by Liz Highleyman
January 2004 (Reviewed and Revised December 2005)
Retrovir – brand name
AZT – commonly-used name
zidovudine (ZDV) – generic name
Retrovir belongs to a class of HIV drugs called nucleoside reverse transcriptase inhibitors (NRTIs), also known as nucleoside analogs or “nukes.”
Retrovir and the other NRTIs block reverse transcriptase, a protein that HIV needs to make more copies of itself. This may slow down HIV disease.
The Food and Drug Administration (FDA) has approved Retrovir for use in combination with other HIV drugs for the treatment of HIV infection in adults and children more than three months old.
Retrovir is also approved for use in HIV+ pregnant women and in newborns for six weeks to prevent mother-to-child transmission.
The FDA has granted approval of generic formulations of Retrovir tablets and oral solution (liquid). These versions are available in the U.S.
Retrovir comes in:
- 100 milligram (mg) capsules
- 300 mg tablets
The usual dose for adults is 600 mg taken as one 300 mg tablet twice a day.
- Two 100 mg capsules three times a day
- One 300 mg tablet twice a day
If you have liver or kidney problems, or anemia, your dose of Retrovir may need to be adjusted.
Check with your child’s doctor for children’s dosing.
Retrovir must be used with other HIV medications to treat HIV.
You can take Retrovir with food or on an empty stomach, but taking it with food may cut down on nausea or other side effects.
Many people use Retrovir in combination pills that also contain other NRTI drugs:
- Combivir: Retrovir plus Epivir (lamivudine or 3TC)
- Trizivir: Retrovir plus Epivir plus Ziagen (abacavir)
As with all HIV drugs, it is important to take Retrovir as prescribed. Missing or skipping doses can cause your blood levels of the drug to fall too low and resistance can develop. When your virus becomes resistant to an HIV medication, that drug may stop working.
Retrovir can be used if you are beginning treatment for the first time.
You may be able to use Retrovir if you have developed resistance to another NRTI. In fact, Retrovir may work better if you have Epivir-resistant virus.
Your doctor can run a resistance test to help determine whether Retrovir is likely to work for you.
Retrovir crosses the blood-brain barrier (which protects the brain and spinal cord), so it may be able to fight HIV in the brain.
If your virus develops resistance to Retrovir then it may stop working or not work as well for you. You also may not get as much benefit from some of the other NRTIs.
Sometimes taking more than one medication can cause drug interactions. Taking certain drugs with Retrovir can change the amount of each drug in your blood (including methadone and ribavirin). Your doctor may need to adjust the doses of your drugs to avoid under- or overdosing.
Retrovir and Zerit (stavudine or d4T) should not be taken together.
Several other medications can make the side effects of Retrovir worse. Be sure your doctor knows about all the medications you are taking (including over-the-counter, prescription, street drugs, and herbs), even if you use them only occasionally.
For more information and additional resources to check interactions between the particular drugs you are taking, see our info sheet on drug interactions.
It is not uncommon to experience Retrovir side effects. However, they are likely to be temporary and go away as your body adjusts to the medication. If you experience any of the side effects listed below, call your doctor for advice. Do not just stop taking your medication.
- Loss of appetite
- Fatigue (unusual tiredness)
- Insomnia (trouble falling or staying asleep)
More serious side effects:
- Low white blood cell count (neutropenia) or low red blood cell count ( anemia).
- Myopathy (muscle damage) – this can make your muscles feel achy and weak.
- An increase of lactic acid in the blood ( lactic acidosis), an enlarged and fatty liver, and liver failure have been reported in people using NRTIs. Lactic acidosis is a rare but potentially fatal side effect. Symptoms include nausea, vomiting, or stomach pain; feeling very weak and tired; shortness of breath.
- Lipodystrophy, which may include elevated blood sugar (glucose), elevated lipid levels ( cholesterol and triglycerides), and fat gain or loss in certain areas. The exact causes of lipodystrophy are not known, but may include HIV and/or HIV drugs. It is unclear if Retrovir will cause or impact symptoms of lipodystrophy. For more information on lipodystrophy, see our info sheet.
If you are experiencing persistent, unusual, or serious side effects, call your doctor right away.
Retrovir has been studied in both men and women. Its effectiveness and side effects seem very similar in both men and women. But some research suggests that women are more likely than men to develop liver problems and the rare but very serious side effect, lactic acidosis, while taking NRTI drugs.
As the first HIV drug, Retrovir was originally studied mostly in men. Two early studies of Retrovir alone (monotherapy) in HIV+ people with no symptoms, ACTG 016 and 019, showed that Retrovir delayed progression to AIDS. These studies included 144 women out of a total of 2,048 participants (about 7 percent). An analysis of these studies published in 1991 showed that women were as likely as men to benefit from taking Retrovir.
Another large study of Retrovir monotherapy, called Concorde, included about 1,750 people. There were 263 women (about 15 percent). This study showed that there was no long-term advantage to starting Retrovir early, before symptoms develop.
Since these early trials, Retrovir has been studied in thousands of women, since it is commonly used as part of a combination regimen in studies of other drugs. Retrovir has also been studied in many pregnant women.
The 1994 ACTG 076 study, which included 477 pregnant women with HIV, found that HIV transmission from mothers to their babies was cut by two-thirds when Retrovir was given to the mothers starting in their second or third trimester of pregnancy, then during labor and delivery, then to the baby for six weeks. A later study found that a short course of Retrovir given during late pregnancy and delivery also reduced HIV transmission to babies by about one-half.
Retrovir greatly reduces transmission of HIV from mother to child. Retrovir has been used during pregnancy without any significant negative effect to mother or baby; however, long- term effects on the child are not known.
Retrovir is given to HIV+ pregnant women by the 4th month of pregnancy until their babies are born, and to the newborn baby for six weeks. Women who are not on treatment during pregnancy can still reduce the risk of transmission by taking Retrovir during labor and delivery and by administering Retrovir to the newborn for a short time after birth.
Taking Retrovir alone (monotherapy) is not the best choice for the mother's health because Retrovir resistance may develop. Women with HIV who are pregnant or considering pregnancy should talk to their doctors about treatment options that will be most beneficial for the health of mother and baby.
Click this link for more information on pregnancy.
People who are starting HIV treatment for the first time may develop Immune Reconstitution Syndrome or IRS (also called Immune Reconstitution Inflammatory Syndrome or IRIS). IRS can happen as a result of the immune system getting stronger and responding to an HIV-related infection such as Mycobacterium avium infection (MAC), cytomegalovirus (CMV), Pneumocystis jirovecii pneumonia (PCP), or tuberculosis (TB). People may have been treated for these infections in the past or not even know they have them. If you notice any unusual symptoms soon after starting HIV drugs for the first time, let your doctor know right away so you can be evaluated and, if necessary, treated.
Cadman, J. (1999). Women and HIV: strategies for preventing late-term vertical HIV transmission. Bulletin of Experimental Treatments for AIDS.
Connor, E.M. (1994). Reduction of maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine treatment. New EnglandJournal of Medicine. 331(18). 1173-1180.
Lagakos, S., et. al. (1991). Effects of zidovudine therapy in minority and other subpopulations with early HIV infection. Journal of the American Medical Association, 266. 2709-2712.