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



We 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 <0.01% and 0.5% relative dose when compared to the 6 mg/kg dose that is proposed for therapeutic treatment of infant HIV infection and for prevention of infant postnatal HIV infection; a dose that has not shown safety concerns. No serious adverse effects were recorded during study follow-up. 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.



In 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.



ClinicalTrials.gov, Identifier: NCT02776748.
Department of Epidemiology, University of Washington, Seattle, Washington, United States of America.|Department of Global Health, University of Washington, Seattle, Washington, United States of America.|Division of Disease Control, School of Public Health, Makerere University, Kampala, Uganda.
Kenneth K
0000-0001-5208-7468
KK
Mugwanya
Department of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America.
Craig W
CW
Hendrix
Department of Global Health, University of Washington, Seattle, Washington, United States of America.|Kenya Medical Research Institute, Nairobi, Kenya.
Nelly R
NR
Mugo
Department of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America.
Mark
M
Marzinke
Department of Medicine, Makerere University, Kampala, Uganda.
Elly T
ET
Katabira
Department of Global Health, University of Washington, Seattle, Washington, United States of America.|Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
Kenneth
K
Ngure
Infectious Diseases Institute, Makerere University, Kampala, Uganda.
Nulu B
NB
Semiyaga
Department of Epidemiology, University of Washington, Seattle, Washington, United States of America.|Department of Global Health, University of Washington, Seattle, Washington, United States of America.|Department of Medicine, University of Washington, Seattle, Washington, United States of America.|Department of Pediatrics, University of Washington, Seattle, Washington, United States of America.
Grace
G
John-Stewart
Infectious Diseases Institute, Makerere University, Kampala, Uganda.
Timothy R
0000-0002-8478-9234
TR
Muwonge
Partners in Health Research and Development, Thika, Kenya.
Gabriel
0000-0003-2243-9789
G
Muthuri
Department of Global Health, University of Washington, Seattle, Washington, United States of America.|Department of Pharmacy, University of Washington, Seattle, Washington, United States of America.
Andy
A
Stergachis
Department of Epidemiology, University of Washington, Seattle, Washington, United States of America.|Department of Global Health, University of Washington, Seattle, Washington, United States of America.|Department of Medicine, University of Washington, Seattle, Washington, United States of America.
Connie L
CL
Celum
Department of Epidemiology, University of Washington, Seattle, Washington, United States of America.|Department of Global Health, University of Washington, Seattle, Washington, United States of America.|Department of Medicine, University of Washington, Seattle, Washington, United States of America.
Jared M
JM
Baeten
D000284:Administration, Oral; D019380:Anti-HIV Agents / Q000493:pharmacokinetics*; D001942:Breast Feeding / Q000009:adverse effects; D000068679:Emtricitabine / Q000493:pharmacokinetics*; D005260:Female; D015658:HIV Infections / Q000517:prevention & control*; D006801:Humans; D007774:Lactation; D008895:Milk, Human / Q000737:chemistry*; D065129:Pre-Exposure Prophylaxis / Q000379:methods*; D011446:Prospective Studies; D000068698:Tenofovir / Q000493:pharmacokinetics*
D019380:Anti-HIV Agents; D000068698:Tenofovir; D000068679:Emtricitabine
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