Kinetics of Nevirapine and Its Impact on HIV-1 RNA Levels in Maternal Plasma and Breast Milk Over Time After Perinatal Single-Dose Nevirapine

Objective: To determine kinetics after single-dose nevirapine and the impact on HIV RNA [viral load (VL)] in maternal plasma and breast milk (BM). Methods: Cohort of 120 HIV-1-infected pregnant Ugandan women received perinatal single-dose nevirapine alone and followed up with their infants through 24 weeks postdelivery. We assessed the relationship of nevirapine concentration (tandem mass spectroscopy) and HIV-1 VL (Roche AMPLICOR HIV-1 Kit, version 1.5) in maternal plasma and BM over time. Results: At week 1 postpartum, NVP (>= 10 ng/mL) was detected in all 53 plasma and 47 of 51 (92.2%) BM samples with median (interquartile ranges) of, respectively, 171 (78-214) ng/mL and 112 (64-158) ng/mL, P = 0.075, which decreased subsequently with traces persisting through week 4 in plasma. Plasma and BM VL dropped by week 1 and were highly correlated at delivery (R = 0.71, P < 0.001) and week 1 (R = 0.69, P < 0.001) but not thereafter. At week 1, VL correlated inversely with NVP concentration in plasma (R = 0.39, P = 0.004) and BM (R = 0.48, P = 0.013). There was a VL rebound in both compartments, which peaked at week 4 to levels greater than those at week 1 [significantly in plasma (P < 0.001) but not in BM] and remained stable thereafter. Median VL was consistently greater (11- to 50-fold) in plasma than BM at all time points (all P < 0.001). Conclusions: After single-dose nevirapine, NVP concentration was comparably high through week 1, accompanied by suppression of plasma and BM VL. A longer tail (>1 week) of potent postnatal antiretroviral drugs is warranted to minimize the observed VL rebound and potential for NVP resistance as a result of persistent NVP traces.