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Entry Inhibitors for HIV


Generic NameBrand Name
enfuvirtideFuzeon, Selzentry
maravirocFuzeon, Selzentry

Enfuvirtide is available only as an injection. Maraviroc is also called a chemokine receptor 5 (CCR-5) inhibitor.

How It Works

When HIV invades your body, the virus attaches to the outside of a CD4+ cell (a type of white blood cell) where it joins (fuses) with the cell and then multiplies. Entry inhibitors prevent fusion between the virus and the cell from occurring and prevent the virus from entering the cell. So HIV is not able to infect the cell and multiply.

Why It Is Used

Enfuvirtide and maraviroc are used in combination with other antiretroviral medicines for the treatment of HIV to prevent the virus from spreading in the body and to reduce the amount of virus in your blood (viral load). Enfuvirtide and maraviroc may be effective for people who have taken other anti-HIV drugs without success.

The use of three or more antiretroviral medicines (antiretroviral therapy, or ART) is the usual treatment for HIV infection.

The combination of medicines used for ART will depend on your health, other conditions you might have (such as hepatitis), and results of testing. Talk to your doctor about the best treatment plan for you.

Medical experts recommend that people begin treatment for HIV as soon as they know they are infected.1, 2 Treatment is especially important for pregnant women, people who have other infections (such as tuberculosis or hepatitis), and people who have symptoms of AIDS.

You may also want to start HIV treatment if your sex partner does not have HIV. Treatment of your HIV infection can help prevent the spread of HIV to your sex partner.3

Click here to view a Decision Point.HIV: When Should I Start Antiretroviral Medicines for HIV Infection?
Click here to view an Actionset.HIV: Taking Antiretroviral Drugs

How Well It Works

Enfuvirtide and maraviroc strengthen the immune system by reducing the amount of virus in the blood and increasing CD4+ counts.4, 5

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Callor other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.

Call your doctor if you have:

  • Hives.

Common side effects of enfuvirtide include:

  • Skin itchiness.
  • Swelling and pain at the site of the injection.
  • Numbness in the feet or legs.
  • Dizziness.
  • Trouble sleeping.

Common side effects of maraviroc include:

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Maraviroc is only effective against certain strains of HIV. Before maraviroc treatment is considered, you need to be tested to see if maraviroc will work against the virus you are infected with. This is called a tropism test. You should not take maraviroc unless you have had this test and it shows that maraviroc will be effective against the type of virus you have.

Enfuvirtide and maraviroc are used in combination with other anti-HIV drugs.

HIV can become resistant to enfuvirtide, so your viral load and CD4+ cell counts will be closely monitored while you are taking this medicine.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)Click here to view a form.(What is a PDF document?) to help you understand this medication.



  1. U.S. Department of Health and Human Services Panel on Antiretroviral Guidelines for Adults and Adolescents (2012). Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents. Available online:

  2. Thompson MA, et al. (2012). Antiretroviral treatment of adult HIV infection: 2012 recommendations of the International Antiviral Society—USA Panel. JAMA, 308(4): 387–402.

  3. U.S. Department of Health and Human Services Panel on Antiretroviral Guidelines for Adults and Adolescents (2011). Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents. Available online:

  4. Lalezari JP, et al. (2003). Enfuvirtide, an HIV-1 fusion inhibitor, for drug-resistant HIV infection in North and South America. New England Journal of Medicine, 348(22): 2175–2185.

  5. Hanson K, Hicks C (2006). New antiretroviral drugs. Current HIV/AIDS Reports, 3(2): 93–101.


ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerPeter Shalit, MD, PhD - Internal Medicine
Last RevisedNovember 7, 2012

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