Human immune deficiency virus (HIV), the virus that causes acquired immune deficiency syndrome (AIDS) continues to pose a challenge for treatment. According to the National Institute of Allergy and Infectious Diseases (NIAD), there are more than 1 million people living with the disease in the U.S. and more than 37 million worldwide. HIV remains incurable to date with several drugs being used to control the progress and spread of the disease as well as episodes of opportunistic infections.
Reverse Transcriptase Inhibitors
These agents interfere with the replication of the HIV by blocking the development of a template vital to the manufacture of viral genes. There are two classes in this group of drugs.The nucleoside/nucleotide reverse transcriptase inhibitors work by providing faulty building blocks for the viral replication process. This eventually cripples the process. Drugs in this class include abacavir (Ziagen) didanosine (Videx EC), emtricitabine (Emtriva), lamivudine (Epivir) stavudine (Zerit), tenofovir DF (Viread) and zidovudine (Retrovir). Combinations in this class include Combivir (lamivudine and zidovudine), Epzicom (lamivudine and abacavir), Truvada (tenofovir DF and emtricitabine) and Trizivir (lamivudine, zidovudine and abacavir).
Non-nucleoside reverse transcriptase inhibitors work by directly attaching themselves to the enzyme involved in translating the viral genes and neutralizing the enzyme. Drugs in this class include delavirdine (Rescriptor), efavirenz (Sustiva), etravirine (Intelence) and nevirapine (Viramune).
Protease Inhibitors
Drugs in this group interfere with viral replication by blocking the process of producing infective viral units. Examples include atazanavir (Reyataz), darunavir (Prezista), amprenavir (Agenerase), fosamprenavir (Lexiva), indinavir (Crixivan), nelfinavir (Viracept), ritonavir (Novir), saquinavir (Invirase), and tipranavir (Aptivus). A combination formulation, Kaletra (lopinavir and ritonavir) is also available.
Fusion/Entry inhibitors
Drugs in this group block the virus from attaching itself to the host cell, thus blocking entry and infection of the host cell. Examples are enfuvirtide (Fuzeon) and maraviroc (Selzentry).
Integrase Inhibitors
These block the integration of HIV genetic material into host cell genes. The one approved drug in this category is raltegravir (Isentress).
Multi-drug Combinations
According to the NIAD, due to the ease of development of drug resistance in HIV, health providers have to use a combination of drugs to treat the infection. A combination of up to three drugs from at least two of the groups previously mentioned is called highly active anti-retroviral therapy, or HAART. One such multi-drug tablet is Atripla (efavirenz, emtricitabine and tenofovir DF). Combinations of drugs could also be taken in a mixture of tablets called a "cocktail."
References
- National Institutes of Allergy and Infectious Diseases: HIV/AIDS quick facts
- National Institutes of Allergy and Infectious Diseases: HIV/AIDS Antiretroviral Drug Classes
- National Institutes of Health/AIDSInfo: Adult and Adolescent Treatment Guidelines (Appendix B)
- U.S Department of Health and Human Services/AIDS.gov: Overview of HIV Treatments
