For research purposes only. Not for human use. The compounds discussed here are sold to laboratories as research chemicals. Nothing on this page is medical advice, a substitute for an approved prescription medicine, or a protocol for administration.
What This Guide Covers
The incretin class has grown from one receptor target to three in under a decade, and the research-peptide market has followed. This guide maps the compounds a laboratory is likely to encounter (semaglutide, liraglutide, tirzepatide, retatrutide, survodutide, mazdutide and cagrilintide), summarises the published trials that define each one, and then uses the peptides.so listings database to show what those compounds cost across 119 indexed suppliers, how many suppliers carry each, and where the pricing spread comes from. The final sections cover what to check on a certificate of analysis for a fatty-acid-conjugated peptide and what independent test purchases of online semaglutide have found.
Prices and supplier counts below were pulled from the platform database on 27 September 2026 (listings price-checked through 28 September 2026). Live figures are on each compound page.
The Compound Classes
Selective GLP-1 receptor agonists. Semaglutide and liraglutide are GLP-1 analogues modified with a fatty-acid side chain so they bind albumin and survive in circulation for days rather than minutes. Semaglutide's C18 diacid chain gives it a half-life of roughly one week; liraglutide's C16 chain gives roughly a day. Both have the same 31-residue backbone logic and both are approved medicines in their pharmaceutical forms, which is why they have the deepest evidence base of any compound in this guide. Research profiles: semaglutide and liraglutide.
GIP/GLP-1 dual agonists. Tirzepatide (Eli Lilly's LY3298176) is a 39-residue peptide built on the GIP backbone with a C20 diacid chain, engineered to activate both the GIP and the GLP-1 receptor. Coskun and colleagues described its discovery in Molecular Metabolism in 2018, reporting imbalanced activity that favoured the GIP receptor and a phase 1 programme in which body-weight reductions were dose-dependent and the most frequent adverse events were gastrointestinal (Coskun et al., 2018). Research profile: tirzepatide.
Glucagon/GLP-1 dual agonists. Survodutide (Boehringer Ingelheim's BI 456906) and mazdutide (Innovent/Lilly's IBI362) add glucagon receptor agonism, which increases energy expenditure and liver fat oxidation, to GLP-1 receptor agonism. Neither is approved anywhere as of this writing; both are in phase 3.
Triple agonists. Retatrutide (LY3437943) activates the GIP, GLP-1 and glucagon receptors from a single peptide. It is the most advanced triple agonist and the highest-priced compound in this guide on the platform. Research profile: retatrutide.
Amylin analogues. Cagrilintide is a long-acting amylin analogue developed to be co-administered with semaglutide (the combination is called CagriSema). Amylin acts on satiety through a different receptor family, so this pairing is a mechanistic combination rather than a single multi-receptor molecule.
Oral small molecules. Orforglipron is a non-peptide GLP-1 receptor agonist taken as a daily tablet. It appears in a handful of platform listings as capsules or tablets. It is not a peptide and the reconstitution and storage guidance elsewhere on this site does not apply to it.
What the Published Trials Show
The table below reports the headline body-weight outcome of the largest published trial for each compound. Trial arms are named as the papers name them; the figures identify the results, not a protocol.
| Compound | Trial (journal, year) | Population | Duration | Weight change vs placebo | Source |
|---|---|---|---|---|---|
| Semaglutide | STEP 1 (NEJM, 2021) | 1,961 adults with overweight or obesity | 68 weeks | −14.9% vs −2.4% | PMID 33567185 |
| Tirzepatide | SURMOUNT-1 (NEJM, 2022) | 2,539 adults with obesity | 72 weeks | −15.0% to −20.9% across three arms vs −3.1% | PMID 35658024 |
| Retatrutide | Phase 2 (NEJM, 2023) | 338 adults with obesity | 48 weeks | −8.7% to −24.2% across arms vs −2.1% | PMID 37366315 |
| CagriSema | REDEFINE 1 (NEJM, 2025) | 3,417 adults with overweight or obesity | 68 weeks | −20.4% vs −3.0% | PMID 40544433 |
| Survodutide | SYNCHRONIZE-1 (NEJM, 2026) | 725 adults with obesity | 76 weeks | −12.2% and −13.0% in two arms vs −5.4% | PMID 42253238 |
| Orforglipron | Phase 2 (NEJM, 2023) | 272 adults with obesity | 36 weeks | −9.4% to −14.7% across arms vs −2.3% | PMID 37351564 |
Two further results bear on the choice of comparator. In SURPASS-2, an open-label 40-week trial in 1,879 people with type 2 diabetes, all three tirzepatide arms lowered glycated haemoglobin more than the semaglutide comparator arm, with estimated differences of −0.15 to −0.45 percentage points (Frías et al., 2021). In SUSTAIN-6, a 104-week cardiovascular outcomes trial in 3,297 people with type 2 diabetes, the primary composite of cardiovascular death, non-fatal myocardial infarction or non-fatal stroke occurred in 6.6% of the semaglutide group and 8.9% of the placebo group (hazard ratio 0.74) (Marso et al., 2016). A 2025 Cochrane review pooled the tirzepatide obesity trials with a minimum six-month follow-up and rated weight, adverse events, major adverse cardiovascular events, quality of life and mortality as its critical outcomes (Franco et al., 2025).
Gastrointestinal adverse events are the common thread. In REDEFINE 1 they affected 79.6% of the CagriSema group against 39.9% on placebo; in SYNCHRONIZE-1, 80.9% and 89.7% of the two survodutide arms against 47.9% on placebo. Retatrutide's phase 2 paper also reported dose-dependent heart-rate increases that peaked at 24 weeks and declined afterwards.
Platform Market Data: Who Sells What, and for How Much
Across the 10,863 priced listings on peptides.so (list price of at least $5, 119 suppliers), the platform-wide median list price is $71.50. Every GLP-1-class compound sits above it.
| Compound (platform row) | Listings | Suppliers | Median list price | Range | Compound page |
|---|---|---|---|---|---|
| Semaglutide | 51 | 23 | $119.99 | $30 to $539.99 | /peptide/semaglutide |
| Tirzepatide | 56 | 20 | $185.50 | $36 to $1,300 | /peptide/tirzepatide |
| Retatrutide | 58 | 27 | $169.00 | $45 to $1,780 | /peptide/retatrutide |
| Cagrilintide 10 mg | 69 | 53 | $99.99 | $37.32 to $650 | /peptide/cagrilintide-10mg |
| Survodutide 10 mg | 24 | 24 | $111.99 | $70 to $930 | /peptide/survodutide-10mg |
| Mazdutide 10 mg | 22 | 21 | $115.22 | $50 to $555 | /peptide/mazdutide-10mg |
| Liraglutide | 5 | 4 | $99.00 | $40 to $304.64 | /peptide/liraglutide |
Cagrilintide has the widest supplier base of any compound in the class (53 suppliers), wider than semaglutide itself. Liraglutide, the oldest compound here, is nearly absent from the research market at four suppliers.
The ranges look alarming until vial size is accounted for. The platform's raw product rows mix 5 mg, 10 mg, 30 mg and 60 mg vials and, in some cases, ten-vial kits. Parsing the vial size from each store's product URL gives size-pinned medians:
| Compound | Vial size | Listings | Suppliers | Median list price |
|---|---|---|---|---|
| Semaglutide | 5 mg | 12 | 10 | $97.50 |
| Semaglutide | 10 mg | 12 | 9 | $144.50 |
| Tirzepatide | 5 mg | 6 | 5 | $120.49 |
| Tirzepatide | 10 mg | 11 | 8 | $140.00 |
| Tirzepatide | 30 mg | 9 | 7 | $259.00 |
| Tirzepatide | 60 mg | 5 | 4 | $360.00 |
| Retatrutide | 10 mg | 13 | 10 | $149.00 |
| Retatrutide | 20 mg | 5 | 4 | $216.00 |
| Cagrilintide | 5 mg | 19 | 19 | $90.00 |
| Cagrilintide | 10 mg | 18 | 17 | $145.00 |
| Survodutide | 10 mg | 10 | 10 | $107.50 |
| Mazdutide | 10 mg | 6 | 6 | $162.00 |
At the 10 mg size, tirzepatide ($140), semaglutide ($144.50), cagrilintide ($145) and retatrutide ($149) are priced within $10 of each other. The premium that separates the compounds at the raw-row level comes mostly from tirzepatide's 30 mg and 60 mg vials and from retatrutide kits, not from a per-milligram premium on the newer molecules. Suppliers with fewer than 10 listings in a size are quoted above for completeness; treat those medians as indicative rather than platform-grade.
Sixty-five of the 165 semaglutide, tirzepatide and retatrutide listings (39%) carried a sale price below list at the time of the query. Compare at the sale price if a supplier discounts its whole catalogue, and at list if it discounts only a few lines; the cost calculator accepts either.
Coded product names
A noticeable share of GLP-1-class listings use coded names rather than compound names: "GLP-1 (S)", "GLP-2 (T)", "GLP-3 (R)", "AMP-3P 48mg (GLP-3RT)", "Tirz (GLP-1, GIP RA) 10mg". On the platform these coded rows carry 54 listings across 28 suppliers for the "GLP3 (R)" row and 71 across 27 for "GLP-2 (T)", so they are not a fringe. The letter in parentheses is the first letter of the compound the store means (S for semaglutide, T for tirzepatide, R for retatrutide), and the number is the store's own generation label, not a pharmacological one. Coded rows are excluded from the compound tables above because the platform cannot verify that a "GLP-3 (R)" vial contains retatrutide. A certificate of analysis that names the compound and reports its mass is the only way to close that gap.
Multi-compound coverage
Thirty-three suppliers carry at least one of semaglutide, tirzepatide or retatrutide under its own name. Fifteen carry all three, seven carry two and eleven carry one. Four suppliers carry all six of the named compounds in the first table (semaglutide, tirzepatide, retatrutide, cagrilintide, survodutide and mazdutide). Sixty suppliers carry at least one of the three newer compounds (cagrilintide, survodutide, mazdutide), which is nearly twice the number carrying the three established ones, a sign of how quickly the research market moves to whatever is newest in phase 3. The stack builder filters suppliers by the set of compounds a study requires, so a laboratory sourcing a semaglutide-plus-cagrilintide comparison can see which storefronts cover both without opening 33 tabs.
The testing gap
None of the 181 supplier rows on the platform has a non-zero testing score, and none has a certificate-of-analysis URL on file. That is a platform-wide baseline, not a mark against any one storefront, and it means the platform cannot rank GLP-1 suppliers by documentation. Price comparison is what the data supports; purity verification is the buyer's job. The supplier checklist lists the documents to request before an order.
What Independent Test Purchases Have Found
The most direct evidence on the quality of online semaglutide comes from a 2024 market-surveillance study in the Journal of Medical Internet Research. Ashraf and colleagues collected 1,080 search-result links, identified 317 online pharmacies (134 of them illegal), made test purchases, and analysed the products by LC-MS, sterility and endotoxin testing. Visual inspection found non-compliance in 59% to 63% of the criteria evaluated. The lyophilised samples were free of viable microorganisms but every sample contained endotoxin (2.16 to 8.95 EU/mg). Semaglutide content exceeded the labelled amount by 28.6% to 38.7%, and measured purity ranged from 7.7% to 14.4% against the 99% claimed on the labels (Ashraf et al., 2024).
Those purity figures mean the vials were mostly something other than semaglutide by mass, with no peptide-like impurities detected, which points to fillers or counter-ions rather than degradation. The label, the sterility test and even the content assay can all look acceptable while the purity figure is an order of magnitude off. The study covered semaglutide only; no equivalent published test-purchase study exists for tirzepatide, retatrutide or the glucagon dual agonists as of this writing.
Reading a CoA for a Fatty-Acid-Conjugated Peptide
GLP-1-class peptides are harder to verify than a short unmodified peptide because the fatty-acid side chain and its linker are where synthesis most often goes wrong. A certificate should show:
1. Mass spectrometry with the observed mass stated numerically, compared against the theoretical mass for the full conjugate. A peptide missing its side chain or one of the linker units is still a peptide and still produces a plausible HPLC peak, but it is lighter by a fixed, predictable amount. Check the observed mass against a reference source such as PubChem rather than against the supplier's own stated figure.
2. HPLC purity with the chromatogram attached, not only a percentage. Deamidation and oxidation products elute close to the parent peak in a 30-plus-residue peptide, and a purity figure without the trace cannot be checked. The purity-testing guide explains how to read the trace.
3. Net peptide content or a counter-ion statement. Trifluoroacetate and acetate salts, and residual water, routinely account for 10% to 30% of vial mass in lyophilised peptides. A "10 mg" vial at 99% HPLC purity can contain 7 mg of peptide.
4. An endotoxin result if the material will be used in any cell-based or in vivo model. Ashraf's finding of endotoxin in every online sample makes this the test most likely to fail.
5. Batch number matching the vial. A CoA for a different lot does not describe the vial in hand.
The CoA interpretation guide walks through a full certificate section by section.
Handling Notes for Laboratory Use
Fatty-acid-conjugated peptides are more prone to aggregation in solution than short peptides, and albumin-binding chains adsorb to plastic. Lyophilised vials should stay frozen and dark; reconstituted solutions belong at 2 to 8 °C in glass, aliquoted to avoid repeated freeze-thaw. The storage guide and the reconstitution guide cover both in detail, and the degradation pathways guide explains which residues in these sequences are most susceptible.
Frequently Asked Questions
Which compound has the most published evidence? Semaglutide, by a wide margin. It has a completed cardiovascular outcomes trial (SUSTAIN-6), the STEP obesity programme, and years of post-marketing data. Tirzepatide is second. Retatrutide, survodutide and mazdutide have phase 2 data and early phase 3 readouts; CagriSema has one completed phase 3a obesity trial.
Why does retatrutide cost more than semaglutide on the raw platform row but about the same at 10 mg? The retatrutide row includes 20 mg vials and ten-vial kits that lift its median and maximum. At the 10 mg size, the two compounds' medians differ by less than $5.
What do "GLP-1 (S)" and "GLP-3 (R)" mean on a storefront? They are the store's coded names for what it says is semaglutide or retatrutide. The platform lists them as separate rows because the compound cannot be confirmed from the name.
Is a cheaper supplier a worse supplier? The platform has no testing data that would answer that, because no supplier row carries a testing score or CoA link. The Ashraf study found products with acceptable sterility and a plausible label at every price point but with purity between 7.7% and 14.4%. In the published test purchases, price did not predict purity in either direction; a batch-matched CoA is the usable signal.
Can these peptides be compared in the same assay? Semaglutide, tirzepatide and retatrutide all act on the GLP-1 receptor, so a GLP-1 receptor cAMP assay is a shared readout. Tirzepatide and retatrutide additionally need a GIP receptor assay, and retatrutide, survodutide and mazdutide need a glucagon receptor assay, to characterise the full profile. Cagrilintide acts on amylin receptors and needs a separate system.
Is orforglipron a peptide? No. It is a small molecule and is sold as capsules or tablets. Peptide handling guidance does not apply.
References
1. Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021. PMID 33567185
2. Marso SP, et al. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes. N Engl J Med. 2016. PMID 27633186
3. Coskun T, et al. LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of concept. Mol Metab. 2018. PMID 30473097
4. Frías JP, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med. 2021. PMID 34170647
5. Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022. PMID 35658024
6. Franco JV, et al. Tirzepatide for adults living with obesity. Cochrane Database Syst Rev. 2025. PMID 41161687
7. Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med. 2023. PMID 37366315
8. Garvey WT, et al. Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2025. PMID 40544433
9. le Roux CW, et al. Survodutide Once Weekly for the Treatment of Adults with Obesity. N Engl J Med. 2026. PMID 42253238
10. Wharton S, et al. Daily Oral GLP-1 Receptor Agonist Orforglipron for Adults with Obesity. N Engl J Med. 2023. PMID 37351564
11. Ashraf AR, et al. Multifactor Quality and Safety Analysis of Semaglutide Products Sold by Online Sellers Without a Prescription: Market Surveillance, Content Analysis, and Product Purchase Evaluation Study. J Med Internet Res. 2024. PMID 39509151
Research Disclaimer
The compounds described here are supplied to laboratories for research use only. Trial results and trial-arm labels are quoted to identify published findings and do not constitute dosing information. This article does not endorse the purchase or administration of any research chemical for human or veterinary use. Anyone seeking treatment with a GLP-1-class medicine should consult a licensed clinician about approved products.