Maternal-fetal transfer and amniotic fluid accumulation of lamivudine in human immunodeficiency virus-infected pregnant women

OBJECTIVE: The purpose of this study was to investigate placental transfer and amniotic fluid concentrations of lamivudine in human immunodeficiency v irus-infected women who received the agent during pregnancy. STUDY DESIGN: Mothers in the study were receiving antiretroviral therapy th at included lamivudine in a clinical setting. Maternal blood, cord blood, a nd amniotic fluid samples were obtained simultaneously at the time of deliv ery from 57 mother-infant pairs. RESULTS: At a median of 8.5 hours after the last maternal oral 150-mg dose of lamivudine, median maternal and fetal plasma concentrations were 302 and 240 ng/mL, respectively. Individual maternal and fetal concentrations were strongly correlated (r(2) = 0.36; P < 10(-4)), and their median ratio was about 1. The median concentration in the amniotic fluid was 5 times higher than that in maternal plasma (upper range of ratio, 133). CONCLUSION: Lamivudine appeared to cross the placenta by simple diffusion a nd is concentrated in the amniotic fluid. High amniotic fluid levels of lam ivudine may carry both benefits and risks for the child.