Brand name: Trizivir
Generic name: abacavir sulfate (abacavir)/lamivudine/zidovudine, or ABC/3TC/AZT
Class: Nucleoside reverse transcriptase inhibitor (nucleoside, NRTI, or nuke) -- fixed dose combination
Manufacturer: ViiV Healthcare, www.viivhealthcare.com, (877) 844-8872
Standard Dose: One tablet (300 mg abacavir/150 mg lamivudine/300 mg zidovudine), twice a day, with or without food, with no dietary restrictions. Take missed dose as soon as possible, unless it is closer to the time of your next dose. Do not double up on your next dose. Trizivir should not be used in adolescents who weigh less than 88 pounds, people with kidney function less than 50 mL/min, and those with liver disease, because dose adjustments are not possible with the fixed-dose combination.
Potential side effects and toxicity: The most common side effects of Trizivir are the same as those of the drugs it contains -- see Epivir, Retrovir, and Ziagen. Of note is the hypersensitivity reaction (HSR, an allergic-like reaction) warning on abacavir; see Ziagen page. A simple and inexpensive blood test for HLA-B*5701 (a genetic marker) can identify people at high risk for this reaction and virtually eliminate HSR. The HLA-B*5701 test should never be used to diagnose HSR. Do not use a skin patch test to confirm HSR, as the skin test is only used as a research tool. Regardless of the results, it is important to monitor the potential for this reaction. If HSR is suspected or cannot be ruled out, products containing abacavir should be discontinued. If treatment is stopped because of this serious reaction, you can never take products containing abacavir, such as Epzicom or Trizivir, again (called "re-challenging"). Re-challenging can cause a rare life-threatening reaction. (This does not apply to missed doses when there's no HSR, but watch for symptoms if you've stopped the drug for at least a few days). Symptoms usually worsen, very slowly, with every dose. Symptoms usually, but not always, include some combination of fever; muscle ache; severe nausea, vomiting, diarrhea, or abdominal pain; severe tiredness; respiratory symptoms (cough, difficulty breathing, and sore throat); and possible rash. 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. Hypersensitivity might be confused with flu during flu season, but remember that HSR worsens with every dose. Check with your doctor if you have any side effects after taking this medicine -- don't just stop! Some observational studies seemed to indicate that abacavir may increase the risk of cardiovascular events, including heart attacks, in people with greater risk factors (such as smoking, diabetes, high blood pressure, and drug use). One possible explanation was found -- people with kidney problems were put on abacavir in order to avoid Viread (tenofovir), which has potential for kidney toxicity and those people already had a strong risk for heart problems. The FDA conducted an analysis of 26 randomized clinical trials that evaluated abacavir. This analysis did not show an increased risk of heart attacks associated with the use of abacavir. Last year, DHHS HIV treatment guidelines added the statement, "to date, no consensus has been reached either on the association of [abacavir] use with MI [myocardial infarction, or heart attack] risk or a possible mechanism for the association." People who have high risk for heart disease are monitored more closely and the decision to stop or never start a regimen containing abacavir is up to you and your provider. Other side effects associated with Trizivir may include headache, nausea, upset stomach, and fatigue. May be taken with food to decrease potential nausea associated with zidovudine. The zidovudine in Trizivir has been associated with alteration of various cells in the blood through bone marrow suppression, resulting in anemia (low red blood cell counts) and/or neutropenia (low white blood cell counts), particularly during the first three months of therapy in people with advanced HIV. Zidovudine is also associated with lipoatrophy (fat loss in the arms, legs, face, and/or buttocks -- sometimes called "AZT butt"). The lipoatrophy could be irreversible or fat could take a long time to rebuild after changing your regimen. See chart for potential drug class side effects.
Potential drug interactions: See the drugs contained in Trizivir -- Epivir, Retrovir, and Ziagen, for details. Do not take Trizivir with Atripla, Complera, Emtriva, Epivir, Epivir-HBV, Epzicom, Retrovir, Truvada, or Ziagen; all or part of these medications are already in Trizivir or have equivalent medications. If you're taking any of the following medications, consult your doctor or pharmacist before starting Trizivir: Biaxin (clarithromycin), Cytovene (ganciclovir), Daraprim (pyrimethamine), doxorubicin, flucytosine, Fungizone (amphotericin B), hydroxyurea, interferon, probenecid, ribavirin, rifampin, Valcyte (valganciclovir) and Zerit (stavudine). Some of these medications cannot be taken with Trizivir and some may need close monitoring.
More information: See the drugs contained in Trizivir -- Epivir, Retrovir (zidovudine, AZT), and Ziagen. Trizivir is the only triple combination NRTI that has been studied in a randomized, controlled study, which has shown it to be inferior to the standard treatment of two NRTIs plus Sustiva. U.S. treatment guidelines recommend that Trizivir should only be used if other options are not available due to toxicities or drug interactions associated with other HIV regimens. Trizivir contains Epivir, which is used to treat the hepatits B virus (HBV). If you are co-infected with HIV and HBV and you stop Trizivir, your HBV may reactivate and you may experience signs and symptoms of acute HBV. You should be closely monitored by your physician. See package insert for more complete information on potential side effects and interactions.
In the early years of the HAART era, when people were suffering on effective but complex and toxic regimens like Combivir plus Crixivan, Trizivir appeared like a breath of fresh air. Just one pill twice a day, with no need to watch the clock or time your meals, and no kidney stones, diabetes, dry skin, cracked lips, or ingrown toenails to worry about. Sure, some people developed abacavir hypersensitivity reactions (see Ziagen), and many had the usual zidovudine (AZT) side effects (see Retrovir). But compared to what we had before, it seemed almost too good to be true. Well, it was. This "triple-nuke" regimen was shown to be less effective than a regimen containing Sustiva, both at high and low viral loads, and its use declined rapidly after that. Today, if you had some reason to be taking AZT, 3TC, and abacavir, it would make sense to take them in the form of Trizivir. But taking Trizivir alone is no longer recommended.
-- Joel Gallant, M.D., M.P.H.
Although it gave us a sneak peak at therapies to come, this hopeful "one pill, twice a day" triple combination therapy failed to make the mark. Now widely ignored, it is left in the past chapters of history. It helped propel the consumer demand for therapies with less pill burden, but failed to reduce the toxicities.
-- Joey Wynn