Tirzepatide is a long-acting GIP (glucose-dependent insulinotropic polypeptide) receptor and GLP-1 (glucagon-like peptide-1) receptor agonist that increases insulin sensitivity and secretion, suppresses glucagon secretion, and slows gastric emptying.
Tirzepatide is used to treat Type 2 diabetes mellitus as monotherapy (if metformin is inappropriate), or in combination with other antidiabetic drugs (including insulin) if existing treatment fails to achieve adequate glycaemic control. It is also used in the treatment of obesity by weekly subcutaneous administration.
No information is available on the clinical use of tirzepatide during breastfeeding. Because tirzepatide is a large peptide molecule with a molecular weight of 4814 Da, the amount in milk is likely to be low and absorption is unlikely because it is probably partially destroyed in the infant’s gastrointestinal tract. Until more data become available, tirzepatide should be used with caution during breastfeeding, especially while nursing a newborn or preterm infant. (LactMed).
Due to its protein nature, it is inactivated in the gastrointestinal tract and is not absorbed (oral bioavailability is practically nil), which makes it difficult or impossible for it to pass into the infant’s plasma from ingested breast milk, except in premature infants and in the immediate neonatal period, where there may be greater intestinal permeability. (E-lactancia).
While caution is still necessary without confirmatory data, it is unlikely to be present in large quantities in the milk compartment (Hale )
See also https://www.infantrisk.com/content/weight-loss-lactation
https://www.springerpub.com/blog/weight-loss-drugs-breastfeeding
Hale and Krutsch (Infantrisk pharmacists express concern on the use of weight loss medications and breastfeeding due to inadequate consumption of nutrients.
“Concerns have been expressed about how the pharmacodynamics of GLP-1 agonists such as tirzepatide or semaglutide could impact the nutritional constituents of milk. These drugs are analogs of natural GLP-1 with small modifications to slow their degradation by the DPP-4 enzyme. However, lactation, in general, is expected to occur during a catabolic physiological state – GLP-1 agonists catalyze the catabolism to encourage weight loss. As long as the mother has sufficient weight to lose, the nutrient profile of milk would likely be similar if compared to a diet producing equivalent weight loss. If a mother is reducing caloric intake for any reason, we recommend a postnatal vitamin and attention to consuming enough calories to meet the elevated nutrient needs required during lactation”.
Other sources of information
NICE TA 1026 Tirzepatide for managing overweight and obesity . https://www.nice.org.uk/guidance/ta1026
See also Semaglutide and Breastfeeding https://breastfeeding-and-medication.co.uk/fact-sheet/semaglutide-and-breastfeeding
Liraglutide and Breastfeeding https://breastfeeding-and-medication.co.uk/fact-sheet/liraglutide-saxenda-and-breastfeeding
