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AMIRAVOResearch Library

B7-33 vs BPC-157

B7-33 and BPC-157 are both short peptides studied in tissue-injury models, but they come from different parent molecules and differ in how clearly their target is defined 1,10. B7-33 is a single-chain analogue of the B chain of human gene-2 relaxin, designed as a functionally selective agonist of the relaxin receptor RXFP1 that favours ERK signalling over cAMP 1,2. BPC-157 is a synthetic 15-amino-acid partial sequence of a protein isolated from human gastric juice, with no single identified receptor 8,10. Neither has been studied in a registered human trial with posted results, and BPC-157 appears on the FDA's compounding page of substances that may present significant safety risks, current as of 22 April 2026 6,11,12.

Unbranded reference vial illustrating B7-33; not an actual product
B7-33
Not approved — research use only
Unbranded reference vial illustrating BPC-157; not an actual product
BPC-157
Not approved — research use only

Side by side

FieldB7-33BPC-157
ClassSingle-chain relaxin B-chain analogue; functionally selective RXFP1 agonist 1,2Synthetic pentadecapeptide (15 amino acids) 10
Origin and structureDerived from the B chain of human gene-2 relaxin, designed to avoid the complex two-chain, disulfide-rich structure of the hormone 1,2Partial sequence of 'body protection compound' isolated from human gastric juice 10
Proposed mechanismBinds RXFP1 and preferentially activates ERK1/2 over cAMP; anti-fibrotic effects were linked to RXFP1-angiotensin II type 2 receptor heterodimers and MMP-2 (cell and rodent data) 1Preclinical work suggests growth hormone receptor up-regulation, angiogenesis pathways and reduced inflammatory cytokines 8; FAK-paxillin activation in rat tendon fibroblasts 10
Half-lifeNot located in the sources reviewedUnder 30 minutes, from rat and dog pharmacokinetic work cited in a systematic review; no human data 8
Highest human trial phaseNo registered study located (ClinicalTrials.gov searched 24 October 2026) 6Phase 1 registration in healthy volunteers, status unknown, no results posted 11
FDA statusNot FDA-approved and not named on the FDA compounding page as of 22 April 2026 12. Recombinant relaxin-2 (serelaxin) also has no Drugs@FDA record (searched 24 October 2026) 7Not FDA-approved 8; listed among bulk substances that may present significant safety risks (nomination withdrawn), as of 22 April 2026 12
Published human outcomesNone located 6Three small uncontrolled reports (30 people in total) described symptom improvement; certainty rated very low 9
Safety signalsNot located for humans; the design rationale notes that strong cAMP activation by relaxin has been linked to tumour-promoting actions, which the ERK-biased analogue was intended to avoid (cell and animal reasoning) 1No clinical safety data found in one systematic review 8; FDA cites immunogenicity and impurity concerns and limited safety information 12
WADA statusNot named on the 2026 List; S0 covers unapproved pharmacological substances not addressed elsewhere 13Named under S0 (non-approved substances); prohibited at all times (2026 List) 13
Who funded the evidenceAcademic groups: the Florey Institute and University of Melbourne designed the peptide 1,2; later cardiac work came from Virginia Commonwealth University with US NIH support and from Monash University 4,5Cell studies from Chang Gung University 10; human reports from private clinics, summarised in systematic reviews 8,9

B7-33: what the data says

B7-33 was designed to reproduce relaxin's anti-fibrotic actions with a simpler structure. In cells that express RXFP1 and in three rodent models of heart or lung disease (cell and animal data), it prevented or reversed fibrosis and dysfunction with potency similar to H2 relaxin 1.

  • In rats and in mouse arteries ex vivo (animal data), B7-33 reproduced relaxin's acute vascular effects and prevented endothelial dysfunction induced by placental trophoblast conditioned media 3.
  • In mice after ischemia-reperfusion injury (animal data), B7-33 reduced infarct size and preserved fractional shortening compared with vehicle 4.
  • In a mouse cardiomyopathy model (animal data), B7-33 reduced left ventricular fibrosis and inflammation, and the comparison drug perindopril lowered blood pressure but not fibrosis 5.
  • No registered human study was located 6.

BPC-157: what the data says

A systematic review of 36 BPC-157 studies found 35 preclinical studies and one clinical study 8. In rat tendon-fibroblast cultures (cell data), BPC-157 increased explant outgrowth, survival under oxidative stress and cell migration 10.

  • In animal injury models, the review reports improved functional, structural and biomechanical outcomes in muscle, tendon, ligament and bone (animal data only) 8.
  • Human data are limited to three small uncontrolled reports, which a 2026 systematic review judged poor quality with very low certainty 9.
  • A phase 1 safety and pharmacokinetics trial was registered in 2015, but its status is unknown and no results are posted 11.

Key research differences

  • Target definition: B7-33 has a defined receptor, RXFP1, with signalling bias documented in cells 1, while BPC-157's proposed mechanisms span several pathways without a single identified receptor 8.
  • Human data: BPC-157 has three small uncontrolled human reports 9; no human study of B7-33 was located 6.
  • Anti-doping: BPC-157 is named under WADA S0, whereas B7-33 is not named on the 2026 List 13.
  • FDA compounding listing: BPC-157 appears on the FDA's significant-safety-risk page; B7-33 does not 12.
  • Preclinical focus: B7-33's animal work is cardiac, vascular and anti-fibrotic 1,4,5; BPC-157's is musculoskeletal and gastrointestinal healing 8.

Where the evidence is limited

No study has compared B7-33 and BPC-157. B7-33's evidence is entirely cell and rodent work from a small number of academic groups, with no human study located, so nothing is known about its behaviour in people 1,6. BPC-157's human evidence consists of three uncontrolled reports rated very low certainty, and its own systematic reviews describe the literature as overwhelmingly preclinical 8,9. The two compounds were studied in different organ systems and endpoints, so their animal findings are not comparable 1,8.

Frequently asked questions

What is B7-33 derived from?
It is a single-chain analogue of the B chain of human gene-2 relaxin, designed as a functionally selective RXFP1 agonist that favours ERK signalling over cAMP 1,2.
Has either peptide been tested in humans?
No registered human study of B7-33 was located 6. BPC-157 has three small uncontrolled human reports and one phase 1 registration without posted results 9,11.
Can B7-33 and BPC-157 be compared directly?
No. No head-to-head study was located, and their preclinical work addresses different organ systems 1,8.
Are they named by regulators or anti-doping authorities?
BPC-157 is on the FDA's compounding page of substances that may present significant safety risks and is named under WADA S0 12,13. B7-33 is not named in either source 12,13.

References

  1. A single-chain derivative of the relaxin hormone is a functionally selective agonist of the G protein-coupled receptor, RXFP1 Chemical Science. 2016
  2. Single chain peptide agonists of relaxin receptors Molecular and Cellular Endocrinology. 2019
  3. B7-33 replicates the vasoprotective functions of human relaxin-2 (serelaxin) European Journal of Pharmacology. 2017
  4. B7-33, a Functionally Selective Relaxin Receptor 1 Agonist, Attenuates Myocardial Infarction-Related Adverse Cardiac Remodeling in Mice Journal of the American Heart Association. 2020
  5. The single-chain relaxin mimetic, B7-33, maintains the cardioprotective effects of relaxin and more rapidly reduces left ventricular fibrosis compared to perindopril in an experimental model of cardiomyopathy Biomedicine & Pharmacotherapy. 2023
  6. ClinicalTrials.gov API search for B7-33 (0 studies returned, 24 October 2026) ClinicalTrials.gov. 2026
  7. Drugs@FDA (openFDA) query for active ingredient serelaxin: no matches FDA openFDA. 2026
  8. Emerging Use of BPC-157 in Orthopaedic Sports Medicine: A Systematic Review HSS Journal. 2025
  9. Human evidence for BPC-157 in orthopaedic and regenerative medicine: a systematic review of efficacy and safety Acta Orthopaedica Belgica. 2026
  10. The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration Journal of Applied Physiology. 2011
  11. PCO-02 - Safety and Pharmacokinetics Trial (NCT02637284) ClinicalTrials.gov. 2015
  12. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (content current as of 04/22/2026) FDA (Human Drug Compounding). 2026
  13. Prohibited List 2026 (in force 1 January 2026) World Anti-Doping Agency. 2026

For research use only. Not for human or veterinary use. Not a drug, food, or dietary supplement. This page compares published research and is not medical advice or a recommendation.