A 39-amino-acid dual agonist of the GIP and GLP-1 receptors (CAS 2023788-19-2), built on the GIP sequence with a C20 fatty diacid that binds albumin and prolongs its half-life. It enhances glucose-dependent insulin secretion and lowers glucagon, and nonclinical studies suggest the GIP component adds to GLP-1's regulation of food intake. FDA-approved by Eli Lilly as Mounjaro (type 2 diabetes) and Zepbound (chronic weight management and obstructive sleep apnea in adults with obesity).
Tirzepatide (Eli Lilly's LY3298176) is a 39-amino-acid synthetic peptide that activates two receptors at once: the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor. It is built on a GIP peptide backbone modified with a C20 fatty-diacid chain that binds albumin and extends the molecule's half-life.
The dual mechanism is what distinguishes tirzepatide from single-target GLP-1 drugs such as semaglutide. GLP-1 receptor activation slows gastric emptying and increases satiety, reducing food intake. Nonclinical studies suggest the added GIP-receptor activity may further contribute to the regulation of food intake. Retatrutide adds a third receptor (glucagon) on top of the same two targets.
Phase 3 trial results
Tirzepatide's efficacy was established in two large Phase 3 programs sponsored by Eli Lilly: SURPASS in type 2 diabetes and SURMOUNT in obesity.
In SURMOUNT-1 (New England Journal of Medicine, 2022), adults with obesity or overweight without diabetes received tirzepatide for 72 weeks. Mean body-weight reductions were 16.0%, 21.4%, and 22.5% across the three doses tested, from lowest to highest, versus 2.4% for placebo, in the analysis that assumes participants stayed on treatment.
In SURPASS-2 (New England Journal of Medicine, 2021), a head-to-head trial in type 2 diabetes, tirzepatide produced greater reductions in A1C and body weight than injectable semaglutide at a type 2 diabetes dose over 40 weeks. A later head-to-head obesity trial, SURMOUNT-5 (2025), reported a mean weight reduction of 20.2% for tirzepatide versus 13.7% for semaglutide at 72 weeks, counting participants who stopped treatment. Retatrutide vs tirzepatide vs semaglutide covers how that direct comparison differs from comparing separate trials.
FDA approval timeline
Tirzepatide is FDA-approved and commercially available under two Eli Lilly brand names. Mounjaro was approved in May 2022 for glycemic control in adults with type 2 diabetes. Its label added pediatric patients 10 years and older in December 2025, and in August 2026 an indication to reduce the risk of major adverse cardiovascular events in adults with type 2 diabetes at high cardiovascular risk. Zepbound was approved in November 2023 for chronic weight management in adults with obesity, or with overweight and at least one weight-related comorbid condition. In December 2024 its label was expanded to include moderate-to-severe obstructive sleep apnea in adults with obesity, based on the SURMOUNT-OSA trial.
Because tirzepatide is an approved drug, the branded product is dispensed by prescription through licensed U.S. pharmacies. As a component of FDA-approved drugs, tirzepatide also sits outside the 503A bulks-list review that decides compounding eligibility for many unapproved research peptides. What the tirzepatide exclusion order covers explains the scope of the U.S. International Trade Commission's April 2025 order on tirzepatide imports.
Vendor naming conventions
Research vendors often list tirzepatide under a code rather than its generic name. A common convention is generational "GLP-N" branding, in which GLP1 refers to semaglutide, GLP2 to tirzepatide, and GLP3 to retatrutide. This is a commercial release-order scheme, separate from the scientific receptor nomenclature. (Tirzepatide is a GLP-1/GIP dual agonist, not a "GLP-2" analog. The actual GLP-2 analog, teduglutide, is an unrelated drug.) Common tirzepatide codes include GLP2-T, T-GLP2, TRZ, TZ-2, and EZP-2P, and numeric suffixes such as T-10 and T-30 typically encode the vial size in milligrams. Our post on what GLP-3 means walks through the whole GLP-1, GLP-2 and GLP-3 code series.
Because a vendor can instead use the literal scientific convention (where "GLP2" means teduglutide), PeptideScouter verifies every listing against its published CAS or molecular formula (C225H348N48O68, CAS 2023788-19-2) before mapping it, rather than trusting the product name. All known vendor codes are normalized back to the canonical peptide so prices can be compared per milligram across vendors.
Frequently asked questions
Is tirzepatide the same as Mounjaro and Zepbound?
Yes. Mounjaro and Zepbound are both Eli Lilly brand names for the same molecule, tirzepatide. Mounjaro was approved in 2022 for type 2 diabetes, while Zepbound was approved in 2023 for chronic weight management and in 2024 for obstructive sleep apnea in adults with obesity. The differences are the approved indication and labeling, not the active compound.
How is tirzepatide different from semaglutide and retatrutide?
Semaglutide activates one receptor (GLP-1), tirzepatide activates two (GLP-1 and GIP), and retatrutide activates three (GLP-1, GIP, and glucagon). The comparison is mechanistic, and PeptideScouter does not make claims about which compound is better for any individual.
Why do vendors sell tirzepatide as "GLP2"?
"GLP-N" is an informal generational branding code used across many peptide vendors: GLP1 typically means semaglutide, GLP2 tirzepatide, and GLP3 retatrutide, reflecting drug generation rather than scientific receptor class. Numeric suffixes such as T-10 or T-30 usually encode vial size in milligrams. Because the naming is inconsistent between vendors, every listing is verified by CAS or molecular formula before being mapped to tirzepatide.
Is tirzepatide FDA approved?
The molecule is FDA-approved as the prescription drugs Mounjaro and Zepbound. However, the material sold by research peptide vendors is research-grade and is offered for laboratory research use only, not as the FDA-approved pharmaceutical product and not for human consumption.
Where can I buy Tirzepatide online?
Tirzepatide is sold by 46 research peptide vendors indexed on PeptideScouter, with 249 tracked listings compared per vendor in the table above. Pricing is normalized and refreshed daily.
Is Tirzepatide in stock right now?
All 46 indexed research peptide vendors currently have Tirzepatide in stock. Stock state is refreshed daily from each vendor's catalog.
What is the cheapest place to buy Tirzepatide?
Studz Peptides currently lists Tirzepatide at $0.97/mg, the lowest listed price across 46 tracked research peptide vendors. With current vendor discount codes applied, the lowest effective price is $0.75/mg.
Is there a discount code for Tirzepatide?
Discount codes are issued per vendor rather than per peptide, so any code applies across that vendor's whole catalog. 45 of the 46 vendors listing Tirzepatide publish a PeptideScouter code, worth 5% to 50% off. Applied, the lowest effective price falls from $0.83/mg listed to $0.75/mg at Studz Peptides. Each vendor's code is shown beside its price in the table above.
How much does Tirzepatide cost per mg?
Tirzepatide ranges from $0.83/mg to $13.00/mg across 249 listings from 46 research peptide vendors, normalized to USD per milligram and refreshed daily.
How many vendors sell Tirzepatide?
46 research peptide vendors currently list Tirzepatide on PeptideScouter. We track 249 listings across size and kit variants.
What is the CAS number for Tirzepatide?
Tirzepatide's CAS Registry Number is 2023788-19-2. It is also sold as GLP2-T, TRZ-2, T-GLP2.
