ANP levels in breast milk during carperitide infusion

What does this LactMed case series report?

ANP levels stayed within expected range in this LactMed entry. Two lactating women received intravenous carperitide and had their breast milk ANP levels measured during and after treatment. Case 1 received 0.025 µg/kg/min and showed milk ANP of 0.31 µg/L during infusion and 0.76 µg/L afterward; Case 2 received 0.05 µg/kg/min and showed mean milk ANP of 1.68 µg/L during infusion and 1.56 µg/L afterward (ncbi.nlm.nih.gov). Neither woman's milk ANP exceeded baseline levels, indicating carperitide did not elevate ANP in milk (ncbi.nlm.nih.gov).

How low was the relative infant dose?

The case reports calculated relative infant doses on the assumption that all milk ANP came from carperitide. They reported 0.24% for the first woman and a range of 0.19%–0.53% for the second (ncbi.nlm.nih.gov). Such low percentages suggest limited infant exposure. The actual contribution of exogenous peptide remains unclear, since the assay measured total ANP and could not distinguish endogenous from exogenous sources (pubmed.ncbi.nlm.nih.gov).

What can we infer about safety and exposure?

We cannot determine safety for infants from these two cases. The trial did not report any infant outcomes, and infant plasma levels were not measured (ncbi.nlm.nih.gov). The assay could not distinguish endogenous ANP in milk from carperitide. Low breastmilk levels during infusion suggest minimal transfer, but direct infant data would be needed to resolve this uncertainty.

Why does this matter for lactation medicine?

Peptide drugs rarely have lactation data. This case series offers concrete exposure measurements when standard labeling lacks lactation-specific information. LactMed's inclusion gives clinicians and caregivers a starting point for counseling rather than silence.