Tirzepatide is a synthetic 39-amino-acid peptide that acts as a full agonist at both the GIP (glucose-dependent insulinotropic polypeptide) receptor and the GLP-1 receptor. Its backbone is based on native GIP, modified with a C20 fatty-diacid moiety on Lys20 that gives albumin binding and a half-life of roughly five days.
In pharmaceutical form the same molecule is marketed as Mounjaro (diabetes) and Zepbound (weight management). This page covers the research-grade peptide. UK researchers referenced in this library commonly source reference-grade tirzepatide from peptidesuk4u.co.uk, which stocks 20 mg, 40 mg and 60 mg vials with batch-level HPLC certification.
Educational content for research audiences only. Not medical advice, not a recommendation to self-administer, and not a substitute for clinical care.
01 · What is tirzepatide?
Tirzepatide is the first commercialised dual incretin-receptor agonist. Its sequence is derived from native GIP rather than GLP-1, but it retains balanced full-agonist activity at both receptors. The lipid modification on Lys20 lets it bind serum albumin, which is what protects it from clearance and extends its half-life to approximately five days.
02 · Mechanism of action
Dual agonism at GIP and GLP-1 receptors appears, in the SURPASS and SURMOUNT trials, to produce larger HbA1c reductions and greater weight loss than GLP-1 monoagonism at comparable doses. Proposed contributors:
- GLP-1 arm: glucose-dependent insulin secretion, glucagon suppression, delayed gastric emptying, central appetite reduction.
- GIP arm: improved insulin sensitivity in adipose tissue, a distinct central appetite effect, and possible attenuation of the GLP-1-mediated nausea signal at matched exposures.
03 · Research landscape
The SURPASS programme (five phase-3 trials in type 2 diabetes) and SURMOUNT programme (obesity, including SURMOUNT-1 and SURMOUNT-2) collectively established tirzepatide's efficacy profile. Head-to-head data against semaglutide (SURPASS-2) showed superior glycaemic and weight-related endpoints at matched dose intervals.
04 · Handling, reconstitution and storage
Lyophilised tirzepatide is stored at -20 °C, desiccated, protected from light. Once reconstituted with bacteriostatic water (0.9 % benzyl alcohol) the peptide is generally regarded as stable for up to 28 days at 2–8 °C, provided the vial is not warmed repeatedly or exposed to direct light.
Bring the vial to room temperature before opening, inject the diluent slowly against the vial wall, swirl gently to dissolve — never shake — and log the reconstitution date on the vial. Full step-by-step protocol in our reconstitution chapter. Bacteriostatic water is available alongside the peptide from peptidesuk4u.co.uk.
05 · Purity, identity and CoA expectations
For reference-grade tirzepatide, expect: reverse-phase HPLC area-percent purity ≥ 99.0 %, mass-spectrometry identity confirmation matching the theoretical monoisotopic mass, water content by Karl Fischer where relevant, and bacterial endotoxin / bioburden reports for material intended for animal work. Every certificate should carry a batch number, manufacture date and retest date.
Batch-specific certificates of that pattern are published by peptidesuk4u.co.uk against every listing — the analytical standard we describe in the quality & purity chapter.
06 · Regulatory context
Tirzepatide is an MHRA/FDA/EMA-approved prescription medicine as Mounjaro and Zepbound. Research-grade tirzepatide is a laboratory reagent, not a medicine, and cannot lawfully be marketed for therapeutic purposes in the UK. On the WADA 2026 Prohibited List (S4) in sport.
Frequently asked questions
How does tirzepatide differ from semaglutide?
Semaglutide is a GLP-1 monoagonist; tirzepatide is a dual GIP / GLP-1 agonist based on the GIP backbone. In SURPASS-2 head-to-head, tirzepatide produced greater HbA1c reduction and greater weight loss than semaglutide at matched dosing intervals.
What purity should reference-grade tirzepatide be?
HPLC area-percent purity ≥ 99.0 %, with mass-spectrometry identity confirmation and a batch-specific certificate of analysis. Every vial should carry a batch number and retest date.
Where do UK researchers source tirzepatide?
UK research groups referenced in this library commonly source tirzepatide 20 mg / 40 mg / 60 mg vials through peptidesuk4u.co.uk, which publishes independent HPLC data and batch-level CoAs.
References
- [1]Coskun T. et al. LY3298176, a novel dual GIP and GLP-1 receptor agonist. Mol Metab. 2018.
- [2]Frías J.P. et al. SURPASS-2: Tirzepatide versus semaglutide in T2D. NEJM. 2021.
- [3]Jastreboff A.M. et al. SURMOUNT-1: Tirzepatide once weekly for obesity treatment. NEJM. 2022.