Tirzepatide

How does tirzepatide work?

Tirzepatide is a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist, meaning it activates two gut-hormone receptor pathways rather than one [1]. Both Zepbound and Mounjaro are given as once-weekly subcutaneous injections, starting at 2.5 mg and titrated in 2.5 mg increments to a maximum of 15 mg in adults [1][2]. Coadministration with any other GLP-1 receptor agonist or another tirzepatide-containing product is not recommended [2].

What is the difference between Zepbound and Mounjaro?

Zepbound is FDA-approved for chronic weight management and moderate to severe obstructive sleep apnea in adults with obesity [2]. Mounjaro is FDA-approved to improve glycemic control in adults and children 10 and older with type 2 diabetes; chronic weight management is not an approved Mounjaro indication [1].

What are the risks of tirzepatide?

Both brands carry a boxed warning: in rats, tirzepatide causes thyroid C-cell tumors, and it is unknown whether it causes thyroid C-cell tumors, including medullary thyroid carcinoma, in humans [1][2]. Tirzepatide is contraindicated in patients with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 [1][2]. The most commonly reported side effects include nausea, diarrhea, vomiting, and constipation [2].