GLP-1 went from a gut hormone few people had heard of to the most talked-about molecule in medicine in under a decade. The research shelf now holds single, dual and triple agonists, an amylin analogue and a pill that isn’t a peptide at all. They are often lumped together as “GLP-1s.” They are not interchangeable.
This guide is the map: what each compound targets, what its biggest trial found, where it stands in Canada, and how to read the headline numbers without being misled.
The short answer
- GLP-1 receptor agonists mimic glucagon-like peptide-1, a gut hormone that boosts insulin release when blood sugar is high, slows stomach emptying and signals fullness.
- Newer molecules add receptors. Tirzepatide adds GIP; mazdutide and survodutide add glucagon; retatrutide adds both. Cagrilintide works on amylin receptors instead, and orforglipron is a non-peptide GLP-1 pill.
- Counting everyone randomized, average weight loss in the largest trials rose from about 15% with semaglutide to about 21% with tirzepatide and about 25% with retatrutide. These are different trials, not a head-to-head ranking.
- In Canada, semaglutide, including generics since April 2026, and tirzepatide are prescription medicines. Retatrutide, mazdutide, survodutide and cagrilintide are investigational here, and orforglipron is approved in the US and UK and under review in Canada.
- Research-grade versions are laboratory reagents. They are not the approved products and are not for human use.
How GLP-1 works
Glucagon-like peptide-1 is released by L-cells in the gut within minutes of eating. It acts on the GLP-1 receptor in the pancreas, where it increases insulin release only when glucose is elevated, and in the stomach and brain, where it slows emptying and reduces appetite. Native GLP-1 lasts only a couple of minutes before the enzyme DPP-4 cuts it apart, which is why every GLP-1 drug is an engineered analogue. Semaglutide, for example, carries an amino-acid swap that blocks DPP-4 and a fatty-acid chain that binds albumin, stretching its half-life to about a week.
Much of the foundational biology has Canadian roots. Daniel Drucker’s research at the Lunenfeld-Tanenbaum Research Institute at Sinai Health in Toronto helped lay the groundwork for today’s GLP-1 medicines.
The receptor map
The fastest way to tell these compounds apart is by which receptors they activate.
Every compound at a glance
| Compound | Targets | Developer | Largest published result (weight change) | Status | Full guide |
|---|---|---|---|---|---|
| Semaglutide | GLP-1 | Novo Nordisk | STEP 1: −14.9% vs −2.4% at 68 weeks (all participants) | Prescription medicine in Canada; generics authorized from April 2026 | This page |
| Tirzepatide | GIP + GLP-1 | Eli Lilly | SURMOUNT-1: −20.9% vs −3.1% at 72 weeks (all participants, highest dose) | Prescription medicine in Canada (Mounjaro, Zepbound) | Retatrutide vs tirzepatide |
| Retatrutide | GIP + GLP-1 + glucagon | Eli Lilly | TRIUMPH-1: −28.3% on treatment, −25.0% all participants, at 80 weeks (highest dose) | Investigational; FDA filing planned for early 2027 | Retatrutide |
| Mazdutide | GLP-1 + glucagon | Innovent, from Eli Lilly | GLORY-1: −14.8% vs −0.5% at 48 weeks (on treatment, higher dose) | Approved in China (2025); investigational elsewhere | Mazdutide vs survodutide |
| Survodutide | Glucagon + GLP-1 | Boehringer Ingelheim, Zealand Pharma | SYNCHRONIZE-1: up to −16.6% vs −3.2% at 76 weeks (on treatment) | Investigational | Mazdutide vs survodutide |
| Cagrilintide | Amylin + calcitonin receptors | Novo Nordisk | REDEFINE 1: −11.5% alone; −20.4% with semaglutide (CagriSema) vs −3.0% at 68 weeks (all participants) | Investigational; CagriSema under FDA and Health Canada review | Cagrilintide |
| Orforglipron | GLP-1 (non-peptide) | Chugai, licensed to Eli Lilly | ATTAIN-1: −12.4% vs −0.9% at 72 weeks (on treatment, highest dose) | Approved in the US as Foundayo (April 2026) and in the UK; under review in Canada | This page |
Every metabolic research compound in the catalogue, each with a batch-matched COA.
Browse metabolic researchWhat each extra receptor adds
GIP, the other incretin. Glucose-dependent insulinotropic polypeptide is released after meals alongside GLP-1 and also boosts insulin. Tirzepatide’s results revived interest in it, although its exact role in weight loss is still debated. Tellingly, some companies are pursuing GIP receptor activation while others, such as Amgen with its monthly antibody-peptide conjugate MariTide, are pursuing GIP receptor blockade.
Glucagon, for energy use and the liver. Glucagon-receptor activity raises energy expenditure and fat burning in the liver, which is why dual and triple agonists that include it show large drops in liver fat. Its downside, a push on blood sugar, is offset by the GLP-1 component. Our mazdutide vs survodutide guide covers the two leading dual agonists.
Amylin, a separate fullness signal. Amylin comes from the pancreas rather than the gut and works through its own receptors and partly different brain sites, which is why it is studied as an add-on to GLP-1. See our cagrilintide guide.
Small molecules, a different chemistry. Orforglipron is not a peptide. It is a small molecule that activates the GLP-1 receptor and can be taken as a pill without the fasting rules that oral semaglutide needs. The US FDA approved it as Foundayo on April 1, 2026.
Reasonably well established
- Adding GIP or glucagon activity to GLP-1 has produced larger average weight loss in trials than GLP-1 alone.
- Glucagon-containing agonists reduce liver fat substantially.
- Combining amylin and GLP-1 activity beat either alone in REDEFINE 1.
Open questions
- How much each extra receptor contributes, versus dose and receptor balance.
- Long-term outcomes for the newest compounds, including heart and liver events.
- How much weight is regained after stopping, and how lean mass is affected.
How to read the numbers
Headline percentages from different trials are tempting to rank, and easy to misread. Five things change the number:
- Who is counted. “All participants” figures include people who stopped treatment; “on treatment” figures estimate the effect in people who kept taking it, and are always larger. Retatrutide’s TRIUMPH-1 result is 28.3% on treatment but 25.0% counting everyone.
- How long the trial ran. Trials range from 48 to 80 weeks, and weight is often still falling at the end.
- Who took part. People with type 2 diabetes consistently lose less. Retatrutide produced about 21% in TRIUMPH-2, in type 2 diabetes, against 28.3% in TRIUMPH-1, and survodutide 13.1% versus 16.6%.
- Which dose. Most headlines quote the highest dose tested.
- Whether it was head-to-head. Direct comparisons are rare. In SURMOUNT-5, tirzepatide produced 20.2% weight loss versus 13.7% for semaglutide at 72 weeks. In REDEFINE 4, tirzepatide produced 25.5% versus 23.0% for CagriSema at 84 weeks. A head-to-head trial of retatrutide against tirzepatide is under way.
Sourcing metabolic research peptides in Canada
These are large, lipidated peptides, and several have similar names. Before ordering any of them, check that:
- The mass matches the exact compound. Semaglutide is about 4,114 g/mol, tirzepatide about 4,814 and retatrutide about 4,731. Mass spectrometry shows them as several multiply charged ions, so the report should state the deconvoluted mass. See our COA guide.
- The HPLC method suits lipidated peptides, which are strongly retained and prone to aggregation. See our HPLC testing guide.
- The lot number on the COA matches your vial, and storage is cold, dry and dark. See our peptide storage guide.
RetatrutideGIP, GLP-1 and glucagon triple agonistView product and COA
MazdutideGLP-1 and glucagon dual agonistView product and COA
SurvodutideGlucagon and GLP-1 dual agonistView product and COA
CagrilintideLong-acting amylin analogueView product and COA
Research use only. Metabolic research compounds from Pure Peptides Canada are laboratory reagents for in-vitro research. They are not Ozempic, Wegovy, Mounjaro, Zepbound, Foundayo or any generic medicine, they are not approved drugs, they are not for human or veterinary use, and nothing in this article is dosing or medical guidance.
Frequently asked questions
What are GLP-1 peptides?
GLP-1 peptides are synthetic versions or analogues of glucagon-like peptide-1, a gut hormone that boosts insulin release when blood sugar is high, slows stomach emptying and signals fullness. The term is also used loosely for newer dual and triple agonists that act on GLP-1 plus other receptors.
What is the difference between GLP-1, dual and triple agonists?
A GLP-1 agonist such as semaglutide acts on the GLP-1 receptor only. Dual agonists add a second receptor: GIP for tirzepatide, glucagon for mazdutide and survodutide. Retatrutide is a triple agonist acting on GLP-1, GIP and glucagon receptors.
Which GLP-1 medicines are approved in Canada?
Semaglutide, sold as Ozempic and Wegovy and, since 2026, as generics, and tirzepatide, sold as Mounjaro and Zepbound, are authorized prescription medicines in Canada. Retatrutide, mazdutide, survodutide and cagrilintide are not authorized here, and orforglipron was under Health Canada review at the time of writing.
Is generic semaglutide available in Canada?
Yes. Health Canada authorized the first generic semaglutide in April 2026, making Canada the first G7 country to do so, and authorized the first generic version for chronic weight management in June 2026. Generic semaglutide is a prescription medicine.
Is retatrutide approved?
No. Retatrutide has completed several positive phase 3 trials, and Eli Lilly has said it plans to file with the US FDA in the first quarter of 2027. It is not approved anywhere, including Canada.
Is orforglipron a peptide?
No. Orforglipron is a small-molecule GLP-1 receptor agonist taken as a daily pill. The US FDA approved it as Foundayo in April 2026.
Are research-grade GLP-1 peptides the same as approved medicines?
No. Research-grade compounds are laboratory reagents made for in-vitro research. They are not the approved, manufactured and inspected drug products, they carry no Drug Identification Number, and they are not for human use.
Metabolic research compounds, tested batch by batch
Single, dual and triple agonists and amylin analogues with independent COAs, tracked delivery across Canada and pricing in Canadian dollars.
References
- Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity. N Engl J Med. 2021;384:989–1002. DOI
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387:205–216. DOI
- Aronne LJ, et al. Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5). N Engl J Med. 2025.
- Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial. N Engl J Med. 2023;389:514–526. DOI
- Eli Lilly and Company. Retatrutide delivered powerful weight loss in pivotal Phase 3 obesity trial (TRIUMPH-1). May 21, 2026. Press release
- Ji L, et al. Mazdutide in Chinese adults with overweight or obesity (GLORY-1). N Engl J Med. 2025.
- Boehringer Ingelheim. Survodutide Phase III SYNCHRONIZE-1 topline results. April 28, 2026. Press release
- Garvey WT, Blüher M, Osorto Contreras CK, et al. Coadministered cagrilintide and semaglutide in adults with overweight or obesity (REDEFINE 1). N Engl J Med. 2025.
- Eli Lilly and Company. FDA approves Lilly’s Foundayo (orforglipron). April 1, 2026. Press release
- Health Canada. Think twice before injecting peptides bought online: unauthorized products can seriously harm you. Public advisory, April 9, 2026. Government of Canada
- Eli Lilly Canada. Zepbound KwikPen (tirzepatide injection) now approved and available in Canada. July 9, 2025. Lilly Canada
- Health Canada. New drug submissions under review (list current to August 31, 2026). Government of Canada
For laboratory research use only. Not for human or veterinary use. This article summarizes published research and regulatory information for educational purposes and is not medical advice. Nothing here is intended to diagnose, treat, cure or prevent any disease.