In the United States, there are 1,106,400 people living with HIV infection, according to the Centers for Disease Control and Prevention. Twenty-one percent of that population is unaware of their condition. Finding the most effective treatment that will keep the viral load low and has the fewest side effects is the goal of HIV therapy. By initiating highly activated antirviral therapy, or HAART, viral load can be reduced, according to MayoClinic. HAART usually requires a minimum of three drugs that work to reduce drug resistance and dwindling CD4 counts, two common HIV symptoms.
NRTIs
Most people after the initial HIV infection go through an asymptomatic stage that can last up to10 years. But as the virus continues to multiply, the immune system starts to lose the battle. It is important to check CD4 counts regularly to check on how well the immune system is doing. Dwindling CD4 counts are a common symptom of later stage HIV infection and a sign to start medications to support the immune system.
Some of the first medications to be developed to suppress the HIV virus were NRTIs, or nucleoside reverse transcriptase inhibitors. These medications block the production of the HIV enzyme reverse transcriptase, thereby slowing the virus from replicating. Zidovudine, or AZT, was one of the very first drugs developed in this class of medications. Other medications in this class include lamivudine, didanosine, stavudine and abacavir. Emtricitabine, a new drug in this class works not only against the HIV virus but Hepatitis B as well, which is significant because many patients infected with HIV also have Hepatitis B. Bone marrow suppression, meaning a decrease in the number of red and white blood cells, and hypersensitivity reactions---such as rash, fatigue, nausea and vomiting---can occur as side effects when using NRTIs.
Protease Inhibitors
By using multiple drugs, the HIV virus is prevented from replicating at various stages of the life cycle of the cell. This helps reduce another common symptom of HIV infection: drug resistance. Protease inhibitors block the HIV virus from replicating by interrupting an enzyme critical in the life cycle of the virus. According to MayoClinic, using protease inhibitors disorganizes the life cycle of the HIV cell and stops replication, thereby rendering it noninfectious. Drugs such as saquinavir, ritonavir, indinavir, nelfinavir amprenavir, lopinavir, ritonavir, atazanavir and tipranavir are protease inhibitors. One of the more troubling side effects of these medications, however, includes excessive weight loss as well as nausea and vomiting.
Integrase Inhibitors
Raltegravir is the only drug in this class of medications. This medication is used to treat patients who show symptoms of HIV drug resistance. Raltegravir is used in combination with other HIV medications, and its mechanism of action is to block the integrase enzyme of the HIV virus. This enzyme is what allows HIV to insert its DNA into human DNA. According to MayoClinic, common side effects include nausea, diarrhea, headache and fever.
