November 15, 2012
Fact Sheet 475).
Abacavir is a type of drug called a nucleoside analog reverse transcriptase inhibitor, or nuke. These drugs block the reverse transcriptase enzyme. This enzyme changes HIV's genetic material (RNA) into the form of DNA. This has to occur before HIV's genetic code gets inserted into an infected cell's own genetic codes.
Fact Sheet 404 has more information about guidelines for the use of ART.
Fact Sheet 126 for more information on resistance.
Sometimes, if your virus develops resistance to one drug, it will also have resistance to other ARVs. This is called "cross-resistance."
Resistance can develop quickly. It is very important to take ARVs according to instructions, on schedule, and not to skip or reduce doses.
Abacavir appears to work even when HIV has some resistance to other reverse transcriptase inhibitors.
Abacavir can be taken with food, or between meals.
Abacavir is also available in Trizivir and Epzicom. Trizivir contains zidovudine (Retrovir), lamivudine (Epivir) and abacavir (Ziagen). See Fact Sheet 418 for more information on Trizivir. Epzicom contains lamivudine and abacavir (Ziagen). See Fact Sheet 422 for more information on Epzicom.
Recently, researchers found that a simple blood test can identify patients who might develop the abacavir hypersensitivity reaction. The blood test looks for the HLA-B*5701 gene. This genetic test is now recommended by the FDA before prescribing abacavir. If this test comes back positive, you should add abacavir to the list of medications you are allergic to.
If you have a hypersensitivity reaction, the symptoms will get worse each time you take a dose and will not go away until you stop taking the drug. If you develop any of these symptoms while taking abacavir, call your health care provider immediately. If you have an allergic reaction to abacavir, do not ever start taking it again. A few allergic patients who re-started abacavir had life-threatening reactions.
If you ever stopped abacavir for any reason (for example, because you ran out), talk to your health care provider before you start again. In rare cases, people who thought they weren't allergic had serious reactions when re-starting abacavir.
One large research study suggested that abacavir might increase the risk of heart problems. This seems to only be important for people who are already at high risk of heart problems. You should discuss your risk of heart disease with your health care provider. Recent studies have not confirmed this conclusion.
The triple combination of abacavir plus zidovudine (Retrovir) plus lamivudine (Epivir) should only be used if no stronger regimen is available. The combination of abacavir + tenofovir (Viread) + lamivudine (Epivir) should not be used without additional ARVs.