Therapeutic Options for Women Exposed to Nevirapine

Single-dose nevirapine (sd-NVP) is a simple and effective intervention to prevent mother-to-child HIV transmission (PMTCT) in low resource settings. Unfortunately, several studies have observed evidence of drug resistance to nevirapine among HIV-infected women soon after sd-NVP for PMTCT. If this “resistance” persists long-term and has adverse clinical consequences, then treatment options for women may be curtailed. Nevirapine and other drugs in the same class are an important part of therapeutic antiretroviral drug regimens. In our study, we propose to investigate whether allowing a longer time since exposure to sd-NVP to elapse can reduce any subsequent consequences on a woman's response to a treatment regimen that contains nevirapine. We hypothesize that if more than 18 months has elapsed since sd-NVP then there will be no adverse effect on a woman's response to therapy. However if therapy is started sooner, then some sd-NVP-exposed women may not suppress virus as easily as women who have never previously been exposed to nevirapine when they are started on a nevirapine-containing regimen. We will investigate this question in the context of a study of HIV-infected women at two clinics in Lusaka, Zambia, who received sd-NVP for PMTCT and who now have access to antiretroviral treatment through the government of Zambia and President's Emergency Plan for AIDS Relief HIV care and treatment programs. If we could identify a length of time after exposure to sd-NVP that no longer conveys any measurable impact on response to therapy, then we could significantly reduce the numbers of women whose treatment options would need to be limited. As HIV treatment programs are put in place, sicker women should be placed on treatment before and during pregnancy leaving few HIV-positive women who will need drug treatment soon after delivery.