Spotlight on a New Peptide Approval, Tirzepatide

First published: May 25, 2022

As our focus at AmbioPharm is on peptides, it is always exciting to see a new peptide drug approval.  Recently, Eli Lilly received an approval by the FDA for tirzepatide (Mounjaro™) for the treatment of adults with type II diabetes (T2D).

Type II diabetes is a condition where the body produces insulin at insufficient levels.  Incretin hormones, or gut peptides, play a role in insulin secretion called the incretin effect.   Of these incretins, glucose-dependent insulinotropic polypeptide (GIP) is found in the upper gut, while glucagon-like peptide 1 (GLP-1) is found in the lower gut.  Several glucagon-like peptide 1 (GLP-1) receptor agonists, or GLP-1Ras, have already been developed and approved for the treatment of type-2 diabetes (such as exenatide, lixisenatide, liraglutide, and semaglutide) via subcutaneous injection. An agonist binds to a receptor protein triggering a biological response and these receptor agonists function by stimulating the production of insulin in the patient following administration.  Meanwhile, incretins are metabolized by dipeptidyl peptidase 4 (DPP-4) and overcoming DPP-4 degradation can be a challenge that scientists have had to overcome. Another strategy in avoiding degradation is adding a DPP-4 inhibitor alongside a GLP-1RA.1

What makes tirzepatide unique is that it is one molecule that is both a GIP and a GLP-1 receptor agonist, or a dual agonist.2 

Update (Oct 6, 2022): Eli Lilly receives U.S. FDA Fast Track designation for tirzepatide for the treatment of adults with obesity and plans a rolling submission of a new drug application (NDA). It is currently in Phase III clinical trials for this indication.3


  1. Nauck MA, Meier JJ. Incretin hormones: Their role in health and disease. Diabetes Obes Metab. 2018 Feb; 20 Suppl 1:5-21. doi: 10.1111/dom.13129. PMID: 29364588. Retrieved May 2022:
  2. FDA approves Lilly’s Mounjaro™ (tirzepatide) injection, the first and only GIP and GLP-1 receptor agonist for the treatment of adults with type 2 diabetes.
  3. Lilly receives U.S. FDA Fast Track designation for tirzepatide for the treatment of adults with obesity, or overweight with weight-related comorbidities.

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