Ziagen

The length of this section is meant to be informative, not scary. The most common side effects with an incidence greater than 10% were nausea, headache, malaise (general ill feeling), fatigue, vomiting, and dreams/sleep disorders. In pediatric patients, the more common side effects were fever and/or chills, nausea and vomiting, skin rashes, and ear/nose/throat infections.

Approximately 8% of people who took abacavir in clinical trials (where screening for HLA-B*5701, a genetic marker associated with abacavir hypersensitivity, was not performed) experienced hypersensitivity reaction (HSR), an allergic-like reaction. To minimize the risk for HSR, a simple blood test for HLA-B*5701 should be done prior to starting a regimen containing abacavir to identify people at higher risk for this reaction. This test is covered by most insurance and also by LabCorp/ViiV (go to viivconnect.com). If the HLA-B*5701 test is positive, you are at increased risk for HSR, and should not take abacavir. An allergy to it should be entered in your medical record. A negative HLA-B*5701 test does not mean you won’t have HSR, but the risk is very low (1% from clinical studies). Symptoms of HSR usually include some combination of the following: fever, skin rash, malaise (general ill feeling), severe nausea, headache, muscle ache, chills, diarrhea, vomiting, abdominal pain, respiratory symptoms (cough, difficulty breathing, sore throat), and/or joint pain. Symptoms are listed on the patient information sheet and warning card that you receive each time you fill your prescription. You should keep the warning card with you. HSR might be confused with flu, but symptoms of HSR usually worsen, very slowly, and with every dose.

People who think they are experiencing HSR must be evaluated by an experienced HIV provider right away before they stop taking abacavir. Do not use a skin patch test to confirm HSR. Symptoms usually resolve after permanent discontinuation. If you develop HSR, abacavir should be stopped and you can never take abacavir or any product containing abacavir (Epzicom, Ziagen, or Triumeq) again (starting again is called rechallenging). Rechallenging can cause a rare life-threatening reaction. This does not apply to a missed dose when there is no HSR, but talk with your healthcare provider and watch for symptoms if you’ve stopped the drug for a few days, preferably under the observation of others who can call for medical help if you develop symptoms. An HSR can technically occur at any time, regardless of how long you have been taking the medication; however, it is much more likely to occur when you start (or re-start) the medication (90% occur within the first 6 weeks of treatment).

Some large observational studies suggest abacavir may increase the risk of cardiovascular events, including myocardial infarction (MI, or heart attack), in people with risk factors (such as older age, smoking, diabetes, uncontrolled high blood pressure, high cholesterol, family history of heart disease, and drug use), especially within the first 6 months of therapy. However, other studies, including a large meta-analysis, have shown no increase in cardiovascular risk. To date, no absolute consensus has been reached on the association of abacavir with cardiac risk or a possible mechanism for the association. People who are at high risk for heart disease should discuss risks with their provider and they should be monitored more closely.

Alcohol can increase abacavir levels and therefore can increase the possibility of side effects.

The ACTG A5202 study found that abacavir/lamivudine (Epzicom) was inferior to tenofovir/emtricitabine (Truvada) in getting people undetectable when their pre-treatment viral load was over 100,000 copies/mL. However, when combined with Tivicay (dolutegravir), Epzicom performed just as well as Truvada in people with high viral loads (over 100,000 copies/mL). Hence, Triumeq is the only abacavir-containing regimen recommended by DHHS as initial therapy for most HLA-B*5701 negative people. It is recommended people with symptoms of acute respiratory disease consider HSR even if another diagnosis such as pneumonia, bronchitis, or flu is possible. But again, a simple test reveals whether you are at high risk for the allergic reaction. FDA researchers reported finding a mechanism for autoimmune drug reactions, including abacavir HSR, and hope it helps improve drug safety in the future. Ziagen as part of the combination tablet Epzicom is recommended by DHHS as one of the preferred NRTI combination components of an ART regimen during pregnancy.

Dr. Melanie Thompson:

Had abacavir been developed five years later, it might have been abandoned because of its hypersensitivity syndrome. Intensive scientific effort, however, quickly identified HLA B*5701 as the genetic marker associated with the syndrome, and now a simple screening lab makes it possible to largely avoid this potentially serious side effect. But the need for this one-time screening lab before starting abacavir prohibits its use in rapid ART start regimens.

The hypersensitivity syndrome includes fever, often rash, fatigue, and a variety of other symptoms ranging from respiratory to gastrointestinal. It generally occurs within the first six weeks of starting the drug and can be serious or fatal if the drug is restarted after an initial reaction. People who have had abacavir hypersensitivity should never take it again.

There has been controversy for years about whether abacavir causes or worsens cardiovascular disease, with large studies showing contradictory results. Major guidelines panels including DHHS and IAS-USA agree that the drug should be avoided by people with known cardiovascular disease and those who are at high risk.

Because abacavir is now generic, and generally coformulated with 3TC (Epzicom) or dolutegravir and 3TC (Triumeq), branded Ziagen is rarely used.

It is available as a liquid for people who are unable to swallow pills, or who need dose reduction due to liver disease.

Activist Bridgette Picou:

Ziagen, better known as abacavir, it is not intended to be taken alone, but as part of a full regimen. There are potentially harmful, even fatal, reactions associated with abacavir if not checked. There is a blood test for hypersensitivity you should have before use; monitor how you feel once you start Ziagen. If you feel an allergy developing, or just aren’t sure you feel right, stop the medication and consult your clinician. You will be tested for lactic acidosis, which is a buildup of acid in the blood.