Lack of Effect from a Previous Single Dose of Nevirapine on Virologic and Immunologic Responses After 6 Months of Antiretroviral Regimens Containing Either Efavirenz or Lopinavir-Ritonavir

Study Objective. To evaluate the effect of a previous single dose of nevirapine given to prevent mother-to-child transmission of human immunodeficiency virus (HIV) on virologic and immunologic measures after 6 months of an antiretroviral regimen containing either efavirenz or lopinavir-ritonavir. Design. Retrospective subgroup analysis of data from the Phidisa II trial. Setting. Six South African research clinics. Patients. A total of 394 women with HIV who completed 6 months of combination antiretroviral regimen containing either efavirenz or lopinavir-ritonavir as part of the Phidisa II trial. Measurements and Main Results. During the screening process for the Phidisa II study, 478 women were asked about previous nevirapine use: 392 women (82%) were nevirapine naive, and 86 (18%) had received nevirapine. During the study, patients received either an efavirenz-based or lopinavir-ritonavir based antiretroviral regimen. After 6 months of treatment, virologic (HIV RNA levels) and immunologic (CD4(+) cell count) responses were measured. These data were compared between women with or without previous nevirapine exposure, and between women who received efavirenz versus lopinavir-ritonavir. After 6 months of treatment, 394 women (324 nevirapine naive, 70 exposed to nevirapine) had follow-up HIV RNA results. Two hundred twenty-seven (70.1%) of the nevirapine-naive patients and 48 (68.6%) of the nevirapine-exposed patients achieved HIV RNA levels lower than 400 copies/ml (p=0.89), with CD4(+) cell count increases of 115.5 and 120.4 cells/mm(3), respectively (p=0.67). Among the nevirapine-exposed women, 27 (75%) of 36 efavirenz-treated and 21 (61.8%) of 34 lopinavir-ritonavir-treated patients had HIV RNA levels lower than 400 copies/ml at 6 months (p=0.31). Conclusion. In this retrospective analysis of a small cohort, previous exposure to a single dose of nevirapine did not affect virologic outcomes after 6 months of either an efavirenz-based or lopinavir-ritonavir-based antiretroviral regimen. As efavirenz is one of the first-line combination antiretroviral therapies administered in Africa, it remains an option for women who received single-dose nevirapine.

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