Pregnant women who take the anti-HIV medication nevirapine during labor to prevent infecting their babies should wait until six months after delivery to resume taking the drug to avoid developing resistance, according to a study published in the January 11 edition of The New England Journal of Medicine. By following the findings, mothers could reduce the chance of the antiretroviral failing to work when they need it for themselves.
It translates into very clear policy for how to treat AIDS in new mothers who received nevirapine (marketed in the United States as Viramune) to protect their infants, says Harvard School of Public Health's Max Essex, an author of the study.
Once the drug is used, the risk of an infected mother developing resistance is high. In up to 69% of the women who receive a single dose of the drug the virus quickly develops resistance to it. Infants can also develop resistance in cases where the drug fails to protect them. But if the virus doesn't see nevirapine for six months after the initial dose, the drug retains its effectiveness, Essex says. Nearly 42% of the women who started receiving nevirapine within six months of giving birth developed resistance to the drug, compared to 12% who did not receive it until at least six months after delivery.