Pronunciation(s): ZEYE-uh-jen; uh-BACK-ah-veer
|What is abacavir?
- Abacavir is an HIV medication. It is in a category of HIV medications called nucleoside reverse transcriptase inhibitors (NRTIs). Abacavir prevents HIV from altering the genetic material of healthy CD4 cells. This prevents the cells from producing new virus and decreases the amount of virus in the body.
- Abacavir was approved for the treatment of HIV by the U.S. Food and Drug Administration (FDA) in 1998. Ziagen, the brand-name version of abacavir, is sold in the U.S. by ViiV Healthcare. Generic abacavir is sold in the U.S. by various manufacturers.
- Ziagen and generic abacavir are available in pharmacies as a single drug. Abacavir is also available in combination tablets, notably Epzicom. Each Epzicom tablet contains a single dose of abacavir and lamivudine.
- A patient assistance program (PAP) has been established for people living with HIV who do not have private or public health insurance and are unable to afford brand-name Ziagen. To learn more about the PAP for Ziagen, call 877-784-4842 or refer to the program's website for more information. For those with private health insurance, GSK has established a program to help cover each Ziagen co-payment, up to $100 every month. To learn more about this co-pay program, check out mysupportcard.com.
What is known about abacavir?
- Abacavir can be taken once a day or twice a day. Once-a-day dosing requires taking two 300mg tablets every 24 hours. Twice-a-day dosing requires taking one 300mg tablet every 12 hours. Epzicom tablets, containing abacavir and lamivudine, are taken once a day.
- For children, a scored tablet and a liquid formula of Ziagen are available. The correct dose depends on the child's body weight and will change as the child gets older. To learn about treatment options for children, click here.
- Abacavir can be taken with or without food.
- Numerous studies have demonstrated that abacavir is effective for the treatment of HIV when combined with other HIV drugs, though it may be reserved for people living with HIV starting HIV treatment with viral loads below 100,000 copies/mL. Abacavir should not be taken alone (as monotherapy) or with just one other HIV drug.
- For HIV-positive adults beginning HIV drug therapy for the first time, abacavir can be used as a component of recommended drug combinations established by the United States Department of Health and Human Services in its treatment guidelines. To learn more about these recommendations and options, click here.
- Therapy with abacavir can cause certain changes (mutations) in HIV's structure to occur. Some mutations will prevent Ziagen from working against HIV. Some of these mutations can also prevent zidovudine and/or lamivudine from working against HIV. Similarly, abacavir might not work well against HIV strains already resistant to zidovudine and/or lamivudine. If your viral load does not go undetectable or becomes detectable (and increases) while you are taking an HIV drug regimen that contains abacavir, your doctor can order a drug-resistance test to determine if your HIV has mutations that are causing resistance to abacavir and to help you figure out which NRTIs your HIV is still sensitive to.
What about drug interactions?
- Abacavir should not be taken at the same time as Epzicom or Trizivir.
- The protease inhibitor Aptivus (tipranavir) can decrease the amount of abacavir in the blood. The appropriate doses for this combination have not been established.
- Abacavir can increase the rate at which methadone, a drug often used to help manage symptoms of heroin withdrawal, is cleared from the body. If you are taking methadone and abacavir at the same time, it might be necessary to increase your methadone dose.
What about side effects?
- Approximately 5 percent of people who take abacavir are allergic to it and can experience a "hypersensitivity reaction." This can be serious and may require that abacavir therapy be stopped. A hypersensitivity reaction usually appears during the second week of therapy, but it can take as long as six weeks to notice any symptoms. The most common symptoms are fever and rash, followed by headaches, stomach upset, feeling tired, sore throat, cough, and shortness of breath. These symptoms usually get worse over time and it is important that you report them to your doctor immediately.
An inexpensive laboratory test is available to look for an inherited gene, called HLA-B*5701, that has been linked to the hypersensitivity reaction in HIV-positive people taking abacavir. While not all people with this gene experience an allergic reaction while taking abacavir, most do. In turn, if you are tested and found to have this gene, abacavir (or other medications containing abacavir) should either be avoided or used with caution. If you and your doctor are thinking about starting Ziagen or another abacavir-containing medication for the first time, be sure to discuss this genetic test.
- If your doctor tells you that you are allergic or are having a hypersensitivity reaction, you will be told to stop the drug. If you stop taking abacavir because of these symptoms, you must not start the drug again, or start any drug that contains abacavir (e.g. Epzicom). Some people who were allergic to the drug and restarted therapy saw their symptoms return immediately and became very ill.
- Lactic acidosis, which can be fatal, and severe liver problems have been reported in people taking NRTIs including abacavir. 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.
- Some of the more common side effects include appetite loss, headaches, feeling crummy (malaise), nausea, vomiting, and diarrhea. Very often, these side effects improve within a few months/weeks of starting abacavir.
- HIV drug regimens containing NRTIs, including abacavir, can cause increased fat levels (cholesterol and triglycerides) in the blood, abnormal body-shape changes (lipodystrophy; including increased fat around the abdomen, breasts, and back of the neck, as well as decreased fat in the face, arms, and legs), and diabetes. These side effects of HIV drug therapy are reviewed in our lessons on Lipodystrophy, Facial Lipoatrophy, and Risks To Your Heart (Hyperlipidemia).
- Taking medications that include abacavir may increase the risk of a heart attack. The reason for the increased risk associated with abacavir, compared with other NRTIs, has not been established. The risk of a heart attack is highest among people living with HIV taking abacavir who have other cardiovascular disease (CVD) factors, including high blood pressure, high lipids, diabetes, cigarette smoking, family history of CVD.
Can pregnant women take abacavir?
- Abacavir is classified by the FDA as a pregnancy category C drug. Pregnancy category C means that animal studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks. HIV-positive women who become pregnant should discuss the benefits and possible side effects of HIV treatment to help protect their babies from HIV (see our lesson called Family Planning, Pregnancy & HIV).
- It is not known whether abacavir passes into breast milk and what effects it may have on a nursing baby. However, to prevent HIV transmission of the virus to uninfected babies, it is recommended that HIV-positive mothers not breast-feed.
Who should not take abacavir?
- Before taking this medication, tell your doctor if you have kidney disease or liver disease.
- You may not be able to take abacavir, or you may require lower doses or special monitoring during treatment, if you have any of these conditions.
- Be sure to tell your doctor if you have allergies to medications, including abacavir. If you've ever taken abacavir in the past and stopped the drug for any reason, be sure to tell your doctor. If you have ever taken abacavir, or any drug that contains abacavir (e.g. Epzicom), in the past and had a hypersensitivity reaction, you must not take abacavir again.
Where can I learn more about clinical trials that are using abacavir?
- If you would like to find out if you are eligible for any clinical trials that include abacavir, visit ClinicalTrials.gov, a site run by the U.S. National Institutes of Health. The site has information about all HIV-related clinical studies in the United States. For more info, you can call their toll-free number at 1-800-HIV-0440 (1-800-448-0440) or email firstname.lastname@example.org.