Pre-exposure Prophylaxis Use by Breastfeeding HIV-Uninfected Women: A Prospective Short-Term Study of Antiretroviral Excretion in Breast Milk and Infant Absorption

BackgroundAs pre-exposure prophylaxis (PrEP) becomes more widely used in heterosexual populations, an important consideration is its safety in infants who are breastfed by women taking PrEP. We investigated whether tenofovir and emtricitabine are excreted into breast milk and then absorbed by the breastfeeding infant in clinically significant concentrations when used as PrEP by lactating women.Methods and FindingsWe conducted a prospective short-term, open-label study of daily oral emtricitabine–tenofovir disoproxil fumarate PrEP among 50 HIV-uninfected breastfeeding African mother–infant pairs between 1–24 wk postpartum (ClinicalTrials.gov Identifier: NCT02776748). The primary goal was to quantify the steady-state concentrations of tenofovir and emtricitabine in infant plasma ingested via breastfeeding. PrEP was administered to women through daily directly observed therapy (DOT) for ten consecutive days and then discontinued thereafter. Non-fasting peak and trough samples of maternal plasma and breast milk were obtained at drug concentration steady states on days 7 and 10, and a single infant plasma sample was obtained on day 7. Peak blood and breast milk samples were obtained 1–2 h after the maternal DOT PrEP dose, while maternal trough samples were obtained at the end of the PrEP dosing interval (i.e., 23 to 24 h) after maternal DOT PrEP dose. Tenofovir and emtricitabine concentrations were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays.Of the 50 mother–infant pairs enrolled, 48% were ≤12 wk and 52% were 13–24 wk postpartum, and median maternal age was 25 y (interquartile range [IQR] 22–28). During study follow-up, the median (IQR) daily reported frequency of infant breastfeeding was 15 times (12 to 18) overall, 16 (14 to 19) for the ≤12 weeks, and 14 (12 to 17) for the 13–24 wk infant age groups. Overall, median (IQR) time-averaged peak concentrations in breast milk were 3.2 ng/mL (2.3 to 4.7) for tenofovir and 212.5 ng/mL (140.0 to 405.0) for emtricitabine. Similarly, median (IQR) time-averaged trough concentrations in breast milk were 3.3 ng/mL (2.3 to 4.4) for tenofovir and 183.0 ng/mL (113.0 to 250.0) for emtricitabine, reflecting trough-to-peak breast milk concentration ratios of 1.0 for tenofovir and 0.8 for emtricitabine, respectively. In infant plasma, tenofovir was unquantifiable in 46/49 samples (94%), but emtricitabine was detectable in 47/49 (96%) (median [IQR] concentration: 13.2 ng/mL [9.3 to 16.7]). The estimated equivalent doses an infant would ingest daily from breastfeeding were 0.47 μg/kg (IQR 0.35 to 0.71) for tenofovir and 31.9 μg/kg (IQR 21.0 to 60.8) for emtricitabine, translating into a The key study limitation was that only a single infant sample was collected to minimize venipunctures for the children. However, maternal daily DOT and specimen collection at drug concentration steady state provided an adequate approach to address the key research question. Importantly, there was minimal variation in breast milk concentrations of tenofovir and emtricitabine (respective median trough-to-peak concentration ratio ~1), demonstrating that infants were exposed to consistent drug dosing via breast milk.ConclusionIn this short-term study of daily directly observed oral PrEP in HIV-uninfected breastfeeding women, the estimated infant doses from breast milk and resultant infant plasma concentrations for tenofovir and emtricitabine were 12,500 and >200-fold lower than the respective proposed infant therapeutic doses, and tenofovir was not detected in 94% of infant plasma samples. These data suggest that PrEP can be safely used during breastfeeding with minimal infant drug exposure.Trial RegistrationClinicalTrials.gov, Identifier: NCT02776748

背景 随着暴露前预防（pre-exposure prophylaxis, PrEP）在异性恋人群中的应用日益广泛，服用PrEP的哺乳期女性所母乳喂养的婴儿的安全性成为一项重要考量。本研究旨在探讨哺乳期女性使用PrEP时，替诺福韦（tenofovir）与恩曲他滨（emtricitabine）是否会排入母乳，并以具有临床意义的浓度被母乳喂养婴儿吸收。

方法与结果 本研究针对产后1~24周的50对HIV未感染的非洲哺乳期母婴对，开展了一项前瞻性短期开放标签研究，评估每日口服恩曲他滨-富马酸替诺福韦二吡呋酯PrEP的方案（ClinicalTrials.gov标识符：NCT02776748）。本研究的主要目标是量化婴儿经母乳喂养摄入的替诺福韦与恩曲他滨的稳态血浆浓度。研究对象连续10日每日接受直接面视下服药（directly observed therapy, DOT）的PrEP给药，随后停止用药。在第7日和第10日的药物稳态浓度阶段，采集产妇血浆与母乳的非空腹峰浓度与谷浓度样本；并于第7日采集单份婴儿血浆样本。产妇在接受DOT PrEP给药后1~2小时采集峰浓度血液与母乳样本，谷浓度样本则于给药间隔期末（即给药后23~24小时）采集。采用液相色谱-串联质谱法（liquid chromatography-tandem mass spectrometry, LC-MS/MS）对替诺福韦与恩曲他滨的浓度进行定量检测。

入组的50对母婴对中，48%的婴儿产后时长≤12周，52%为13~24周；产妇的中位年龄为25岁（四分位距[IQR] 22~28）。研究随访期间，整体婴儿母乳喂养的中位（IQR）每日频次为15次（12~18次）；其中≤12周龄组为16次（14~19次），13~24周龄组为14次（12~17次）。整体而言，母乳中替诺福韦的时间平均峰浓度中位数（IQR）为3.2 ng/mL（2.3~4.7），恩曲他滨为212.5 ng/mL（140.0~405.0）。类似地，母乳中替诺福韦的时间平均谷浓度中位数（IQR）为3.3 ng/mL（2.3~4.4），恩曲他滨为183.0 ng/mL（113.0~250.0），二者的母乳谷峰浓度比分别为1.0与0.8。在婴儿血浆中，49份样本中有46份（94%）未检出替诺福韦，但47份（96%）可检出恩曲他滨，其浓度中位数（IQR）为13.2 ng/mL（9.3~16.7）。经估算，婴儿每日经母乳喂养摄入的等效剂量为：替诺福韦0.47 μg/kg（IQR 0.35~0.71），恩曲他滨31.9 μg/kg（IQR 21.0~60.8）。本研究的关键局限性在于，仅采集单份婴儿样本以尽量减少幼儿的静脉穿刺操作。不过，产妇每日接受DOT给药以及在药物稳态浓度阶段采集样本的方案，能够充分解决核心研究问题。值得注意的是，母乳中替诺福韦与恩曲他滨的浓度波动极小（二者的中位谷峰浓度比均约为1），表明婴儿经母乳接触的药物剂量保持一致。

结论 在这项针对HIV未感染哺乳期女性的每日直接面视下口服PrEP短期研究中，经估算，婴儿从母乳中摄入的替诺福韦与恩曲他滨剂量，以及由此产生的婴儿血浆浓度，分别较推荐的婴儿治疗剂量低12500倍与200倍以上；且94%的婴儿血浆样本中未检出替诺福韦。上述数据表明，哺乳期使用PrEP具有安全性，婴儿暴露的药物剂量极低。

试验注册 ClinicalTrials.gov，标识符：NCT02776748