Brand name: Retrovir

Common name: AZT, zidovudine

Class: nucleoside analog (also called nucleoside reverse transcriptase inhibitor, NRTI or nuke)

Standard dose: One 300 mg tablet twice a day (two 100 mg capsules three times a day also available), no food restrictions. Clear, strawberry-flavored liquid available for pediatric use. Take missed dose as soon as possible, but do not double dose.

Wholesale cost: $4,013/yr., $334/month

Patient assistance number: 1 (800) 722–9294, www.gsk.com

AIDS Treatment Information Service: 1 (800) HIV–0440 (448–0440)

Potential side effects:

Headaches, fever, chills, muscle soreness, fatigue, anemia, nausea, and fingernail discoloration. AZT has been associated with bone marrow suppression: anemia and/or neutropenia, particularly in people with advanced HIV. Potential for severe anemia requiring blood transfusion or hospitalization when used with hydroxyurea. Prolonged use of AZT has been associated with symptomatic myopathy (muscle damage). Rare but potentially fatal toxicity with all NRTIs: pancreatitis (signs include nausea, vomiting, and abdominal pain that often spreads to the chest and back); lactic acidosis (seen mostly in women, especially obese women; greater risk for people with underlying liver disease; signs include deep muscle fatigue, especially in legs, and difficulty breathing); and enlarged, fatty liver (called hepatomegaly with steatosis; check for tenderness below ribs on right side).

Potential drug interactions:

Biaxin (clarithromycin), Mycobutin (rifabutin), and rifampin (under various brand names, used for treating tuberculosis) may decrease AZT blood levels. Benemid (probenecid) may increase AZT blood levels and decrease AZT clearance. Methadone and ganciclovir (Cytovene and Vitrasert) increase AZT blood levels. Prescriber may need to adjust doses accordingly. AZT and Zerit shouldn’t be used together due to evidence that one limits the other’s bioavailability level in the test tube. Also, risk of bone marrow toxicity may increase with use of ganciclovir, amphotericin B, pentamidine (NebuPent, Pentam or Pentacarmat), dapsone, flucytosine, interferon-alpha ribavirin (Rebetol), and with other antineoplastics (anti-tumor treatment) such as hydroxyurea. Ribavirin and AZT may cancel each other out.

Tips:

Do not use with Hydrea (hydroxyurea). Retrovir has somewhat of a bad rep left over from its early years when the doses given were too high. Studies show that Retrovir crosses the blood-brain barrier to a useful degree, which may treat or prevent neurologic damage (such as dementia). Proven to significantly reduce mother-to-infant transmission. Also available in Combivir (one tablet twice a day, combined with Epivir) and in a triple combination in Trizivir (one tablet twice a day combined with both Epivir and Ziagen).

Manufacturer

FDA-approved in March 1987, Retrovir (AZT) was the first authorized antiretroviral AIDS drug. Together with 3TC, Retrovir is one of the most widely used anti-HIV drugs and has become a staple in many three-drug studies for the treatment of HIV/AIDS. Epivir and Retrovir are available together as a fixed dose combination tablet called Combivir. They are also combined with abacavir in a fixed dose combination tablet called Trizivir. The combination of 3TC and Retrovir was generally well tolerated in clinical trials. The most commonly reported adverse events consisted of headache, nausea, malaise and fatigue, runny nose and nasal congestion, diarrhea, low white blood cells and anemia. Its labeled dosing is one 300 mg tablet twice daily. Studies have shown Retrovir to be effective in significantly reducing the risk of transmission of HIV from an infected mother to her baby. Please refer to the full prescribing information for additional important safety information.

—GlaxoSmithKline

Doctor

FDA approved 3/19/87 for the treatment of adult AIDS or symptomatic HIV. Approved 9/28/89 in syrup formulation. Approved 2/2/90 in intravenous form. Approved 5/3/90 for pediatric HIV infection (ages 3 months to 12 years). Approved 8/8/94 for the prevention of perinatal transmission in HIV pregnant women and newborns. The first drug approved to treat AIDS, the well known zidovudine was created as a potential treatment for cancer. ZDV is metabolized to its active triphosphate metabolite (74% eliminated through the urine). There is cross-resistance between ZDV and other NRTIs. Its peak effectiveness is in treatment naïve patients as part of a combination regimen. Rash, nausea, headache, bone marrow toxicity (anemia), myopathy, lactic acidosis and hepatomegaly with steatosis have been reported. Concomitant nephrotoxic, cytotoxic or myelosuppressive drugs should be used with caution (e.g., amphothericin B, vincristine, gancyclovir).

—Carlos H. Zambrano, M.D.

Activist

AZT (also known as Retrovir) was the first drug approved for AIDS in 1987; therefore, there is more experience with AZT than any other AIDS drug. It was initially dosed at 1200-1500 milligrams a day, the reason it has such a bad reputation. Later lower doses, 500-600 mg. a day, were found to be better tolerated and just as effective. Recognized as the standard of care for years, some doctors and patients have chosen to use other similar nucleoside analogs instead because AZT can cause nausea and headaches. Resistance tests should be performed in making initial treatment decisions because 10% of newly infected people are resistant to AZT.

Before use in HIV, AZT was shelved as a drug for cancer. After approval for HIV, ACT UP New York closed the New York Stock Exchange in a civil disobedience action over the high price of the drug. Two weeks later, the prices were lowered.

—Matt Sharp