Entry 0008Rev 1.1GIP and GLP-1 dual agonist

Tirzepatide

39-residue lipidated peptide · C225H348N48O68

Reviewed

2 Nov 2026

Scientific editor

[Name, PhD]

References

6 sources

Tirzepatide is a 39-residue peptide from Eli Lilly that acts on two hormone receptors, GIP and GLP-1. It is built on the GIP sequence and carries a C20 fatty chain that binds albumin, giving it a once-weekly dose.1

It is a licensed prescription medicine: Mounjaro for type 2 diabetes since 2022, and for weight management as Zepbound in the US and Mounjaro in the UK since 2023. Peptidarium sells it as a laboratory research material, tested lot by lot, not as a medicine.

Residues

39

Avg mass

4813.5 g/mol

SURMOUNT-1, top dose

−20.9% at 72 wk

Licensed

Yes, prescription

01

Identity

Value
DeveloperEli Lilly
CodeLY3298176
ReceptorsGIP and GLP-1
Side chainC20 diacid on lysine 20, through glutamic acid and two AEEA linkers
FormulaC225H348N48O68
Avg mass4813.5 g/mol
CAS2023788-19-2
BrandsMounjaro, Zepbound
Tirzepatide residue chain diagram, with the lipidated lysine marked in red
Fig. 1. The 39-residue chain. X is Aib; the red residue is lysine 20, which carries the C20 diacid side chain.
02

History

  1. Approved in the US as Mounjaro for type 2 diabetes, on nine SURPASS trials in 7,769 people.1

  2. Approved in the EU.1

  3. SURMOUNT-1 published: 72 weeks in adults with obesity.2

  4. US approves Zepbound for weight management; the MHRA extends Mounjaro to weight management in the UK.1

  5. SURMOUNT-5 compares it head to head with semaglutide.3

  6. UK factory raid seizes 2,000 pens labelled tirzepatide or retatrutide.4

03

What the trials measured

TrialPeopleDurationMain resultSource
SURPASS programme7,769 with type 2 diabetes across nine trials40–104 weeksHbA1c and weight against placebo, insulin and semaglutide 1 mg[1]
SURMOUNT-1Adults with obesity, no diabetes72 weeksWeight −15.0% (5 mg), −19.5% (10 mg), −20.9% (15 mg) vs −3.1% placebo[2]
SURMOUNT-5751 adults with obesity72 weeksWeight −20.2% on tirzepatide vs −13.7% on semaglutide[3]
04

Regulatory and sport status

As of this revision. General information, not legal advice.

WhereStatus
UKLicensed prescription-only medicine (Mounjaro). The MHRA raided unlicensed sellers in October 2025 and February 2026.4,5
EU and USLicensed prescription medicine.1
SportNot named on the WADA list. As an approved medicine it does not fall under class S0.6
05

In our store

Peptidarium sells tirzepatide as a research material for laboratory use, in 10 mg lyophilised vials. Each lot is tested by an independent lab for purity by HPLC and identity by mass spectrometry, and its certificate is published in the lot register. It is the same molecule as the licensed medicine but is not that medicine: it is not made, licensed or supplied for human or veterinary use.

06

Open questions

  1. How much of the extra weight loss over semaglutide comes from the GIP receptor, and how.
  2. Weight regain after stopping, which extension studies are still reporting.
  3. Cardiovascular outcomes in people without diabetes, which were still being studied at this revision.
07

Common questions

Is tirzepatide the same as Mounjaro?

Yes. Mounjaro and Zepbound are brand names for tirzepatide.

Is tirzepatide stronger than semaglutide?

In the SURMOUNT-5 trial, people on tirzepatide lost 20.2% of body weight at 72 weeks against 13.7% on semaglutide.

Is it banned in sport?

No. It is not named, and as an approved medicine it does not fall under class S0.

Do you sell tirzepatide?

Yes, as a research material for laboratory use only, tested lot by lot. It is not the licensed medicine and is not for human or veterinary use.

How does it differ from retatrutide?

Tirzepatide acts on two receptors, GIP and GLP-1. Retatrutide adds the glucagon receptor and is still investigational.

—

See also

Semaglutide Entry 0007Retatrutide Entry 0005Metabolic ShelfSemaglutide vs tirzepatide vs retatrutide Comparison
08

References

  1. Wikipedia. Tirzepatide, for identifiers and approval dates, checked 2 Nov 2026.
  2. Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387:205–216. PMID 35658024
  3. Aronne LJ, et al. Tirzepatide as compared with semaglutide for the treatment of obesity. N Engl J Med. 2025;393(1):26–36. doi:10.1056/NEJMoa2416394
  4. Reuters. UK seizes record haul of illegal weight-loss drugs in factory raid. 24 October 2025.
  5. The Pharmacist. Almost 2,000 unauthorised weight loss drugs seized in MHRA raids. 26 February 2026. thepharmacist.co.uk
  6. World Anti-Doping Agency. The 2026 Prohibited List. wada-ama.org

Peptidarium Library. Tirzepatide (entry 0008), revision 1.1, 3 November 2026. peptidarium.com/library/tirzepatide

09

Revision history

RevDateChangeBy
1.02 Nov 2026Entry created.[Scientific editor]
1.13 Nov 2026Store section updated: tirzepatide is now stocked as a lot-tested research material.[Scientific editor]

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