Repair beyond BPC and TB-500
Thymosin β-4 has 4 phase 3 trials — and they are for dry eye drops, not muscle repair; AHK-Cu has 1 article on PubMed
Experimental material. Read before using anything from here.
Nothing on this page is a medical recommendation, prescription or treatment plan. It is an organized translation of protocols circulating in research communities and, where it exists, of what published trials tested. The two are marked differently — and they are not equivalent.
Most of the compounds here have no FDA approval for human use. Several are sold labeled "research use only", which means they have not gone through purity, sterility or dosage controls for human consumption. A community-reported dose is not a validated dose: it is what someone reported having done.
Talk to a licensed health professional before considering any of these compounds. If you already use one and feel anything unexpected, seek care — do not wait for the next routine test.
Summary
Five lines that repair conversations cite alongside BPC-157 and TB-500 and that hadn't been surveyed here yet: full thymosin β-4 (TB-500 is a fragment of it), AHK-Cu (cousin of GHK-Cu), PE-22-28, PDRN, and growth factors applied to skin. The main finding is about thymosin β-4. It has 1,035 articles and 4 phase 3 trials — the two largest, with 700 and 601 participants, are for an ophthalmic solution for dry eye, sponsored by ReGenTree. The molecule's serious clinical program exists; it just isn't about tendon, muscle, or skin healing.
What these five are, and why they were missing
This site already had the most-discussed repair peptides. The neighbors were missing — and each one is here for a different reason.
Thymosin β-4 is the whole molecule TB-500 comes from, which this site already covers as a fragment. AHK-Cu is the copper peptide cited for hair, alongside GHK-Cu. PE-22-28 shows up in discussions that mix mood and neural repair. PDRN is the fastest-growing aesthetic product in Brazil, and it isn't an exosome — it's a DNA fragment. And isolated growth factors are what the secretome promises to deliver, without the black box of the vesicle.
Two method caveats, before the numbers. The search polydeoxyribonucleotide OR PDRN returns literature for anything carrying the word, and the only phase 3 record it brings up is for defibrotide in hepatic veno-occlusive disease — it comes up because the record uses the term, not because it's the PDRN sold in aesthetics. The search "epidermal growth factor" AND (topical OR skin) is equally broad: the phase 3 records it returns include sunscreen and oral mucositis. Both numbers are a ceiling, and are published as a ceiling.
No number on this page came from the site's secondary source.
How much evidence exists, compound by compound
The numbers below were compiled by me on September 12, 2026, on PubMed and ClinicalTrials.gov. Each row's query is written out in full, next to the number, so anyone can repeat it and contradict me — and so the script that rechecks this site's counts can run all of them.
The condition column is not a claim about mechanism: it's the Condition field copied from the phase 3 records that the search itself returned. When there is no phase 3 record, the cell says so.
| Compound | Condition in phase 3 registrations | Query | Articles in PubMed | Studies on ClinicalTrials.gov |
|---|---|---|---|---|
| Thymosin beta-4 | Dry Eye Syndromes; Dry Eye; Dry Eye Syndrome | "thymosin beta 4" | 1.035 | 18 |
| AHK-Cu | no phase 3 registration in this search | "AHK-Cu" | 1 | 0 |
| PE-22-28 | no phase 3 registration in this search | "PE-22-28" OR spadin | 80 | 0 |
| PDRN | Hepatic Veno-Occlusive Disease | polydeoxyribonucleotide OR PDRN | 4.398 | 18 |
| Topical EGF | Dermatologic Complications; Unspecified Adult Solid Tumor; Protocol Specific; Oral Mucositis | "epidermal growth factor" AND (topical OR skin) | 5.189 | 44 |
What exists in phase 3, and who it belongs to
Article count measures academic attention, not outcome evidence. The table below separates what has a registered phase 3 trial — and shows the largest registration the search returned in each row, with the declared number of participants and the sponsor.
A registration is not a result. A recruiting phase 3 trial is declared intent with money behind it, and nothing more than that.
| Compound | Query | Registered phase 3 trials | The largest registration I opened |
|---|---|---|---|
| Thymosin beta-4 | ("thymosin beta 4") AND AREA[Phase]PHASE3 | 4 | NCT03937882 · n = 700 · ReGenTree, LLC Dry Eye Syndromes, Dry Eye |
| AHK-Cu | ("AHK-Cu") AND AREA[Phase]PHASE3 | 0 | — |
| PE-22-28 | ("PE-22-28" OR spadin) AND AREA[Phase]PHASE3 | 0 | — |
| PDRN | (polydeoxyribonucleotide OR PDRN) AND AREA[Phase]PHASE3 | 1 | NCT00628498 · n = 1,206 · Jazz Pharmaceuticals Hepatic Veno-Occlusive Disease |
| Topical EGF | ("epidermal growth factor" AND (topical OR skin)) AND AREA[Phase]PHASE3 | 6 | NCT01136005 · n = 160 · Impaqtt Foundation Cancer, Skin Rash |
Where the numbers don't add up
- Thymosin β-4's phase 3 is ophthalmic. 4 records, the two largest with 700 and 601 participants, in dry eye syndrome. Whoever cites “thymosin β-4 has a phase 3 trial” to justify tendon application is using a true fact to answer a different question.
- AHK-Cu practically doesn't exist in the literature. 1 article with the spelling in quotes, 0 registered studies. GHK-Cu, which this site already covers, is a different order of magnitude — and even it doesn't support what the marketing says.
- PE-22-28: 80 articles and 0 registered studies. Small literature and no registered clinical translation. The search includes the synonym
spadinprecisely so as not to underestimate. - PDRN has 4,398 articles and 18 registered studies. The gap between the two numbers is the point: the word is old in the literature, and the injectable aesthetic product is recent and has barely entered trial registration.
In Brazil
I searched every active ingredient in the open data on registered medicines, downloaded on September 12, 2026 — 43,508 rows, counting only Active status.
The three searches come back empty. For PDRN this matters more than it seems: the product circulates in Brazilian aesthetic clinics, and its absence here means there's no registered medication with that active ingredient. The same reasoning from the exosomes page applies — an aesthetic product intended for an injectable procedure doesn't get regularized as a cosmetic.
| Active ingredient | Search pattern | Active registrations | Declared therapeutic class | Products |
|---|---|---|---|---|
| Thymosin | TIMOSINA | 0 | — | — |
| PDRN | POLIDESOXIRRIBONUCLEOT | 0 | — | — |
| Epidermal growth factor | FATOR DE CRESCIMENTO EPID | 0 | — | — |
References
- Public ClinicalTrials.gov API, version 2 — the source for all the study and phase 3 counts on this page.
- PubMed E-utilities (esearch) — the basis for all article counts on this page.
- Registration NCT03937882 on ClinicalTrials.gov — RGN-259, an ophthalmic solution of thymosin β-4, 700 participants, sponsored by ReGenTree.
- Registration NCT00628498 on ClinicalTrials.gov — defibrotide in hepatic veno-occlusive disease, the only phase 3 record that the search for polydeoxyribonucleotide returns.