Pillar reference for tirzepatide, the synthetic dual GLP-1 / GIP receptor agonist examined in the SURMOUNT trial programme. Covers mechanism, pharmacokinetics, weight-management endpoints by week, head-to-head data, and UK sourcing standards. For in-vitro and preclinical research use only.
What is tirzepatide?
Tirzepatide is a synthetic 39-amino-acid peptide engineered as a dual agonist at the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. The molecule incorporates a C20 fatty diacid moiety on Lys20, conferring binding to serum albumin and an elimination half-life of approximately 5 days in research participants — supporting once-weekly subcutaneous administration in clinical research.
Tirzepatide is separately marketed by Eli Lilly as Mounjaro (type 2 diabetes) and Zepbound / Mounjaro (chronic weight management) under MHRA, FDA, and EMA marketing authorisations. Material supplied by Peptides Lab UK is research-grade for in-vitro and preclinical use only and is not the licensed pharmaceutical product.
Mechanism — dual incretin receptor agonism
- GLP-1 receptor activation — drives glucose-dependent insulin secretion, glucagon suppression, delayed gastric emptying, central satiety signalling.
- GIP receptor activation — adds nutrient-sensitive insulinotropic activity, white-adipose-tissue lipid handling effects, and central satiety effects synergistic with GLP-1.
- Combined effect — preclinical and clinical research has characterised additive effects on body weight, HbA1c, hepatic-fat fraction, and lipoprotein profile beyond GLP-1 monoagonism.
SURMOUNT trial programme — body weight by week
| Trial | Population | Endpoint | Tirzepatide 15 mg result |
|---|---|---|---|
| SURMOUNT-1 | Adults with obesity, no diabetes | 72-week BW change | ~ -22.5% |
| SURMOUNT-2 | Adults with obesity + T2D | 72-week BW change | ~ -15.7% (10 mg dose) |
| SURMOUNT-3 | Intensive lifestyle lead-in then RCT | 72-week BW change after lead-in | Additional ~ -18.4% |
| SURMOUNT-4 | Withdrawal RCT after open-label lead-in | BW maintenance vs placebo | Continued treatment maintains loss |
| SURMOUNT-5 | Head-to-head vs semaglutide 2.4 mg | 72-week BW change | Tirzepatide superior |
For week-by-week dose-response and long-term maintenance data, see the tirzepatide weight-loss timeline reference. For the head-to-head SURMOUNT-5 comparison vs semaglutide, see the tirzepatide vs semaglutide reference.
Side-effect profile (research observations)
The SURMOUNT trial-programme safety data show predominantly gastrointestinal adverse events at the published doses: nausea (24–33% incidence), vomiting (8–12%), diarrhoea (15–22%), constipation (10–14%), with most events mild-to-moderate and titration-related. Discontinuation for adverse events was 4–7% across the SURMOUNT programme. Full mechanism-and-mitigation reference: GLP-1 class side-effects reference.
Pharmacokinetics summary
| Parameter | Tirzepatide |
|---|---|
| Molecular weight | ~4,813 Da |
| Route | Subcutaneous (research) |
| Tmax | ~24 hours |
| Steady-state | ~4 weeks |
| Half-life | ~5 days |
| Elimination | Peptide-backbone proteolysis; renal/biliary metabolite excretion |
UK sourcing & analytical standards
Research-grade tirzepatide must be supplied with batch-level HPLC purity, mass-spectrometry identity confirmation (observed mass within 0.1 Da of theoretical 4,813), and bacterial endotoxin quantification. Peptides Lab UK supplies tirzepatide with an Optima Labs (UK) Certificate of Analysis on every batch, typical 99.0–99.7% HPLC purity, with same-day UK dispatch.
Available SKU
FAQs — tirzepatide in UK research
What is tirzepatide?
Tirzepatide is a synthetic 39-amino-acid dual GLP-1/GIP receptor agonist examined in the SURMOUNT trial programme for body-weight and glycaemic endpoints in research participants with obesity and type 2 diabetes.
Is tirzepatide MHRA-approved in the UK?
Tirzepatide (as Mounjaro) is MHRA-authorised for type 2 diabetes and chronic weight management as a prescription medicine in the UK. Material supplied by Peptides Lab UK is research-grade for in-vitro and preclinical research use only and is not the MHRA-authorised pharmaceutical product.
How does tirzepatide compare to semaglutide?
Semaglutide is a single GLP-1 agonist; tirzepatide is a dual GLP-1/GIP agonist. The SURMOUNT-5 head-to-head trial demonstrated greater body-weight reduction with tirzepatide at 72 weeks. See the comparison reference.
How does tirzepatide compare to retatrutide?
Tirzepatide is dual-receptor (GLP-1 + GIP); retatrutide adds glucagon receptor activity for triple agonism (GLP-1 + GIP + GCGR). TRIUMPH-1 Phase 2 retatrutide data show numerically greater body-weight reduction (~24.2% at 48 weeks, 12 mg) than published tirzepatide endpoints, pending Phase 3 confirmation.
Last updated: 26 April 2026. Reviewed by William, Lead Research Editor, Peptides Lab UK. For in-vitro and preclinical research use only.
