Comparison
BPC-157 vs TB-500
Two research compounds discussed interchangeably for tissue repair. Their mechanisms, their evidence bases and their regulatory positions are not the same.
Comparison
Semaglutide vs Tirzepatide vs Retatrutide
These three compounds represent successive generations of incretin pharmacology: one receptor, then two, then three. They are frequently compared on a single number — average weight reduction — which is the least informative way to read them. Two are approved medicines with labels and warnings; one is investigational and not available outside clinical trials. That distinction matters more than any percentage.
Side by side
Every row is traceable to the linked compound profile. Note that this table has no “best for” row: framing investigational compounds that way reads as a treatment recommendation, so we compare primary areas of research instead.
| Attribute | SemaglutideFDA approved | TirzepatideFDA approved | RetatrutideNot FDA approved |
|---|---|---|---|
| Receptor targets | GLP-1 | GIP and GLP-1 | GIP, GLP-1 and glucagon |
| Regulatory status | FDA Approved | FDA Approved | Investigational |
| Overall evidence level | CLINICAL | CLINICAL | CLINICAL |
| Approved indications | Type 2 diabetes; chronic weight management; cardiovascular risk reduction in adults with established CVD and obesity or overweight; noncirrhotic MASH with F2–F3 fibrosis | Type 2 diabetes; chronic weight management; moderate to severe obstructive sleep apnoea in adults with obesity | None — not approved for any indication |
| Pivotal weight-reduction figures | STEP 1: substantial mean reduction vs placebo at 68 weeks | SURMOUNT-1: approximately 16.0%–22.5% at 72 weeks by dose | TRIUMPH-1 (sponsor-reported): 19.0%, 25.9%, 28.3% at 80 weeks by dose; 30.3% at 104 weeks on 12 mg |
| Cardiovascular outcomes evidence | SELECT: reduction in major adverse cardiovascular events in a secondary-prevention population | Less mature than semaglutide; check current labelling | None |
| Boxed warning | Yes — risk of thyroid C-cell tumours | Yes — risk of thyroid C-cell tumours | No label exists, so no labelled warnings exist |
| Availability | By prescription, as approved products | By prescription, as approved products | Clinical trials only |
| Principal open question | Long-term outcomes over decades of continuous use | The precise contribution of GIP agonism, and cardiovascular outcome data | Whether the efficacy survives regulatory review, and the tolerability profile at the highest dose |
What adding receptors is meant to achieve
GLP-1 receptor agonism enhances glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying and reduces appetite. This is the foundation.
GIP receptor agonism, added by tirzepatide, contributes further insulinotropic effect and appears to act on adipose tissue and central appetite circuits. Its precise contribution is still being characterised — a reminder that clinical effect can be demonstrated before mechanism is fully understood.
Glucagon receptor agonism, added by retatrutide, increases energy expenditure and promotes hepatic fat oxidation. On its own it would raise blood glucose; the design relies on the two incretin components to offset that.
Why comparing weight figures across trials is a trap
The numbers in the table come from different trials, run at different times, in different populations, over different durations, against different placebo arms. Cross-trial comparison is a well-known way to reach a confident wrong answer.
Only head-to-head randomised trials settle these questions directly, and there is no head-to-head trial of all three.
The distinction that actually matters
Semaglutide and tirzepatide are medicines. They have labels specifying who they are for, what they are not for, what the warnings are, and which interactions to watch. A prescriber and a pharmacist stand between the patient and the drug.
Retatrutide has none of that. It has a strong efficacy signal, an incomplete safety picture, and no regulatory review. Its tolerability data include a dose-dependent rise in discontinuation for adverse events, reaching 11.3% at the highest dose against 4.9% on placebo — the kind of detail that survives in a regulatory review and evaporates in a headline.
The indications diverge more than the mechanisms
The most useful difference between semaglutide and tirzepatide is not how much weight people lost. It is what else each has been shown to do.
Semaglutide holds an indication for cardiovascular risk reduction, earned in a dedicated outcomes trial, and one for MASH with moderate to advanced fibrosis. Tirzepatide holds the first-ever drug approval for obstructive sleep apnoea in adults with obesity, earned with sleep-study endpoints.
Those are different clinical propositions, resting on different trials, and neither is captured by a weight-loss percentage.
Frequently asked questions
Which produces the most weight loss?
Reported mean reductions are highest for retatrutide, but the comparison is across separate trials rather than head-to-head, and retatrutide is not approved. Cross-trial comparisons of this kind are unreliable.
Can I get retatrutide?
Only by participating in a clinical trial. It has no marketing authorisation. Material sold online under the name is not the investigational product and carries no verification of identity, purity or potency.
Do all three have the same side effects?
Gastrointestinal effects — nausea, diarrhoea, vomiting, constipation — are common across the class and dose-related. The approved drugs carry boxed warnings for thyroid C-cell tumour findings in rodents. Retatrutide has no label yet, so no regulator-reviewed warnings exist for it.
Other comparisons
Comparison
CJC-1295 vs Ipamorelin
Two growth hormone secretagogues with different receptors and very different evidence. One has Phase 1 hormone data; the other has a published Phase 2 trial that missed its endpoint.
Comparison
Tesamorelin vs CJC-1295
Two GHRH analogs with the same upstream mechanism and completely different evidence. What separates an approved medicine from a discontinued research compound.
References
Peptide Insider cites primary sources wherever they exist — regulatory documents, trial registrations and peer-reviewed literature — in preference to secondary summaries.
- 1.U.S. Food and Drug Administration. WEGOVY (semaglutide) — Highlights of Prescribing Information. FDA Drugs@FDA, 2026;NDA 215256, label revised 02/2026.Regulatory
- 2.U.S. Food and Drug Administration. ZEPBOUND (tirzepatide) — Highlights of Prescribing Information. FDA Drugs@FDA, 2026;NDA 217806, label revised 01/2026.Regulatory
- 3.Jastreboff AM, Aronne LJ, Ahmad NN, et al.. Tirzepatide once weekly for the treatment of obesity. The New England Journal of Medicine, 2022;387(3):205–216.
- 4.Eli Lilly and Company. Lilly’s triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial. Eli Lilly investor news release, 2026;Published 21 May 2026.InstitutionNCT05929066