WEDNESDAY, Oct. 13 (HealthDay News) -- New research suggests that alternative drug regimens in poor countries could help HIV-infected mothers and their infants more effectively fight off the virus that causes AIDS.

Currently, doctors lower the risk of transmission of mother-to-baby HIV infection by giving a drug to mothers right before birth and to babies right after. About half of the babies avoid getting HIV, but mothers and babies who do get infected often develop resistance to the drug, which is typically given to them later in life.

Enter the alternatives. "We now have a very effective treatment for women who've taken a specific drug and for babies at risk," said Dr. Shahin Lockman, lead author of one of two studies about the regimens in the Oct. 14 issue of the New England Journal of Medicine.

There's a big hitch, however: the alternative regimens are much more expensive than the current drug regimen, although the study authors weren't able to give an estimate of the difference in costs between the regimens.

At stake are the lives of hundreds of thousands, perhaps millions, of women who are infected with HIV, said Lockman, an assistant professor at Harvard Medical School.

In many cases, HIV-positive women in poor countries -- such as those in Africa -- receive treatment with the inexpensive anti-HIV drug nevirapine shortly before they give birth. The idea is that the drug will reduce the risk that the baby will become infected with HIV during labor and delivery.

The problem is that in some cases, the AIDS virus develops resistance to the drug and the drug then doesn't work as well after an initial treatment. Even so, nevirapine is still used to treat both mothers and infected babies after birth.

Researchers have been looking for alternative treatments that have less risk of failing because the virus can escape the drug's effects. In the new studies, they tested different regimens, trying to find the ones that will allow more mothers or babies to push the level of HIV in their blood to zero. (They won't be cured if that happens, but they will stave off the development of the disease.)

In one study, researchers gave either of two treatments to 241 African women who'd taken a single dose of nevirapine at least six months earlier. Twenty-six percent of those who took a regimen that included nevirapine either died or failed to beat back the virus, compared to 8 percent of those who took the other regimen. The regimens were nevirapine plus tenofovir-emtricitabine or ritonavir-boosted lopinavir plus tenofovir-emtricitabine.

In the other study, researchers tested two regimens -- zidovudine and lamivudine plus nevirapine, or zidovudine and lamivudine plus ritonavir-boosted lopinavir -- in HIV-infected babies aged 6 months to 3 years. Only about 60 percent of the babies on the nevirapine regimen managed to both beat back the virus and survive, compared to about 78 percent of the other babies.

The results in the babies were so clear that the researchers ended their study early. Another study, which hopes to determine the best treatment for infected babies who didn't get nevirapine at birth, is continuing.

Nevirapine by itself is inexpensive, but many pregnant mothers in poor countries still aren't given it to prevent transmission to their babies, said Dr. Paul E. Palumbo, lead author of the second study and director of the International Pediatric HIV Program at Dartmouth-Hitchcock Medical Center.

The cost will be a big challenge to providing the alternative regimens, both researchers say. "When you're already struggling to provide drugs and then you goose the cost dramatically by changing the regimen, it really requires a lot of creativity and problem-solving," Palumbo said. "It could take years for even the beginning of implementation, and many years before it's more comprehensively implemented."

Still, Lockman -- the lead author of the study of mothers -- said there's a "moral and ethical obligation to try to help the mothers who put their health on the line to prevent their babies from getting infected."

As for nevirapine, it is problematic but remains "a very useful drug, and there are many solutions to this problem," said Dr. Marc Lallemant, an AIDS specialist at Harvard School of Public Health and co-author of a commentary accompanying the study. "The bottom line is that it is an absolute priority to avoid HIV infection in children in the first place."

More information

Avert.org has details about mother-to-child HIV transmission.