Pharmacokinetics, safety and efficacy of ritonavir-boosted atazanavir (300/100 mg once daily) in HIV-1-infected pregnant women.

Background: Atazanavir/ritonavir (ATV/r) is a boosted protease inhibitor recommended to minimize the risk of mother-to-child HIV-1 transmission (MTCT). We aimed to assess the pharmacokinetics, safety and efficacy of ATV/r in HIV-1-infected pregnant women and their neonates.

Methods: A multicentre, cross-sectional, non-interventional cohort of HIV-1-infected pregnant women receiving ATV/r (300/100 mg once daily) who delivered in three Paris hospitals from 2006 to 2013 was designed. We determined antiretroviral trough plasma concentrations using liquid chromatography-mass spectrometry at each of the three trimesters, delivery and post-partum. ATV concentrations at 24 h (C24h) were interpreted by the 150-850 ng/ml efficacy-tolerance thresholds. Safety data and newborn HIV status were recorded. A mother's virological failure was defined as two successive measurements of plasma HIV-1 RNA>50 copies/ml within the 2 months before delivery.

Results: 103 pregnant women were included, mostly from sub-Saharan Africa (88%). ATV C24h at each of the three trimesters and delivery remained similar to post-partum values. No dose adjustment was needed during pregnancy. The median plasma ratio of fetal/maternal ATV level was 0.19 (n=28). Only three patients showed two successive detectable viral loads but <400 copies/ml. Among 82 available newborn data, 16 were born preterm. Three in utero deaths occurred. Tolerance was good with one case of maternal grade 3 hyperbilirubinaemia, no cases in neonates at delivery and no clinically relevant adverse event. No case of MTCT was reported.

Conclusions: In this population, an ATV/r-containing antiretroviral regimen demonstrated good pharmacokinetics, virological efficacy and safety. No significant impact of pregnancy on ATV C24h was found. No dose adjustment was required.