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Health A-Z

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Harvard Medical School

Treatment

The International AIDS Society USA Panel recommends that patients start taking antiviral medications (antiretrovirals) before the CD4 count falls below 350 cells per cubic milliliter of blood. Many experts suggest using 500 as the benchmark. Most recently, some doctors are recommending starting treatment immediately after the diagnosis is confirmed. The exact timing will depend on many factors, risks and benefits that should be discussed by the patient and the doctor.

If the decision is made to start treatment, your doctor will choose a combination of drugs called antiretrovirals to fight your HIV infection. To control the reproduction of HIV in the body, several medications must be used together (often called a drug cocktail or highly active antiretroviral therapy (HAART). These medications attack HIV at multiple points in its growth cycle and are more effective in suppressing the virus. Combining drugs also limits the risk that HIV will become resistant to drugs, which would mean the drugs are powerless against this resistant strain of HIV.

Many studies have shown that people with high levels of virus in the blood (the viral load) will progress more rapidly to AIDS. Though it is not possible to clear the virus from the body completely, the goal of treatment is to keep the virus from reproducing. This can be seen when the viral load test cannot detected the HIV virus in the bloodstream (the virus never goes away, just goes to very low levels). When the virus is not reproducing quickly, it is less likely to kill CD4 cells. As the CD4 cell count increases, the immune system regains strength.

There are many available antiretroviral medications in the United States today. Many of these can be prescribed in combination form making the total number of different "pills" available closer to 30. Many medications have two or three names and may be referred to by the generic name, trade name or a three letter abbreviation (for example, AZT is also known by its generic name, zidovudine, and by its trade name, Retrovir). Currently available antiretroviral drugs include:

  • Nucleoside reverse transcriptase inhibitors (NRTIs), such as zidovudine (Retrovir, AZT), didanosine (Videx, ddI), stavudine (Zerit, d4T), abacavir (Ziagen, ABC), emtricitabine (Emtriva, FTC) and lamivudine (Epivir, 3TC) block HIV reproduction at the virus' "reverse transcriptase." Tenofovir (Viread) is a commonly prescribed drug in a related family (nucleotide reverse transcriptase inhibitors). There are many NRTI combination pills including lamivudine and zidovudine (called Combivir) and emtricitabine and tenofovir (called Truvada).

  • Non-nucleoside reverse transcriptase inhibitors (NNRTIs), such as nevirapine (Viramune) and efavirenz (Sustiva) act on the same HIV reverse transcriptase that the NRTIs block, but at a different location.

  • Protease inhibitors (PIs), such as atazanavir (Reyataz), darunavir (Prezista), fosamprenavir (Lexiva), indinavir (Crixivan), nelfinavir (Viracept), ritonavir (Norvir), saquinavir (Invirase), , , and Tipranavir (Aptivus) block the assembly of new HIV virus particles (they inhibit the virus' "protease"). The PIs are often "boosted" with ritonavir to increase their potency. Lopinavir and ritonavir are combined into one pill (Kaletra) for this purpose.

  • Cell entrance blockers. A fusion inhibitor called enfuvirtide (Fuzeon) and a CCR5 co-receptor antagonist called maraviroc (Selzentry) are currently the only medications available that block HIV from getting inside the cell in the first place. These medications block the virus at the cell surface. Enfuvirtide is only available in injectable form.

  • Integrase inhibitor. Raltegravir (Isentress) is the only medication available today that blocks the "integration" of the virus' genetic material with the cell's genetic material. This blocks HIV from reproducing inside the cell.

Numerous combinations can be made depending on patient and doctor preference. Because many of these drugs have side effects, such as nausea and diarrhea, the exact medications prescribed for a particular person may depend on side effects (which will be different from person to person).

A commonly recommend initial therapy is a combination of the NNRTI efavirenz (Sustiva) and two NRTIs. A potential choice for people who are likely to miss doses of medication is a combination pill called Atripla. It contains efavirenz, emtricitabine and tenofovir. Atripla is taken as one pill, once per day.

It is very important to tell your doctor about ALL other medications you take (including herbals and non-prescription medications) because there can be serious drug-drug interactions with commonly used medications. Also, no one should take an antiretroviral medication that was not specifically prescribed for them by a health care provider.

In addition to antiretrovirals, people with low CD4 counts should take drugs to prevent the development of opportunistic infections. For example, people with CD4 cell counts below 200 cells per milliliter of blood should take trimethoprim-sulfamethoxazole (known as Bactrim or Septra) to protect themselves against Pneumocystis pneumonia.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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