Peptide Comparison
Pick any three of our 350 encyclopedia entries and see them side by side. Every cell is read from the entries themselves: what kind of molecule it is, where it is approved, how strong the evidence is, its half-life, formula, mass and sport status. Nothing is scored or ranked, and no dose is shown.
| Field | Semaglutide | Tirzepatide | Retatrutide |
|---|---|---|---|
| Encyclopedia entry | Semaglutide Full entry | Tirzepatide Full entry | Retatrutide Full entry |
| Molecule class | Peptide | Peptide | Peptide |
| Category | Metabolic | Metabolic | Metabolic |
| FDA status | FDA Approved | FDA Approved | In Clinical Trials |
| Approved elsewhere | None recorded | None recorded | None recorded |
| Evidence grade | High | High | Medium |
| Half-life | ≈ 7 days | ≈ 5 days | ≈ 6 days |
| Formula | C187H291N45O59 | C225H348N48O68 | Not stated |
| Molecular weight | 4,113.6 g/mol | 4,813.5 g/mol | Not stated |
| WADA 2026 | Not on the 2026 List | Not on the 2026 List | Prohibited (S0 catch-all) |
| WADA 2027 | Not on the 2027 List | Not on the 2027 List | Prohibited (S0 catch-all) |
| In one line | A once-weekly GLP-1 receptor agonist FDA-approved for type 2 diabetes and chronic weight management. | A once-weekly GLP-1/GIP dual agonist that produced unprecedented weight loss in SURMOUNT trials — up to ~21% at highest dose. | An investigational triple hormone agonist that produced ~24% weight loss at 48 weeks in Phase 2 — the largest in any single-agent obesity trial to date. |
| Mechanism | Agonist at the GLP-1 receptor. Enhances glucose-dependent insulin secretion, suppresses inappropriate glucagon, slows gastric emptying, and acts centrally to reduce appetite via hypothalamic and area postrema pathways. Weight loss is driven primarily by the central appetite-suppressing effect rather than the peripheral metabolic actions. | Dual agonist at GIP and GLP-1 receptors. GLP-1 effects include enhanced insulin secretion, reduced glucagon, slowed gastric emptying, and central appetite suppression. GIP contribution is still being characterized but appears to enhance the metabolic effects and may improve GI tolerability compared with GLP-1 monoagonism. Produced greater weight loss than semaglutide in head-to-head SURPASS-2 and SURMOUNT-5 trials. | Triple agonism at GLP-1, GIP, and glucagon receptors. GLP-1 and GIP contribute insulin-sensitization and appetite suppression; glucagon agonism adds thermogenic effects and increased energy expenditure, producing a compound effect on weight loss. The glucagon component requires careful dose titration to avoid hyperglycemia. |
| Sources in the entry | 15 | 10 | 10 |
| Study cards | 8 | 8 | 10 |
| Dosage page | Dosage page | Dosage page | None |
Data: our encyclopedia, rebuilt from the dataset whenever it changes. Grades follow our evidence rubric; sport status is from WADA's 2026 and 2027 Prohibited Lists.
What the comparison shows
Choose any two or three of our encyclopedia entries and the table lines them up field by field. Every cell is read from the entry itself when the page is built, so the comparison cannot say something the entry does not, and it changes whenever an entry is corrected. The rows are the entry's tier (a full entry has been through our evidence review; a short entry has not yet), its molecule class, category, US regulatory status, approvals outside the US, evidence grade, half-life, formula, molecular weight, sport status under the 2026 and 2027 Prohibited Lists, its one-line summary and mechanism, how many sources it cites, how many study cards it carries and whether it has a dosage page.
The URL records your choice, so a comparison can be bookmarked or shared: the tool reads ?a=, ?b= and ?c= with each entry's address.
Reading the rows
FDA status and approvals elsewhere are different questions. Thymosin alpha-1 is approved in dozens of countries and not in the US; semax and selank are registered in Russia. The FDA row says only what the FDA has done.
Molecule class flags what is not a peptide at all. NAD+ is a coenzyme, MK-677 a small molecule and the four monoclonal antibodies are antibodies, and the row says so in words rather than letting their place on a peptide site imply otherwise.
Evidence grade follows our rubric: high needs large human trials or an approval, medium needs published human results, and low means animal or laboratory work, or none. A grade describes the evidence base, not whether a compound works.
Half-life is the entry's own figure, with its source, or the reason there is none, such as "not measured in humans". For compounds whose half-life and time to peak come from a US label, the half-life visualizer draws the curve.
Sport status uses the wording of each entry's Legal table. Its most common value for research peptides is the S0 catch-all: the Prohibited List bans at all times any pharmacological substance not covered elsewhere on the List that has no current approval by any government health authority for human therapeutic use, which covers drugs still in development, discontinued drugs and designer drugs, and it names BPC-157 as an example.1
Why the table has no scores
An earlier version of this tool gave each compound scores out of ten for research, safety, potency, accessibility and cost, drew them as a radar chart, and printed monthly search volumes and PubMed study counts. None of those numbers came from a measurement we could cite, and a chart of invented scores is more persuasive than no chart at all. They were removed in September 2026.
A table can tell you what is known about each compound. It cannot tell you which one works better, because that is a question only a trial that gives both drugs to comparable people can answer. When semaglutide and dulaglutide were compared head to head in type 2 diabetes, 1,201 patients were randomised, and semaglutide lowered HbA1c and body weight more at both dose levels.2 When tirzepatide and semaglutide were compared in 751 adults with obesity, weight fell 20.2% with tirzepatide and 13.7% with semaglutide over 72 weeks.3 For almost every research peptide in the encyclopedia, no such trial exists, and lining up two entries in a table does not create one.
What the comparison cannot do
It does not compare doses, because a dose belongs with its source: an approved drug's label, a trial, or a community figure labelled as one. The dosage pages and the reconstitution calculator carry doses with their sources. It does not compare legality country by country, which our regulatory tracker covers for the compounds it follows. And a short entry carries fewer verified fields than a full one; its row values are the dataset's current record, which the evidence review has not yet reached.
Sources
- World Anti-Doping Agency. The 2026 Prohibited List, section S0 (Non-approved substances). In force January 1, 2026; read in full 2026-09-27. WADA
- Pratley, R. E. et al. (2018). Semaglutide versus dulaglutide once weekly in patients with type 2 diabetes (SUSTAIN 7): a randomised, open-label, phase 3b trial. Lancet Diabetes and Endocrinology, 6(4), 275-286. PMID: 29397376 · doi:10.1016/S2213-8587(18)30024-X
- Aronne, L. J. et al. (2025). Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. New England Journal of Medicine, 393(1), 26-36. PMID: 40353578 · doi:10.1056/NEJMoa2416394
This explainer describes how the tool works and what its numbers rest on. It is not medical advice and does not recommend any dose or product.