Emtriva (emtricitabine, FTC)

November 2006     View PDF     En español
Reprinted from www.aidsmeds.com, US

What is Emtriva?
Emtriva is an anti-HIV medication. It is in a category of HIV medicines called nucleoside reverse transcriptase inhibitors (NRTIs). Emtriva prevents HIV from entering the nucleus of healthy T-cells. This prevents the cells from producing new virus and decreases the amount of virus in the body.

Emtriva, manufactured by Gilead Sciences, was approved by the U.S. Food and Drug Administration for the treatment of HIV in 2003.

Emtriva is available in pharmacies as a single drug, which is always combined with other anti-HIV drugs, or in the combination capsules Truvada® (Viread® and Emtriva) and Atripla™ (Viread, Emtriva, and Sustiva® [efavirenz]).

Emtriva is also active against the hepatitis B virus (HBV), the virus responsible for hepatitis B. Although it has not been approved by the FDA for the treatment of hepatitis B, some doctors prescribe it to treat both hepatitis B and HIV. See What is known about side effects? below for more important information regarding Emtriva and hepatitis B.

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What is already known about Emtriva?
For adults, the recommended Emtriva dose is one 200mg capsule once a day. Truvada®, which contains Viread® (tenofovir DF) and Emtriva, needs to be taken once a day.

Emtriva is approved for HIV-positive children 3 months of age and older. The correct dose of Emtriva will depend on the child's weight. The usual dose is 4mg per kilogram of body weight, once a day. If the liquid solution is used (which is easier to give to young children than the adult capsules), the dose should not exceed 240mg per day. If the capsules are used, the dose should not exceed 200mg per day.

The chemical structure of Emtriva looks very much like that of Epivir® (3TC).

Emtriva won't likely be effective for people who have already taken and become resistant to Epivir. This is because one of the key changes, or mutations, in HIV's genetic structure that occurs as a result of Epivir therapy also causes resistance to Emtriva.

Studies have demonstrated that Emtriva is effective for the treatment of HIV when combined with other anti-HIV drugs, usually at least one other nucleoside reverse transcriptase inhibitor (NRTI) and either a protease inhibitor or non-nucleoside reverse transcriptase inhibitor (NNRTI). Emtriva should not be taken alone (as monotherapy) or with just one other anti-HIV drug.

For HIV-positive adults beginning anti-HIV drug therapy for the first time, Emtriva is listed as a "preferred" NRTI option – used in combination with either Retrovir® (AZT) or Viread® (tenofovir) – by the United States Department of Health and Human Services in its treatment guidelines.

Therapy with Emtriva can cause certain changes (mutations) in HIV's structure to occur. Some mutations will prevent Emtriva from working against HIV. The key mutation that causes resistance to Emtriva (the M184V mutation in HIV's reverse transcriptase gene) can cause the virus to be at least partially resistant to other NRTIs, including Ziagen® (abacavir) and Hivid® (ddC), and will likely prevent the NRTI Epivir from working at all against the virus. However, Emtriva resistance might make the virus even more sensitive to other NRTIs, most notably Retrovir (even if HIV has mutations in its structure that would normally cause it to be resistant to Retrovir) and Viread.

Emtriva also appears to be active against the hepatitis B virus (HBV), a virus that can cause liver damage in a small number of people infected by it. Clinical trials are examining the activity of Emtriva against HBV in both patients with and without HIV infection.

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What about drug interactions?
Emtriva should not be taken at the same time as Epivir® or other combination tablets that contain Epivir (for example, Epzicom™, Combivir®, or Trizivir®). This is because both drugs are very similar and it is not believed that combining these two anti-HIV drugs will make a regimen any more effective against the virus.

No other drug interactions have been identified. However, this does not mean that other interactions aren't possible. More research is needed to understand the possible interactions between Emtriva and other medications.

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What is known about side effects?
The most common side effects caused by drug regimens containing Emtriva are headache, diarrhea, nausea, and rash.

Lactic acidosis, which can be fatal, and severe liver problems have been reported in people taking nucleoside reverse transcriptase inhibitors (NRTIs). Contact your doctor immediately if you experience nausea, vomiting, or unusual or unexpected stomach discomfort; weakness and tiredness; shortness of breath; weakness in the arms and legs; yellowing of the skin or eyes; or pain in the upper stomach area.

If you have hepatitis B and HIV and plan to stop taking Emtriva, your doctor might want to frequently check your liver enzymes after stopping treatment. This is because Emtriva is also active against the hepatitis B virus (HBV). If Emtriva is stopped abruptly, it can cause liver disease to "flare" and damage the liver.

Other side effects may occur as a result of taking Emtriva. Be sure to discuss any and all side effects you experience while taking anti-HIV medications with your healthcare provider.

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Can pregnant women take Emtriva?
Emtriva is classified by the FDA as a pregnancy category B drug. Pregnancy category B means that animal studies have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women. HIV-positive women who become pregnant should discuss the benefits and possible side effects of anti-HIV treatment to help protect their babies from HIV.

It is not known whether Emtriva passes into breast milk and what effect they may have on a nursing baby. To prevent transmission of the virus to uninfected babies, it is recommended that HIV-positive mothers not breast-feed.

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What should I tell my doctor before taking Emtriva?
Before taking this medication, tell your doctor if you have: kidney disease or liver disease (including hepatitis B).

Tell your doctors and pharmacists about all medicines you take. This includes prescription medications, over-the-counter products, or herbal/natural remedies.

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Where can I learn more about clinical trials of Emtriva?
If you would like to find out if you are eligible for any clinical trials that include Emtriva, there is an interactive web site run by ACRIA, the AIDS Community Research Initiative of America.

Another useful service for finding clinical trials is AIDSinfo.nih.gov, a site run by the U.S. National Institutes of Health. They have “health information specialists” you can talk to at their toll-free number at 1-800-HIV-0440 (1-800-448-0440.

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