Zambia: New Drug Combo Eases Mother-Infant HIV Dilemma
December 10, 2007
A study of HIV-infected pregnant women given a new drug combination of non-nucleoside reverse transcriptase inhibitors (NNRTIs) during labor found they were about half as likely to develop resistance to that class of drugs six weeks after delivery as a second group given fewer AIDS drugs.
A single dose of the NNRTI nevirapine during labor reduces a mother's chance of infecting her infant by 40 percent. But if the newborn does become infected, the baby is far more likely to acquire a strain of the virus that is resistant to common HIV drugs. There is also an increased chance the same resistant virus will develop in the already infected mother.
Benjamin Chi of the Center for Infectious Disease Research and the University of Alabama-Birmingham and colleagues studied 397 HIV-infected pregnant women seeking care at two public health facilities in Lusaka, Zambia. About half (199) of the mothers-to-be were given single doses of tenofovir and emtricitabine, both NNRTIs, along with nevirapine during birth. The second group (198) was given nevirapine, as is the standard practice. Both groups also took a short course of zidovudine (AZT).
The researchers determined that six weeks post-delivery, the women given the four-drug combination were 53 percent less likely to develop higher resistance to NNRTIs. The absolute risk was cut in half: 12 percent for the test group, and 25 percent for the control group.
Some serious adverse events were reported -- postpartum anemia for mothers, pneumonia for the infants -- in both groups, though none was judged to be caused by the four-drug combo.
The study's results "provide strong evidence that adding single-dose tenofovir/emtricitabine" to the standard treatment "is a new, effective, and feasible approach to reducing maternal nevirapine resistance," Shahin Lockman and James McIntyre of the Harvard School of Public Health said in a related commentary.
The study, "Single-Dose Tenofovir and Emtricitabine for Reduction of Viral Resistance to Non-Nucleoside Reverse Transcriptase Inhibitor Drugs in Women Given Intrapartum Nevirapine for Perinatal HIV Prevention: An Open-Label Randomized Trial," and the commentary, "Reduction of HIV-1 Drug Resistance After Intrapartum Single-Dose Nevirapine," were published in The Lancet (2007;370(9600):1698-1705 and 1668-1670, respectively).
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