POSITIVELY AWARE MARCH/APRIL 2011
brand name: Retrovir
common name: zidovudine or AZT
class: Nucleoside analog reverse transcriptase inhibitor
(nucleoside analog, NRTI, or nuke)
manufacturer: ViiV Healthcare | www.viivhealthcare.com, (877) 844-8872
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 almost time for your next dose. Do not double up on your next dose. Generic is available.
AWP: $535.12 (generic $365.09) / month for 300 mg tablets, $71.34 (generic $56.42) for 240 ml of 10 mg/ml syrup
Potential side effects and toxicity
May include headache, fever, chills, muscle soreness, fatigue, nausea, and fingernail discoloration. Zidovudine (AZT) 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. Potential exists for severe anemia requiring blood transfusion, erythropoietin injections, or hospitalization when used on its own or in combination with hydroxyurea. Zidovudine/AZT is associated with lipo-atrophy (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. Rare but potentially serious toxicity with all NRTIs: enlarged fatty liver (hepatomegaly with steatosis) and lactic acidosis (accumulation of lactate in the blood and abnormal acid-base balance). Lactic acidosis may cause persistent fatigue, abdominal pain or distension, nausea/vomiting, difficulty breathing or shortness of breath, and enlarged liver.
Potential drug interactions
Do not take with Combivir or Trizivir, since AZT is already in these medications. Biaxin and rifampin (under various brand names) may decrease AZT blood levels. Benemid (probenecid), Dilantin (phenytoin), and Depakote (valproic acid) may increase blood levels and zidovudine clearance of AZT, but no dosing adjustments are recommended. AZT and Zerit should not 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, ribavirin (Rebetol), and with cancer treatments such as hydroxyurea and doxorubicin. Ribavirin may decrease the efficacy of AZT and increase the risk of lactic acidosis. Avoid this combination if possible. Procrit or Epogen warning: if hemoglobin target is above manufacturer’s recommendation (12 g/dL), the risk for serious and life-threatening cardiovascular complications significantly increases. For AZT patients, measure hemoglobin once a week after starting the anemia drugs until hemoglobin has stabilized. Notify health care provider if experiencing pain and/or swelling in the legs, worsening in 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 AZT levels. Monitor for adverse effects.
More information
The not-so-good news for people adding AZT—the fatigue and the potential anemia. 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. 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, MD, MPH
Activist’s comments
The drug that started it all, AZT was despised and feared even as it became the first drug to save lives. The anemia that killed some patients on the early high doses, and the fatigue, dizziness, and lipoatrophy (remember AZT butt?) have largely made this drug a relic of history. That said, it remains a very effective antiviral that some patients continue to tolerate well and it has excellent brain penetration that makes it useful for those with neurocognitive problems. Its long history of safety in pregnancy also makes it an option for women who are pregnant or hoping to conceive. —Jeff Taylor
