Drug Transfer and Exposure in Human Milk

Drug transfer into human milk represents a critical intersection between maternal pharmacotherapy and neonatal safety. Following maternal ingestion, drugs distribute into systemic circulation and may partition into breast milk according to their physicochemical properties, binding affinities and the dynamic physiology of the mammary gland. Key determinants include molecular size, lipophilicity, ionisation at physiological pH and plasma protein binding, which together influence the milk‐to‐plasma concentration ratio. Once in milk, compounds can reach the nursing infant at variable doses, potentially eliciting pharmacological effects or adverse reactions. Monitoring exposure is further complicated by fluctuations in milk composition, feeding frequency and infant metabolism. Research has increasingly focused on bridging experimental, modelling and real‐world surveillance approaches to quantify exposure and guide safe maternal medication. Advances in physiologically based pharmacokinetic modelling and high‐throughput analytical methods now enable more precise prediction of milk concentrations and infant doses, while pharmacovigilance databases offer insight into reported outcomes. This integrated framework supports evidence-driven guidance for clinicians and informs risk–benefit decisions in lactation pharmacotherapy worldwide.

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Drug Transfer and Exposure in Human Milk publication trend

The graph below shows the total number of articles in drug transfer and exposure in human milk across all publications each year (not limited to Nature Index journals).

Technical terms

Pharmacokinetics: The study of how a drug is absorbed, distributed, metabolised and eliminated in the body.

Physiologically based pharmacokinetic (PBPK) modelling: A mathematical modelling approach that simulates drug kinetics using detailed physiological and biochemical parameters of specific populations.

Milk-to-plasma ratio: The concentration of drug in breast milk divided by its concentration in maternal plasma, indicating extent of transfer.

Relative infant dose: The estimated daily infant drug intake via milk expressed as a percentage of the maternal weight-adjusted dose.

References

1. Generic Workflow to Predict Medicine Concentrations in Human Milk Using Physiologically-Based Pharmacokinetic (PBPK) Modelling—A Contribution from the ConcePTION Project. Pharmaceutics (2023).
2. Drug Safety During Breastfeeding: A Comparative Analysis of FDA Adverse Event Reports and LactMed®. Pharmaceuticals (2024).
3. A systematic review on maternal-to-infant transfer of drugs through breast milk during the treatment of malaria, tuberculosis, and neglected tropical diseases. PLOS Neglected Tropical Diseases (2023).