HIV drug resistance lasts about 1 year in women treated with nevirapine to prevent infant infection
15-Feb-2010- A new international study reported in PLoS Medicine confirms that a single dose of nevirapine (sdNVP)
can lead to HIV treatment failure in women who receive the drug to prevent transmission of the AIDS virus to their infants.
However, the increased risk of failure could only be detected in women who began full HIV treatment within about a year
after receiving sdNVP.
Because of its convenience and availability, sdNVP has become the mainstay for preventing mother-to-child
transmission (MTCT) of HIV in many developing country settings. However, previous studies have shown that sdNVP can induce
nevirapine-resistant HIV in treated mothers, potentially increasing the chance that subsequent HIV therapy containing
nevirapine, or other drugs of the non-nucleoside reverse transcriptase inhibitor (NNRTI) class, will fail.
In the current study, Jeffrey S.A. Stringer of the University of Alabama at the Birmingham Centre for
Infectious Disease Research in Zambia and colleagues enrolled 355 nevirapine-exposed and 523 nevirapine-unexposed women at two
sites in Zambia, one site in Kenya, and two sites in Thailand and followed them for 48 weeks after starting combination
antiretroviral therapy (ART). They found that prior exposure to sdNVP was associated with an increased risk of
subsequent ART failure, but that this risk was largely confined to women with a more recent exposure.
sdNVP-exposed women in whom this interval was more than 12 months had essentially the same
prevalence of failure at 48 weeks as women without prior exposure. The researchers
conclude that women requiring ART within 12 months of sdNVP exposure should not
be prescribed ART that includes nevirapine or efavirenz.
These findings suggest that, provided NNRTI-containing ART is not given to HIV-positive women within a year of
nevirapine exposure, single-dose nevirapine can be safely used to prevent MTCT without substantially compromising the mother's future
antiretroviral treatment options. The authors point out that liberalizing the criteria for starting full ART in pregnant women
would ensure that most women receiving sdNVP would not need ART for at least a year. In the occasional circumstance where
a woman did need therapy soon after single-dose NVP exposure, a protease inhibitor-containing regimen or a triple nucleoside regimen could be prescribed.
Funding: The Zambia work was supported by grant U62/CCU12354 from the US Centers for Disease Control and Prevention (CDC),
with complementary funding from the University of Alabama at Birmingham (UAB). The Kenya work was supported by cooperative agreement U62/CCU024526
from the US CDC. The Thailand work was supported by the US CDC through purchase orders #Bangkok-07-M-0424 to the Department of Pediatrics,
Faculty of Medicine, Siriraj Hospital, Mahidol University and #Bangkok-07-M-0425 to Rajavithi Hospital. US CDC employees were involved
in the planning, design, conduct, and interpretation of this manuscript, and in the decision to submit it for publication. The
findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the US CDC.
Competing Interests: The authors have declared that no competing interests exist.
Citation: Stringer JSA, McConnell MS, Kiarie J, Bolu O, Anekthananon T, et al. (2010) Effectiveness of Non-nucleoside
Reverse-Transcriptase Inhibitor-Based Antiretroviral Therapy in Women Previously Exposed to a Single Intrapartum Dose of Nevirapine:
A Multi-country, Prospective Cohort Study. PLoS Med 7(2): e1000233. doi:10.1371/journal.pmed.1000233
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