Study: Lower doses of AZT show limited effectiveness

BOSTON, Massachusetts (Reuters) -- Lower doses of AZT given to HIV-infected mothers and infants impede the transmission of the AIDS virus from parent to child, but still do not work as well as higher levels of the drug, researchers reported in Thursday's New England Journal of Medicine.

The study, funded by the drug's maker Glaxo Wellcome was designed to find out if lower and less expensive dosages of AZT might reduce the number of AIDS babies in developing countries.

The research is expected to have little effect on medical care in developed countries, where combination drug therapies have replaced AZT-only treatment for AIDS.

Sales of AZT have dropped significantly since the adoption of such therapies in the West, said PaineWebber analyst Jeff Chaffkin, who follows Glaxo Wellcome Plc.

"Although there is still a need for AZT in developing countries, they don't have the resources to pay for it," Chaffkin said.

In tests where some mothers and newborns received scaled-back therapy, Dr. Marc Lallemant and his colleagues found the shortened drug regimen for both the pregnant mother and her newborn doubled the risk that a baby would be born with the AIDS virus, compared to volunteers and their babies who received the full treatment.

They also found that only 1.6 percent of the women who got the full dose of AZT beginning at the 28th week of pregnancy had babies infected with the AIDS virus, compared with a rate of 5.1 percent when the mother's AZT therapy began in the 35th week.

But if the mother was unable to get the full 11-week treatment before giving birth, it was better to give a full six-week dose of AZT to the newborn, instead of just three days of AZT therapy, the Lallemant team concluded.

In an editorial, doctors Catherine Peckham and Marie-Louise Newell of the Institute of Child Health in London said doctors in developing countries not only lacked the resources to treat infected women, but "there is the additional challenge of preventing transmission (of the AIDS virus) through breast-feeding without jeopardizing the health of the child."

The study's design drew praise from Public Citizen, a U.S. consumer health group that has criticized the use of placebo pills in previous attempts to find less-expensive ways to prevent the spread of AIDS in developing countries.

Public Citizen and others have characterized the practice as unethical. Doctors involved in those studies have defended the work by noting that their volunteers would not have received AZT treatment anyway.

"Unlike more than a dozen other studies that provided at least some pregnant women with either placebos or treatments not proven to be effective, this study provided AZT to all pregnant women," said Dr. Peter Lurie, deputy director of Public Citizen's Health Research Group. "It shows you can have the best ethics and the best science."

Copyright 2000 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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New England Journal of Medicine

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