HIV-positive women given a single dose of nevirapine during labor to prevent mother-to-baby transmission face an increased risk of resistance to the drug and premature death if later treated with a regimen containing nevirapine, researchers said recently. About 100,000 women annually receive nevirapine during childbirth in South Africa.

The study, funded by the US National Institutes of Health, included 745 women in seven African countries and compared AIDS drug cocktails between two groups of women: those who received nevirapine during labor and those who did not.

A routine interim safety review on Oct. 6 found that women who received nevirapine fared better on a nevirapine-sparing cocktail (lopinavir-boosted ritonavir, emtricitabine, and tenofovir). Of the 13 women with nevirapine-resistant HIV strains who received a cocktail including nevirapine (nevirapine, emtricitabine, and tenofovir), five (38 percent) either died or failed to control their virus. All 12 women with nevirapine-resistant HIV who took the nevirapine-sparing regimen were alive and had suppressed the virus.

The independent safety review board recommended stopping this part of the trial, and researchers have begun notifying participants of the findings. Another part of the study, comparing the efficacy of nevirapine and lopinavir-boosted ritonavir in women not exposed to nevirapine, continues.

Nevirapine resistance can be avoided by giving women a cheap, seven-day course of Combivir after their babies are delivered, researchers said.

"I'm not saying nevirapine should not have been given to these women -- it was the best we had at the time," said the study's Dr. Francesca Conradie of the University of Witwatersrand. "What we can do now is protect nevirapine (to ensure it can be safely used in their subsequent treatment)."

Women who were given single-dose nevirapine should be closely monitored for resistance and switched to Kaletra if their virus shows evidence of resistance, the study group said. "The longer you leave them on a failing regimen, the greater the risk that they will become resistant to all the drugs they are taking," Conradie said.

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