Safety of Tenofovir Disoproxil Fumarate Among Breastfeeding Infants of Patients With Chronic Hepatitis B: A Systematic Review

An integral component to achieving worldwide chronic hepatitis B (CHB) elimination is addressing vertical transmission. Guidelines differ in their recommendations for breastfeeding while on tenofovir disoproxil fumarate (TDF). To conduct a systematic review of published studies analysing the concentration of tenofovir (TFV) in the breast milk of mothers receiving TDF and determining infant exposure from breastfeeding. We conducted a systematic literature search of studies evaluating infant safety from the breast milk of breastfeeding mothers receiving TDF for any indication that reported a TFV breast milk concentration. Daily infant exposure was used to calculate the relative dose of TFV in infants. Other pertinent information collected was the concentration of TFV in maternal and infant plasma, the duration of therapy of TDF and the indication for TDF. We identified 10 studies including 443 patients—266 of whom were mothers, and the remaining were infants—that reported the TFV concentration of breast milk in breastfeeding mothers receiving TDF. A total of 654 breast milk samples were included. The mean TFV concentration from all the studies that reported a median concentration of TFV was 4.8 ng/mL (95% CI [3.8, 5.8]). The mean infant exposure of TFV from breast milk was 0.56 μg/kg/day (95% CI [0.44, 0.68]). The mean relative dose was determined to be 0.01% of the weight-based recommended infant dose. Infant plasma levels of TFV were also collected. This was undetectable in a majority of the studies that reported it. Based on the negligible infant exposure of TFV while breastfeeding, from a pharmacologic and toxicity standpoint, maternal dosing of TDF appears safe for breastfeeding infants.