommend a combination of drugs from at least two classes for effective antiretroviral therapy. This is called highly active antiretroviral therapy, or HAART. One such combination formulated into a fixed dose tablet form is Atripla, made up of EFV (non-nucleotide reverse transcriptase inhibitor) and two nucleotide reverse transcriptase inhibitors (FTC and TDF).
