Lactation Safety
Assessment of whether a drug is safe to use during breastfeeding, considering transfer into breast milk and potential effects on the nursing infant. Peptide drugs are generally expected to be degraded in the infant's gastrointestinal tract if ingested, but individual risk assessments are required.
Technical Context
Factors affecting breast milk drug transfer: molecular weight (peptides >1000 Da generally transfer poorly), protein binding (highly albumin-bound peptides transfer less), lipophilicity (hydrophilic peptides transfer less), half-life, and maternal plasma levels. Relative infant dose (RID) = (infant dose via milk / maternal dose) × 100; RID <10% is generally considered compatible with breastfeeding. For peptide drugs, even if small amounts transfer into milk, degradation in the infant's GI tract would be expected to inactivate most peptides (the same GI proteases that prevent oral bioavailability in adults). However, clinical data on breastfeeding safety of peptide drugs are limited because nursing women are typically excluded from clinical trials. Individual risk-benefit assessment considers: medical necessity of the drug, infant age and health, availability of alternatives, and the specific peptide's physicochemical properties.