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The Food and Drug Administration today approved the anti-AIDS drug AZT (zidovudine) for use in preventing transmission of HIV, the virus that causes AIDS, from HIV-infected pregnant women to their babies.
Data supporting the new indication comes from a federally sponsored study designed to determine whether AZT reduces the risk of passing the HIV virus from infected mothers to their infants either before or during birth.
In this randomized, placebo-controlled trial, HIV-infected women received 500 mg of AZT per day orally during pregnancy and a continuous intravenous infusion of AZT during labor. Therapy was begun between 14 and 34 weeks after conception. Newborns received oral AZT within 24 hours after birth and for six weeks thereafter. The study did not treat women during the first trimester of pregnancy. Also, women with prior use of AZT or CD4 counts below 200 were not eligible for the study.
The study was halted when a planned interim review of the data showed that for women treated with AZT the estimated rate of transmitting the virus to their babies was reduced by approximately two-thirds, from 25.5 percent infected babies from women on placebo to 8.3 percent infected babies from women on the AZT regimen. A long-term follow-up study of babies exposed to AZT is under way.
The drug was well tolerated by both mothers and infants. Side effects reported during the study included reversible mild anemia in some infants.
On July 28, FDA's Antiviral Drugs Advisory Committee reviewed the application to amend the AZT label and unanimously recommended that the agency approve this amendment.
With today's approval, AZT is now indicated for the prevention of maternal-fetal HIV transmission as part of a regimen that includes oral AZT beginning between 14 and 34 weeks of gestation, intravenous AZT during labor, and administration of AZT syrup to the newborn after birth.
AZT is manufactured by the Burroughs Wellcome Co. of Research Triangle Park, N.C. and is marketed under the trade name Retrovir.