Brand name: Retrovir

Generic name: zidovudine, or AZT, or ZDV

Class: Nucleoside reverse transcriptase inhibitor (nucleoside, NRTI, or nuke) -- fixed dose combination

Manufacturer: ViiV Healthcare,, (877) 844-8872

AWP: $535.12 (generic $309.89)/month for 300 mg tablets, $71.34 (generic $56.42) for 240 mL of 10 mg/mL syrup

Standard Dose: One 300 mg tablet twice a day (12 hours apart); two 100 mg capsules three times a day (8 hours apart) also available; with or without food, with no dietary restrictions. Clear, strawberry-flavored liquid available for infants four weeks of age and up; dose is weight-based. 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. If your kidney function is less than 15 mL/min or you are on dialysis, your dose will need to be adjusted. Used in pregnancy and for newborns to prevent HIV transmission from mother to child. Generic is available.

Potential side effects and toxicity: May include headache, fever and chills (more common in children), muscle soreness, fatigue, nausea, and fingernail discoloration. Zidovudine (Retrovir) has been associated with alteration of various cells in the blood through bone marrow suppression, resulting in anemia (low red blood cell counts), which can make you feel short of breath and tired, and/or neutropenia (low white blood cell counts), which can increase your risk for getting colds and other infections, particularly during the first three months of therapy in people with advanced HIV. Potential exists for severe anemia requiring blood transfusion, erythropoietin injections, or hospitalization when used on its own or particularly if used in combination with hydroxyurea. Your provider may check your blood in the first 4-6 weeks after you start zidovudine and will look for anemia and neutropenia. Zidovudine is associated with lipoatrophy (fat loss of 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 your HIV regimen is changed. See chart for potential drug class side effects.

Potential drug interactions: Do not take with Combivir or Trizivir, since zidovudine is already in these medications. Biaxin and rifampin (under various brand names) may decrease zidovudine blood levels. Do not take with the cancer treatment doxorubicin. Benemid (probenecid), Dilantin (phenytoin), and Depakote (valproic acid) may increase blood levels and decrease clearance of zidovudine, but no dosing adjustments are recommended. Zidovudine and Zerit (stavudine) should never be used together due to evidence that one limits the other's effectiveness. Also, bone marrow suppression should be monitored with use of Cytovene (ganciclovir), Valcyte, amphotericin B, pentamidine, dapsone, flucytosine, sulfadiazine, interferon-alpha, and ribavirin (Rebetol). Ribavirin (used with interferon to treat hepatitis C) may decrease the efficacy of zidovudine and increase the risk of lactic acidosis and should not be used together. For patients taking zidovudine, measure hemoglobin once a week after starting other medications that can cause anemia until hemoglobin has stabilized. Notify your health care provider if you're experiencing pain and/or swelling in the legs, worsening or shortness of breath, increases in blood pressure, dizziness, or loss of consciousness, extreme tiredness, or blood clots in hemodialysis vascular access ports. Methadone can increase zidovudine levels but no dose adjustments are recommended. Monitor for adverse effects.

More information: Zidovudine is rarely used nowadays, though it remains the go-to medication for pregnancy and infants after birth, to prevent mother-to-child transmission. The not-so-good news for people adding zidovudine -- the fatigue and the potential anemia, but it is still a very good HIV medication with many years of data behind it and a good option for people who have developed resistance to some of the newer first-line HIV medications. You can start taking erythropoietin (Procrit or Epogen) for some anemias, but that's adding an expensive weekly injectable. Some doctors would prefer switching out the zidovudine for another drug if you have other options. Taking with food may minimize upset stomach. Zidovudine crosses the blood-brain barrier to a useful degree, which may be beneficial for patients at risk for neurological damage (such as dementia) from HIV. Thanks to extensive data, zidovudine is a preferred drug for pregnant women who are taking therapy for the first time, according to U.S. HIV treatment guidelines. See package insert for more complete information on potential side effects and interactions.

Doctor's Comments

Retrovir (AZT) was the first drug approved for the treatment of HIV, and while its benefits were modest and temporary, it did make a difference for many people. It enjoyed two revivals, first with the approval of Combivir (AZT plus 3TC) and later with the approval of Trizivir (AZT plus 3TC plus abacavir). However, the use of AZT in any form has declined with the approval of safer, more convenient, and more effective alternatives. AZT must be taken twice a day and can cause anemia, nausea, fatigue, and lipoatrophy. In fact, while AZT may not cause lipoatrophy as often or as quickly as Zerit (d4T) does, there's some evidence that lipoatrophy caused by AZT may be less reversible. Because of its long history of safety in pregnancy, AZT remains a preferred nucleoside for pregnant women, though there is growing comfort with the use of other agents.

-- Joel Gallant, M.D., M.P.H.

Activist's Comments

The grandfather of HIV drugs, it has morphed over the years to stay relevant. The only real application for AZT these days is for use in mother-to-child transmission prevention, as it is safe for pregnancy. AZT is probably still in wide use in other countries, as less costly generics are available in most markets. AZT has been relegated to second or third string for most prescribers. To be fair, it remains one of the few effective antivirals that cross the blood/brain barrier, achieving CNS penetration, which makes it useful for those with neurocognitive problems.

-- Joey Wynn

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