GLP-1 Peptide Comparison Guide: Retatrutide, Tirzepatide, Semaglutide, Cagrilintide
Published: 2026-08-03 · Last updated: 2026-08-03
The GLP-1 family is one of the most active areas of research peptide interest right now. This guide compares the four most-requested compounds — retatrutide, tirzepatide, semaglutide, and cagrilintide — from a Canadian research-buyer perspective. Nothing here is dosing guidance or medical advice. This is a plain-English overview of how the compounds differ, how they compare on availability and price in the Canadian market, and what to know before ordering.
What are the four compounds and how are they related?
Semaglutide is a GLP-1 receptor agonist — a peptide that binds and activates the GLP-1 receptor. It is the most established of the group by a wide margin, with the longest research history and the widest availability. In the research peptide market, it is the reference compound most other GLP-1s get compared to.
Tirzepatide is a dual agonist — it activates both the GLP-1 receptor and the GIP receptor. The idea is that hitting two related pathways at once produces different downstream effects than hitting either alone. Research literature and market interest have grown quickly since it became widely available.
Retatrutide is a triple agonist — GLP-1, GIP, and glucagon receptors. It is the newest of the four in the research peptide market and the most complex to manufacture, which is why it typically carries the highest per-mg price. Cagrilintide is different: it is an amylin analogue, not a GLP-1 agonist directly, but it is often studied in combination with GLP-1 compounds because of the complementary pathways.
How do the compounds differ on stability and handling?
All four are large, complex peptides — noticeably bigger and more structurally intricate than something like BPC-157 or TB-500. That size makes them more sensitive to physical stress: freeze-thaw cycles, mechanical agitation (shaking), and light exposure all take more of a toll than they would on a simpler sequence.
Practically, this means the aliquoting discipline covered in the storage guide matters more here than average. Reconstitute once, split into single-use aliquots, freeze them, and stop touching the master. Skipping this step and just refreezing the master vial after each use is where you will notice degradation fastest with a GLP-1 compound.
Reconstitution follows the standard approach — bacteriostatic water, trickle down the vial wall, swirl gently. See the reconstitution basics guide for the general process. GLP-1 peptides are not exceptionally difficult to dissolve, but be patient with them and do not shake.
How does pricing compare across the four?
Semaglutide is the cheapest per mg of the four in the Canadian research market. It is a well-established compound with mature manufacturing, and prices reflect that. It typically comes in the widest range of vial sizes (5 mg, 10 mg, occasionally larger) because demand is steady across all tiers.
Tirzepatide is more expensive than semaglutide but has become more accessible over the last year as production has scaled. Retatrutide is the most expensive per mg by a meaningful margin — the manufacturing complexity of a triple agonist plus the newer status keeps prices high. Cagrilintide is somewhere between semaglutide and tirzepatide, depending on the vendor.
Our vial strengths guide covers how per-mg pricing typically works within a single compound (bigger vials cheaper per mg). That pattern holds for all four GLP-1s. Live pricing is on individual product pages in the peptides catalogue.
What about availability in the Canadian market?
Semaglutide is almost always available at Canadian research peptide vendors. It is one of the most-stocked SKUs across the market and shortages are uncommon. Tirzepatide has become broadly available in the last year but experiences occasional supply gaps.
Retatrutide is intermittent. Because it is newer and demand often outpaces supply, most Canadian vendors stock it in limited quantities and it moves fast when it does come in. Cagrilintide is a specialty item — some vendors carry it, some do not. If you specifically need it, plan ahead.
For anything time-sensitive, order sooner rather than later. Waiting on a specific GLP-1 compound is a common frustration for Canadian research buyers, and cross-border ordering from US vendors carries the customs and FX overhead covered in our Canadian vs US guide.
How do I evaluate GLP-1 CoAs specifically?
Same fundamentals as any peptide: batch-specific, from a named third-party lab, with both HPLC purity and mass-spec identity results. What is different about GLP-1s is that the mass-spec verification is more important than average because these are large molecules where a small manufacturing error (a missing residue, a modified side chain) can look like a similar compound on paper but behave very differently.
Look for a mass-spec result that matches the expected molecular weight closely. Small deviations of a few daltons matter for peptides of this size. Purity by HPLC should be 98% or higher for a reputable research supplier — some vendors quote 99%+ on GLP-1s.
Our CoA verification guide covers the step-by-step process, and the HPLC and mass spec guide explains what those two techniques actually measure. Both apply directly to evaluating GLP-1 CoAs.
Should I stock all four for comparative research?
Depends entirely on what you are researching. If your work is specifically comparing receptor-target profiles across the GLP-1 family, then yes — having the four side by side makes sense. If you are just exploring the space and have not landed on a research question yet, start with one (usually semaglutide, given cost and availability) and expand from there.
Ordering all four at once is expensive and creates a storage problem, because none of them is a compound you want to keep in the fridge indefinitely after reconstitution. Better to order one, work through it, and only then order the next. This staged approach also lets you verify each vendor's product quality before you commit more money.
The first-time buyer checklist has the broader framework for scaling into a new peptide class. The catalogue shows what we currently stock across the four compounds.
Questions Canadian buyers ask
What are GLP-1 peptides actually studied for?
In published research, they are studied primarily for their effects on blood sugar regulation, appetite signalling, and body composition in animal and clinical models. In a research context, that is what the literature is about — this is not medical advice and nothing here is a dosing suggestion.
Are these all the same class of molecule?
They are related but distinct. GLP-1 receptor agonists (like semaglutide) act on one specific receptor. Dual and triple agonists (like tirzepatide and retatrutide) act on multiple receptors simultaneously. Cagrilintide is an amylin analogue, a different but often paired pathway. The research literature treats them as a family rather than a single drug class.
Which of these are hardest to source in Canada?
Retatrutide is the newest and often has the tightest supply. Tirzepatide is also intermittent. Semaglutide is more established and typically more available. Cagrilintide is a specialty item. All four are stocked selectively by Canadian research peptide vendors — check current availability before planning around any specific compound.
How does the pricing compare across the four?
Retatrutide is the most expensive per mg (newest and hardest to make). Tirzepatide is next. Semaglutide is significantly cheaper. Cagrilintide sits closer to semaglutide. Prices move around with supply and demand — the current numbers are on individual product pages.
Do they all need the same reconstitution and storage?
Similar but not identical. All four are large peptides sensitive to freeze-thaw, so aliquot discipline matters. Bacteriostatic water is the standard solvent for all four. Storage in the fridge after reconstitution is standard. Check the CoA for compound-specific stability notes.