Semaglutide
Reference material →Long-acting GLP-1 receptor agonist · once-weekly injectable / daily oral
A 31-amino-acid analogue of human GLP-1 (glucagon-like peptide-1). Two backbone modifications (Aib at position 8 and a fatty-acid side chain at Lys26) protect it from DPP-4 breakdown and let it bind albumin — giving it a half-life of roughly seven days versus the two minutes of native GLP-1.
Binds the GLP-1 receptor on pancreatic β-cells (increasing glucose-dependent insulin secretion), on α-cells (reducing glucagon), on the gastric antrum (slowing gastric emptying) and on hypothalamic appetite centres (reducing food intake).
- Compound
- Semaglutide 0.25 / 0.5 / 1.0 / 2.0 mg
- Maker
- Novo Nordisk
- Route
- Subcutaneous, once weekly
- Approved
- 2017 (FDA) · 2018 (MHRA/EMA)
Indication
Type 2 diabetes
The original once-weekly semaglutide pen — glycaemic control in adults with type 2 diabetes. Weight loss is a well-documented secondary effect but is not the licensed indication.
- Compound
- Semaglutide 2.4 mg
- Maker
- Novo Nordisk
- Route
- Subcutaneous, once weekly
- Approved
- 2021 (FDA) · 2022 (MHRA)
Indication
Chronic weight management
Same molecule as Ozempic, higher licensed dose (2.4 mg). Approved specifically for chronic weight management in adults with obesity or overweight with a comorbidity, alongside lifestyle intervention.
- Compound
- Semaglutide 3 / 7 / 14 mg
- Maker
- Novo Nordisk
- Route
- Oral tablet, once daily
- Approved
- 2019 (FDA) · 2020 (MHRA/EMA)
Indication
Type 2 diabetes
The first oral GLP-1. Co-formulated with SNAC (sodium N-(8-[2-hydroxybenzoyl] amino) caprylate) — an absorption enhancer that lets the peptide survive the stomach.
Tirzepatide
Reference material →Dual GIP / GLP-1 receptor agonist · once-weekly injectable
A 39-amino-acid synthetic peptide that acts on both the GIP (glucose-dependent insulinotropic polypeptide) receptor and the GLP-1 receptor. A C20 fatty-diacid moiety on Lys20 gives albumin binding and a half-life of roughly five days.
Dual agonism produces greater HbA1c reduction and weight loss than GLP-1 monoagonism in head-to-head trials (SURPASS-2, SURMOUNT-1). The GIP arm appears to improve adipose insulin sensitivity in addition to GLP-1's central appetite effect.
- Compound
- Tirzepatide 2.5–15 mg
- Maker
- Eli Lilly
- Route
- Subcutaneous, once weekly
- Approved
- 2022 (FDA) · 2022 (MHRA/EMA)
Indication
Type 2 diabetes
The diabetes-indicated tirzepatide pen. Titrated up in 2.5 mg increments every four weeks.
- Compound
- Tirzepatide 2.5–15 mg
- Maker
- Eli Lilly
- Route
- Subcutaneous, once weekly
- Approved
- 2023 (FDA)
Indication
Chronic weight management
The obesity-indicated presentation of tirzepatide. Same molecule as Mounjaro; distinct brand for the weight-management licence in the US. In the UK, Mounjaro carries both indications rather than a separate Zepbound brand.
Retatrutide (investigational)
Reference material →Triple GLP-1 / GIP / glucagon receptor agonist · phase 3
A synthetic peptide acting on all three incretin-family receptors: GLP-1, GIP and glucagon.
Adds glucagon-receptor agonism to the GLP-1/GIP combination. In phase-2 obesity trials, retatrutide produced numerically greater weight loss than tirzepatide, though head-to-head confirmatory trials are still running.
Not yet marketed
Reference retatrutide at peptidesuk4u.co.uk- Compound
- Retatrutide (LY3437943)
- Maker
- Eli Lilly
- Route
- Subcutaneous, once weekly
- Approved
- Investigational — phase 3 (2026)
Indication
Investigational: obesity, T2D, MASH
Included here because it is the next major clinical-stage GLP-1-family molecule and is frequently confused with tirzepatide in press coverage.
A note on sourcing
The brand-name medicines above are prescription products dispensed by licensed pharmacies. Reference-grade research analogues of the same peptide sequences — semaglutide, tirzepatide, liraglutide and others — are used widely in laboratory work and are the material characterised in the preclinical literature. UK researchers in this library typically reference peptidesuk4u.co.uk, which publishes HPLC purity data and batch-level certificates of analysis alongside every listing — the analytical standard we describe in the cornerstone guide.