Background At an age when breastfeeding is the optimal nutritional support for infants, enteral drug delivery can be physically and emotionally challenging for parents. Delivery during breastfeeding could serve as an alternative to currently existing approaches. This study aimed to explore its feasibility and acceptability.

Methods Vitamin B12 was administered as part of a single-centre feasibility study to breastfed infants at the University of Cambridge Addenbrooke´s Hospital NHS Trust. Hereby a solid formulation (tablet) was placed inside an ultra-thin silicone nipple shield, and worn by a mother during the feed. The study investigated i.) quantitative changes in B12 blood serum levels at baseline and 6–8 hours after the study feed, ii.) mothers’ expectations and experiences via a mixed method approach by a single investigator. Local ethics approval was obtained prior to any study procedures being undertaken (18/LO/0551).

Results Twenty dyads completed the study protocol. In all cases, no residual tablet was left after the feed, and the tablet’s presence within the shield did not appear to impact feeding. A pharmacokinetic-dependent vitamin B12 increase to 1871 pg/mL (610–4981 pg/mL) from a baseline of 533 pg/mL (236–925 pg/mL) was observed. Mothers described the nipple shield´s surprising ease of use and comfort for delivery, not affecting normal breastfeeding behaviour/sensation, while decreasing infant/maternal distress compared to the use of an oral syringe. All mothers expressed their wish for this approach to become available to parents in the future. Reasoning included the desire (1) of parents to have choices in relation to their infants’ health, (2) to replace a medical intervention with one that was felt to be more ‘natural’.

Conclusions This study showed that solid formulations can be used for therapeutic delivery whilst breastfeeding and is viewed by mothers as advantageous compared to currently available methods.

Funding The research was supported by a WD Armstrong PhD studentship for the Application of Engineering in Medicine, University of Cambridge, the German Academic Scholarship Foundation, and the Kurt Hahn Trust, University of Cambridge. Competing interests (applicable to all authors): None declared.