The human immunodeficiency virus (HIV) is the virus that causes acquired immunodeficiency syndrome (AIDS), a chronic life-threatening condition. HIV damages the immune system, which makes the body susceptible to infections that it would normally be able to fight off, states Medline Plus. According to MayoClinic.com, 39.5 million people worldwide are infected with HIV. The focus of highly active antiretroviral therapy (HAART) is to reduce the amount of virus in the bloodstream to suppress symptoms.
Nucleoside Analogue Reverse Transcriptase Inhibitors (NRTIs)
NRTIs were among the first antiretroviral drugs created to fight off HIV, according to MayoClinic.com. This class of drugs, including zidovudine, lamivudine, didanosine, stavudine, abacavir and emtricitabine, inhibit the replication of reverse transcriptase, which is an enzyme that HIV uses to reproduce. Thus, inhibiting this chemical can prevent further replication of HIV and reduce the viral load in the bloodstream. Side effects include bone marrow suppression, rash, fever, stomach problems and skin discoloration.
Protease Inhibitors (PIs)
PIs also prevent the replication of the HIV virus. PIs interfere with HIV protease, which is an enzyme involved in HIV virus reproduction. Once HIV protease is inactivated, HIV particles in the body become noninfectious. Drugs in this class include saquinavir, ritonavir, indinavir, nelfinavir, amprenavir, darunavir and others. Side effects include stomach problems, liver damage, weight changes and altered sugar metabolism.
Fusion Inhibitors
A fusion inhibitor, such as Fuzeon, is a newer class of drugs developed to fight drug-resistant strains of HIV, states MayoClinic.com. If first-line HIV medications are ineffective, a doctor may prescribe a fusion inhibitor. This medication prevents the replication of the HIV virus because it prevents the HIV viral membrane from fusing with the patient's healthy cell membrane. A patient should let his doctor know if he is experiencing chest congestion, shortness of breath, flulike symptoms, nerve pain or weakness, according to Drugs.com.
Integrase Inhibitors
Integrase inhibitors are another class of drugs used to fight resistant HIV strains. Raltegravir, the only drug in this class, works by blocking the activity of the HIV integrase enzyme, which prevents HIV genes from inserting into human genes. This medication may cause stomach problems, headache or fever.
Chemokine Co-receptor Inhibitors (CCR5 Antagonists)
CCR5 antagonists are used in combination with other antiretroviral drugs when viral load is elevated. Maraviroc is the only drug in this class that works by preventing HIV from entering human white blood cells. This drug is used to treat a particular type of HIV infection called CCR5-tropic HIV and is more effective at reducing viral load than standard therapy in this group of patients, states MayoClinic.com. Side effects include liver and heart problems, cough, rash and stomach pain.
