A single dose of tenofovir and emtricitabine can reduce resistance.

A single dose of tenofovir and emtricitabine at delivery reduced resistance to nonnucleoside reverse transcriptase inhibitors at 6 weeks after delivery by half.

Intrapartum and neonatal single-dose nevirapine are commonly used and essential in the prevention of mother-to-child transmission of HIV in resource-poor settings, but may induce resistance to other non-nucleoside reverse transcriptase inhibitors.

The aim of this study carried out by Benjamin Chi and colleagues in Lusaka, Zambia, was to see if this complication could be reduced by the introduction of a single peripartum dose of tenofovir and emtricitabine.

They randomly assigned 400 pregnant women who came to two public sector primary health care clinics in Lusaka. They assigned 200 of the women to receive a single oral dose of 300 mg tenofovir with 200 mg emtricitabine under direct observation, and 199 to receive no study drug. Short-course zidovudine and intrapartum nevirapine were offered to all HIV-infected women, according to the local standard of care. Those women who were eligible to receive antiretroviral therapy according to local national guidelines were not enrolled in the study.

Women given the intervention were 53% less likely than controls to have a mutation that conferred resistance to nonnucleoside reverse transcriptase inhibitors at 6 weeks after delivery.

The authors recommend that this treatment should be offered as an adjuvant to intrapartum nevirapine.

Chi B, et al. Lancet 2007; early online publication. DOI:10.1016/S0140-6736(07)61605-5