That's certainly the case with AZT , the original weapon against HIV and perinatal transmission. As time goes on, we're getting a better picture of how AZT works. For one thing, the drug is stockpiled in the blood of the umbilical cord, building up to high concentrations that help control the virus in the blood the mother supplies to the fetus. The news isn't that surprising, since AZT belongs to a class of drugs that's designed to elbow its way inside genetic material. But the fact that the drug turned up in fetal monkey livers, lungs, hearts, and brain cells after just three hours of maternal exposure is worrisome.
Some researchers say changes in DNA open the door to cellular mutations and even cancer.
Last year brought encouraging news that an inexpensive single dose of nevirapine to both mother and child lowered transmission rates significantly. That's especially good news for women in sub-Saharan Africa and other developing areas of the world where the cost of six weeks of AZT, let alone ongoing treatment with combination therapy, is simply too high. Here, women have access to care, albeit uneven. It's too early to say whether late-stage nevirapine will be a useful addition to other regimens. But there are risks.