Antiretroviral therapy utilizes a combination of drugs, typically three, to fight the human immunodeficiency virus (HIV) that causes acquired immunodeficiency syndrome (AIDS), the name given to late-stage HIV. The World Health Organization continues to make progress in upgrading the potency and effectiveness of antiretroviral drugs for the more than 33 million people in the world living with the fatal virus.
NRTIs
Nucleoside analogue reverse transcriptase inhibitors (NRTIs) are drugs that prevent the replication of the HIV enzyme. Brand names of NRTIs include Retrovir, Epivir and Emtriva, with the latter being the newest NRTI drug that also is used to treat hepatitis B. Each of the drugs carries various side effects that range from skin discoloration to fatigue, nausea and diarrhea. Bone marrow suppression and abdominal pain also are common side effects. Symptoms of adverse reactions typically appear within the first six weeks of taking the drugs.
PIs
Protease inhibitors (PIs) work on HIV in its later stages to inhibit growth of the virus. The HIV protease is interrupted and causes the virus particles to disperse and become noninfectious. Some brand name PIs include Novir, Viracept and Aptivus. Common side effects of PIs are diarrhea, nausea and digestive tract disorders. They also can cause increased triglyceride levels and interfere with sugar metabolism, leading to diabetes. PIs also can interfere with fat metabolism and cause some patients to lose weight, while others gain weight in certain areas.
Fusion Inhibitors
Doctors at the Mayo Clinic report that many patients develop a resistance to antiretroviral therapies, making them ineffective in treating HIV/AIDS. However, fusion inhibitors were created to suppress those resistant strains. The drug known as Fuzeon fuses with the membranes of healthy cells in the body to prevent the spread of HIV. Fuzeon typically is administered by injection to patients with advanced HIV who have developed resistances to their antiretroviral therapies. While fusion inhibitors have fewer side effects, they can cause reactions at the site of the injection and lead to more frequent bouts of pneumonia.
CCR5 Antagonists
Chemokine co-receptor inhibitors, also called CCR5 antagonists, attack human protein rather than the HIV components. Selzentry is the only drug in this class and is used to treat adults with CCR5-tropic HIV-1, a specific type of HIV virus. Patients who develop elevated levels of HIV despite other treatments are given CCR5 antagonists to prevent the virus from infecting healthy white blood cells. Side effects can include upper respiratory tract infections, rash, fever, cough and abdominal pain.
