Nonnucleoside reverse transcriptase inhibitors (NNRTIs) for HIV

Examples

Generic Name	Brand Name
delavirdine	Rescriptor
efavirenz	Sustiva
nevirapine	Viramune

How It Works

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are antiretroviral medicines. They prevent the human immunodeficiency virus (HIV) from multiplying. When the amount of virus in the blood is kept at a minimum, the immune system has a chance to recover and grow stronger.

Why It Is Used

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

The preferred combination is two nucleoside reverse transcriptase inhibitors with one protease inhibitor (PI) or efavirenz (a nonnucleoside reverse transcriptase inhibitor, or NNRTI). Two PI combinations are also used.

Treatment guidelines suggest the following for people with HIV:¹

• Experts currently consider your CD4+ count and presence or absence of symptoms much more important than your viral load, when considering treatment.
• If your CD4+ count is between 200 and 350 cells per microliter (mcL), you should be discussing treatment with your doctor to avoid letting your CD4+ cell count drop below 200.
• If your CD4+ count is more than 350 cells per microliter, treatment may be offered if you have mild (non-AIDS) symptoms of HIV infection, such as weight loss, fevers, or frequent yeast infections.
• If treatment is not started, your condition will be monitored with frequent CD4+ cell counts.
• If you have symptoms of HIV or AIDS, you should consider starting treatment, whatever your CD4+ count is.

Should I start antiretroviral medicines for HIV infection even though I have no symptoms?

Taking antiretroviral medicines for HIV infection

After HIV has progressed to AIDS, treatment is recommended.¹

How Well It Works

When compared with people who are given single- or double-medicine therapy, people who are given triple-medicine therapy (HAART):¹

• Have a greater reduction in viral load.
• Have better immune system recovery (measured by increased CD4+ cell counts).
• Are less likely to develop resistance to their medicines.
• Are likely to live longer.

Antiretroviral therapy can also decrease symptoms of HIV infection, such as fever, weakness, and weight loss.

The rate at which antiretrovirals decrease viral loads is affected by:¹

• CD4+ cell counts at the beginning of treatment.
• Viral load at the beginning of treatment.
• The dosage of the medicines.
• Whether medicines are taken exactly as prescribed.
• Whether antiretroviral medicines have been taken before.
• Whether opportunistic infections are present.

Side Effects

Side effects of nevirapine may include:

• Headache.
• Liver problems, which can be severe and life-threatening. Regular blood tests may be needed to monitor for liver problems.
• Nausea.
• Rash, which can be severe.

Side effects of delavirdine mesylate may include:

• Dizziness.
• Fatigue.
• Headache.
• Nausea, vomiting, and diarrhea.
• Rash.

Side effects of efavirenz may include:

• Difficulty sleeping (insomnia).
• Dizziness.
• Drowsiness (sedation).
• Vivid dreams.

Side effects usually are not as bad after your body has adjusted to the medicine. Report all side effects to your health professional. He or she may be able to help you reduce side effects by giving you other medicines.

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

What To Think About

Resistance to single-medicine NNRTI treatment develops quickly. For this reason, they should be used only in combination with other antiretroviral medicines to treat HIV infection or to prevent or delay the development of resistance.

Efavirenz can be taken once a day, in the evening on an empty stomach.

Efavirenz should not be taken at the same time as voriconazole (Vfend), a medicine that is used to treat serious fungal infections. Talk to your doctor about all medicines you are taking before starting a new medicine.

Factors to consider when choosing a combination of medicines include:

• The ability of the medicines to reduce your viral load.
• The likelihood that you will develop resistance to the medicines. If you have already been treated with a certain antiretroviral medicine, you may already know whether you are resistant to medicines in that class.
• Side effects and your willingness to tolerate them.
• The cost of treatment.

Many people think that antiretroviral medicines always have severe side effects. In fact, only a few people experience severe side effects.

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Author:	Maria G. Essig, MS, ELS	Last Updated: June 6, 2007
Medical Review:	Adam Husney, MD - Family Medicine Peter Shalit, MD, PhD - Internal Medicine
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