Peptilex – The Peptide Encyclopedia
- 34 peptides – from semaglutide to BPC-157 – in one book
- An evidence grade (A–E) and the key studies for every peptide
- Where each one stands in 2026 – US, EU and Switzerland
Evidence, explained
How strong is the research behind each peptide? Grades, trial phases and the key results – as charts.
The evidence grades
One grade per peptide for its main use – the same scale as in the books. The grade describes how far the research has come, not the substance.
- AA – Approved medicine, large randomized trials
- BB – Randomized human trials
- CC – Small or early human studies
- DD – Mainly animal studies
- EE – Mainly cell studies
Evidence grades for all 34 peptides
AApproved medicine, large randomized trials
BRandomized human trials
CSmall or early human studies
DMainly animal studies
EMainly cell studies
Source: Peptilex evidence grades A–E (Peptilex 1, Appendix A; tracked peptides: weekly review)
From lab to approval
- LabCells and molecules: is the mechanism plausible?
- AnimalEffects in a living organism.
- Phase 1First tests in people: safety and tolerability.
- Phase 2Does it work? First signals of benefit.
- Phase 3Large randomized trials that confirm the benefit.
- ApprovalRegulators review all data.
ongoing / startingcompleted / other
Phase 1229
Phase 2278
Phase 3346
Phase 4226
Other296
Source: PubMed and ClinicalTrials.gov via the Peptilex study database
58
482017
45
842019
47
802021
86
1052023
126
1332025
157
122027
Source: PubMed and ClinicalTrials.gov via the Peptilex study database
Key results as charts
TreatmentPlacebo
RetatrutideTRIUMPH-1 · 80 wk¹
25.0%
3.9%
TirzepatideSURMOUNT-1 · 72 wk¹
20.9%
3.1%
CagriSemaREDEFINE 1 · 68 wk
20.4%
3.0%
SemaglutideSTEP 1 · 68 wk
14.9%
2.4%
¹ Highest-level treatment group. Different trials, durations and populations – not a head-to-head comparison.
Sources: TRIUMPH-1 · NEJM 2026 · SURMOUNT-1 · NEJM 2022 · REDEFINE 1 · NEJM 2025 · STEP 1 · NEJM 2021
| Average weight loss in landmark trials | Trial | Treatment | Placebo |
|---|---|---|---|
| Retatrutide | TRIUMPH-1 | 25.0% | 3.9% |
| Tirzepatide | SURMOUNT-1 | 20.9% | 3.1% |
| CagriSema | REDEFINE 1 | 20.4% | 3.0% |
| Semaglutide | STEP 1 | 14.9% | 2.4% |
TreatmentSemaglutide
TirzepatideSURMOUNT-5 · 72 wk
20.2%
13.7%
CagriSemaREDEFINE 5 · 2026
18.4%
11.9%
Sources: SURMOUNT-5 · NEJM 2025 · REDEFINE 5 · 2026
20%fewer heart attacks, strokes or cardiovascular deathsSELECT · 17,604 people · NEJM 2023
24%fewer major kidney eventsFLOW · 3,533 people · NEJM 2024
Sources: SELECT · NEJM 2023 · FLOW · NEJM 2024 · ESSENCE · NEJM 2025
Thymosin beta-4 eye drops
6 of 10
Placebo
1 of 8
Source: SEER-1 · Int J Mol Sci 2022 · 18 participants
TreatmentComparison
GHK-Cu gelMedian wound closure · Mulder et al.
98.5%
60.8%
Thymosin alpha-1Complete response, chronic hepatitis B · Chien et al.
40.6%
9.4%
Sources: Mulder et al. · Wound Repair Regen 1994 · Chien et al. · Hepatology 1998
Study labels
Meta-analysisSystematic reviewHuman RCTClinical trialHuman studyCase reportAnimal studyLab studyRegistered trialApproved medicine
Glossary
- Accelerated approval
- A US pathway that allows approval based on a measure reasonably likely to predict benefit, with confirmatory trials required afterwards.
- Agonist
- A substance that activates a receptor.
- Amino acid
- The basic building block of peptides and proteins.
- AMPK
- An enzyme that acts as the cell's energy sensor.
- Analogue
- A modified version of a natural substance.
- Angiogenesis
- The formation of new blood vessels.
- Bioavailability
- The share of a substance that reaches the bloodstream and its target.
- Blinding
- Keeping participants and/or researchers unaware of who receives the real treatment, to avoid bias.
- Evidence grade
- The Peptilex rating from A to E describing how strong the evidence for a use is.
- GHRH
- Growth hormone–releasing hormone, the hypothalamic signal that stimulates growth hormone release.
- GHRP
- Growth hormone–releasing peptide, a synthetic peptide acting on the ghrelin receptor.
- GLP-1
- Glucagon-like peptide-1, a gut hormone that boosts insulin release and promotes fullness.
- IGF-1
- Insulin-like growth factor 1, a hormone produced mainly in the liver in response to growth hormone.
- Immunogenicity
- The ability of a substance to provoke an immune response.
- In vitro / in vivo
- In the laboratory (cells, test tubes) / in a living organism.
- Meta-analysis
- A statistical combination of the results of several studies.
- Off-label
- Use of an approved medicine for a purpose, group or form not covered by its approval.
- Peptide
- A short chain of amino acids, roughly 2 to 50.
- Phase 1, 2, 3
- Stages of clinical trials, from first safety testing in small groups to large confirmatory trials.
- Placebo
- An inactive comparison treatment.
- Randomized controlled trial (RCT)
- A study in which participants are assigned by chance to treatment or comparison groups.
- Receptor
- A protein on or in a cell that recognizes a specific signal.
- Secretagogue
- A substance that causes another substance to be released.
- Surrogate marker
- A measurement (such as a blood value) used in place of a real health outcome.
- Telomeres
- Protective caps at the ends of chromosomes.
Go deeper
All 34 peptides in one book
Every profile: what it is, the key studies, the evidence grade and where it stands in 2026.
Coming soonPeptilex – The Honest GLP-1 HandbookSemaglutide, tirzepatide and the new pills, explained for adults over 50.