Trizivir is not a single drug, but a formulation of three drugs into one tablet. All three drugs -- Retrovir (AZT), Epivir (3TC), and Ziagen (abacavir) -- continue to be available separately.

Background

The FDA approvals of Combivir (Retrovir and Epivir in one tablet) in 1997 and Ziagen in 1998 paved the way for Trizivir's approval in November 2000. Retrovir, Epivir, and Ziagen are all owned by GlaxoSmithKline, so it made sense from a commercial viewpoint to combine the drugs into one tablet.

Based on study results (see CNA3005 and, especially, ACTG 5095 described under Ziagen), using Trizivir -- at least without a fourth drug -- might not be a good idea for people who are just starting HIV therapy. This triple-nucleoside regimen doesn't lower viral load as much or for as long as a regimen that combines two nucleosides with a protease inhibitor (PI) or non-nucleoside (NNRTI); people with viral loads greater than 100,000 don't respond well to this regimen; and there's the potential for a Ziagen hypersensitivity reaction. On the positive side, Trizivir offers easy dosing, has few interactions with other drugs, saves PIs and NNRTIs for future use, and avoids some of the side effects associated with PIs and NNRTIs. So it may still be a useful option for people with HIV who face adherence difficulties. But the potential benefits may be outweighed by the potential risks.

The recently revised Department of Health and Human Services treatment guidelines list Trizivir as an alternative to a PI- or NNRTI-based regimen for people who have never taken antiretrovirals before, but caution that it should not be used by people with viral loads greater than 100,000. The July 2003 British HIV Association (BHIVA) treatment guidelines go even further, stating that Trizivir should not be considered for initial therapy and that it should only be used with an additional drug in a four-drug combination.

As Trizivir's role is re-evaluated in people who are just starting therapy, it remains useful for some people who have run out of treatment options and are faced with the prospect of taking four, five or more antiretrovirals, including some that they've developed at least partial resistance to in the past. Using Trizivir in a mega-combination adds three drugs to the regimen without adding too much to the pill burden. Other people who are doing well on a PI or NNRTI regimen may benefit by switching to Trizivir, hopefully maintaining low viral loads and high CD4 counts and reducing -- or at least not increasing -- some of the metabolic changes associated with the PIs and NNRTIs.

See the Retrovir, Epivir, and Ziagen entries for information about side effects, drug interactions, and other particulars.

Good to Know

• Some physicians may prescribe Trizivir based on assumptions about an individual's inability to adhere to a more complex regimen even though another regimen may be more beneficial. Trizivir still requires twice-daily dosing, and almost all regimens can now be taken twice a day or once a day. Trizivir isn't necessarily any less challenging to adhere to than other, more powerful regimens.

• Because Trizivir is a fixed-dose formulation, it can't be used by people who require a different dose of any of the three drugs it contains.

• People who weigh less than 110 pounds shouldn't take Trizivir, since their dose of Epivir needs to be reduced.

• You may not be able to take Trizivir if you've had any kidney problems. The dose of Epivir sometimes needs to be lowered in people with kidney problems.

• People starting Trizivir may not be aware of the potentially life-threatening hypersensitivity reaction that occurs in about 5% of people who take Ziagen. Some may not be aware that Trizivir contains Ziagen. Educate yourself about the symptoms of a hypersensitivity reaction (see Ziagen entry). If you suspect that you're experiencing Ziagen hypersensitivity, call your doctor immediately. Some people who took Ziagen in the past may have experienced a hypersensitivity reaction without recognizing it. If they take Trizivir, they should be aware that it's the same as re-starting Ziagen.

• Epivir, one of the drugs in Trizivir, is also used as a treatment for chronic hepatitis B (HBV), although at a lower dose than that used for HIV. People co-infected with HIV and chronic HBV need to bear that in mind when considering Trizivir (see the Hepatitis B section in the discussion of Epivir).

Dose

One tablet twice a day, with or without food. Each tablet contains 300 mg of Retrovir (AZT), 150 mg of Epivir (3TC), and 300 mg of Ziagen (abacavir).

FDA Approval: 2000

Manufacturer: GlaxoSmithKline

Patient Assistance Program: 866-728-4368