Combivir is a formulation of two drugs -- Retrovir (AZT) and Epivir (3TC) -- into one tablet. The two have long been used together, originally as a two-drug combination, and then as the backbone of many three-drug regimens. Retrovir has been available separately since 1987 and Epivir since 1995. When the tablet combining the two drugs was approved by the FDA in September 1997, it was a major step toward simpler dosing. Combivir allows people who are on Epivir and Retrovir to take fewer pills -- two a day instead of the four if you use the individual formulations of each drug. Simpler dosing often leads to better adherence, and therefore may lead to a better antiviral response.
Epivir and Retrovir are both owned by the same company, GlaxoSmithKline. Combivir's introduction in 1997 was the latest in a series of smart marketing moves by Glaxo that helped simplify treatment regimens for people with HIV. Just a year before, in October 1996, the company introduced a 300-mg version of Retrovir to be taken twice a day. The 300-mg tablets essentially replaced the original 100-mg capsules, which at first called for taking one capsule five times a day, then two capsules three times a day, and finally three capsules twice a day. The simplified 300-mg capsule put Retrovir on the same twice-a-day dosing schedule as Epivir (although Epivir can now be taken once a day) and its main competitor, Zerit (d4T). Combining the company's two nucleoside analogs into a single tablet took things one step further. People using Retrovir and Epivir can now take one tablet twice a day for that part of their regimen.
See the Retrovir and Epivir entries for information about side effects, drug interactions, and when to consider Combivir.
Good to Know
- Some physicians may prescribe Combivir because of its easy dosing, even if Retrovir plus Epivir may not be the best two nucleosides for a particular individual.
- Since Combivir is a fixed-dose formulation, people who need a different dose of either drug for whatever reason can't use it.
- People who weigh less than 110 pounds shouldn't take Combivir, since their dose of Epivir needs to be reduced.
- You may not be able to take Combivir if you've had any kidney problems. The dose of Epivir sometimes needs to be lowered in people with kidney problems.
- Combivir shouldn't be taken with Hivid (ddC) because of the interaction between Hivid and Epivir. Nor should it be taken with Zerit because of the interaction between Zerit and Retrovir.
- Epivir, one of the drugs in Combivir, 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 Combivir (see the Hepatitis B section in the discussion of Epivir).
One tablet twice a day, with or without food. Each tablet contains 300 mg of Retrovir (AZT) and 150 mg of Epivir (3TC).
FDA Approval: 1997
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