Antiretroviral drugs
Antiretroviral drugs prevent the reproduction of a type of virus called a retrovirus. The human immunodefiency virus (HIV), that causes acquired immune deficiency syndrome (AIDS), is a retrovirus. These drugs are therefore used totreat HIV infections. These medicines cannot prevent or cure HIV infection, but they help to keep the virus in check.
Viruses are tiny, disease-causing particles that are unable to reproduce on their own. They must invade the cells of other living things and take over thecells' machinery in order to multiply. In the process, they cause illness. HIV is a specific type of virus called a retrovirus. It slowly weakens the immune system by invading and destroying special immune cells that help defend the body against infections.
Antiretroviral drugs do not kill viruses, because that could also damage or kill the cells the viruses have infected. Instead, these drugs block the reproduction of the viruses. However, they do not eliminate HIV and restore the immune system completely. Hence, people who take these drugs may still get serious infections and have other health problems. Furthermore, antiretroviral drugs do not prevent the spread of HIV from an infected person to someone else.People taking these drugs must still observe all precautions to avoid infecting others.
- There are three main types of antiretroviral drugs:
- Nucleoside analogs, or nucleoside reverse transcriptase inhibitors (NRTIs), such as didanosine(ddI, Videx), lamivudine (3TC, Epivir), stavudine (d4T, Zerit), zalcitabine (ddC, Hivid), and zidovudine (AZT, Retrovir).
- Non-nucleoside reversetranscriptase inhibitors (NNRTIs), such as delavirdine (Rescriptor), loviride, and nevirapine (Viramune)
- Protease inhibitors, such as indinavir (Crixivan), nelfinavir (Viracept), ritonavir (Norvir) and saquinavir (Invirase).
Many of these drugs became available only in the mid- to late-1990s, and their introduction changed the way physicians treat HIV. Instead of being limitedto just a few drugs, physicians now carefully choose combinations of these drugs for patients to take together. In the past, antiretroviral drugs were prescribed only when patients became very ill. But increasingly, they are beinggiven earlier to keep people infected with HIV from getting so sick.
These medicines are available only with a physician's prescription and come in liquid, tablet, capsule, and injectable forms. Physicians consider many factors when deciding the correct dosage for each patient, such as body weight and overall general health. Patients using this medicine must carefully followall instructions, making sure to take the medicine at the proper time and toschedule meals as directed. Always take antiretroviral drugs exactly as directed. Never take larger or more frequent doses, and do not take the drug forlonger than directed. Take only the medicine that has been prescribed, and donot share this medicine with anyone else. Because these drugs can cause serious side effects, patients must pay close attention to their health and mustmake regular visits to their physicians. Anyone considering taking antiviraldrugs should be sure to understand all the risks, benefits and requirements of this treatment.
Do not stop taking this medicine without checking with the physician who prescribed it. The only exception is for patients who have severe nausea, vomiting, and stomach pain. These symptoms could be signs of inflammation of the pancreas. Patients who have these symptoms should stop taking the medicine and call their physicians immediately. In all other cases, it is very important tokeep taking the drugs, even if symptoms improve.
People with certain medical conditions or who are taking certain other medicines may have problems if they take antiretroviral drugs. Before using antiretroviral drugs, people should make sure their physicians are aware of all their medical conditions. Anyone who has had unusual reactions to antiretroviraldrugs in the past should let his or her physician know before taking the drugs again. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances. Women infected with HIV, who are eitherpregnant or are breast feeding their infants, should discuss the use of these drugs with their physicians.
Taking antiretroviral drugs with certain other drugs may affect the way the drugs work or may increase the chance of side effects. Some side effects occurearly in treatment, but usually go away as the body adjusts to the drug. Among these are anxiety, irritability, restlessness, diarrhea, headache, sore muscles, dry mouth, and sleep problems. These side effects do not require medical treatment unless they continue or are troublesome. More serious side effects may also occur. If any unusual symptoms occur, check with a physician immediately. Anyone who develops new or unusual symptoms while taking antiretroviral drugs should get in touch with his or her physician. Be sure to checkwith a physician before taking any other prescription or nonprescription (over-the-counter) medicine.