Tirzepatide

This review-style report examines the transfer of tirzepatide, a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist, into human breastmilk following subcutaneous administration. The paper notes that tirzepatide is generally undetectable in breastmilk at doses up to 5 mg, suggesting minimal maternal-to-infant transfer via lactation. The authors further reason that even if trace amounts were present, oral absorption by a nursing infant would likely be negligible, as the peptide is expected to undergo partial degradation in the infant's gastrointestinal tract and exhibits poor oral bioavailability. Based on these considerations, the paper concludes that maternal use of tirzepatide need not be an automatic reason to discontinue breastfeeding, while still recommending caution — particularly in the context of newborns or preterm infants, whose gastrointestinal and metabolic systems may differ from those of older infants. The report acknowledges that available data remain limited and calls for additional research before stronger conclusions can be drawn. Key limitations include the small body of evidence underpinning these conclusions and the absence of robust clinical trial data in lactating populations.

Why this grade: The paper is a narrative review or drug monograph summarizing limited observational or pharmacokinetic data in lactating humans, without a controlled trial design or large sample population, yielding only limited human evidence.