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For research use only. Not for human or veterinary use. Not a drug, food, or dietary supplement.
AMIRAVOResearch Library

TB-500 vs GHK-Cu

TB-500 and GHK-Cu are both discussed in tissue-repair research, but they are unrelated molecules with different evidence bases 2,7. TB-500 has been characterised by doping-control laboratories as an N-terminally acetylated seven-amino-acid fragment (Ac-LKKTETQ) of thymosin beta-4 1,2. GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine, which is found in human plasma, saliva and urine 7,8. The FDA lists both among bulk substances for compounding that may present significant safety risks (GHK-Cu for injectable routes), in the nominated-but-withdrawn section of a page current as of 22 April 2026 13.

Unbranded reference vial illustrating TB-500; not an actual product
TB-500
Not approved — research use only
Unbranded reference vial illustrating GHK-Cu; not an actual product
GHK-Cu
Not approved — research use only

Side by side

FieldTB-500GHK-Cu
ClassSynthetic acetylated heptapeptide fragment of thymosin beta-4 1,2Copper-binding tripeptide (metallopeptide complex) 8
Origin and structureAc-LKKTETQ, corresponding to residues 17-23 of the 43-amino-acid protein thymosin beta-4, identified in a product sold as TB-500 1,3Gly-His-Lys, a tripeptide present in human plasma, saliva and urine that binds copper(II) with an affinity similar to albumin's copper transport site 7,8
Proposed mechanismThe LKKTETQ region is the central actin-binding domain of thymosin beta-4 and has been linked in cell and animal work to angiogenesis, cell migration and wound repair 2,3Reviews describe chemoattraction of repair cells, modulation of collagen and glycosaminoglycan synthesis and breakdown, and broad gene-expression effects, largely from cell and animal work 7,8,9
Half-lifeNot located in the sources reviewed for the fragment; in horses, the parent peptide and metabolites were detectable in urine and plasma after administration 2Not located in the sources reviewed
Highest human trial phaseNo published human trial of the fragment located; full-length thymosin beta-4 has reached phase 2 (eye drops) 5No phase-numbered drug trial located; small randomized studies of topical cosmetic products 9,10
FDA statusNot FDA-approved; listed among bulk substances that may present significant safety risks (nomination withdrawn), as of 22 April 2026 13Not FDA-approved; GHK-Cu for injectable routes is listed among bulk substances that may present significant safety risks (nomination withdrawn), as of 22 April 2026 13
Published human outcomesNone for the fragment. Full-length thymosin beta-4 eye drops missed both primary endpoints versus placebo in a 72-person dry-eye trial 5In a 13-patient randomized study after CO2 laser resurfacing, blinded assessment found no difference in erythema or wrinkles; patient-rated satisfaction differed 10
Safety signalsFDA cites immunogenicity and impurity concerns and has not identified human exposure data for the fragment 13FDA cites immunogenicity and impurity concerns for injectable use and notes limited human data 13
WADA statusNamed under S2.3 as thymosin-beta-4 and its derivatives, e.g. TB-500; prohibited at all times (2026 List) 14Not named on the 2026 List; S0 covers unapproved pharmacological substances not addressed elsewhere 14
Who funded the evidenceCharacterisation work came from doping-control laboratories (Ghent University; Hong Kong Jockey Club) 1,2; the full-length eye-drop trial used RegeneRx's RGN-259 5A 2026 systematic review notes that about 35% of the primary literature includes authors from Skin Biology, a company with long-standing commercial interests in GHK-Cu 9

TB-500: what the data says

Published work on TB-500 itself is mostly analytical. A Ghent doping-control laboratory identified Ac-LKKTETQ in a TB-500 product by mass spectrometry 1, and a Hong Kong Jockey Club laboratory developed a method to detect the peptide and its metabolites in horse urine and plasma (animal data) 2. The LKKTETQ sequence is described as the central actin-binding domain of thymosin beta-4, linked in cell and animal studies to angiogenesis, cell migration and wound repair 3.

  • In aged mice (animal data), a synthetic LKKTETQ peptide produced dermal wound-repair changes comparable to the full-length protein 4.
  • No published human study of the fragment was located. Full-length thymosin beta-4 has been studied in humans: an intravenous phase 1 study in 40 healthy volunteers reported no dose-limiting toxicities or serious adverse events 6, and a 72-person phase 2 dry-eye trial missed both primary endpoints while some secondary endpoints differed from placebo 5.

GHK-Cu: what the data says

GHK-Cu has a large preclinical literature and a thin human one 9. Reviews written largely by the Skin Biology group describe effects on collagen, glycosaminoglycans, metalloproteinases and repair-cell recruitment in cell and animal models 7,8.

  • In rabbits (animal data), topical tripeptide-copper complex was associated with smaller unhealed wound areas than no treatment at days 7, 14 and 21 11.
  • In a 72-rat ACL reconstruction model (animal data), GHK-Cu groups showed less knee laxity at 6 weeks than saline, but the difference was not present at 12 weeks 12.
  • In humans, a randomized study of 13 patients after CO2 laser resurfacing found no objective differences in erythema, wrinkles or skin quality, while patient questionnaires favoured the GHK-Cu regimen 10. A 2026 systematic review describes most human trials as small studies of facial cosmetic creams 9.

Key research differences

  • Molecule: TB-500 is a seven-residue acetylated fragment of thymosin beta-4 1, whereas GHK-Cu is a three-residue peptide complexed with copper(II) 8.
  • Endogenous status: GHK occurs naturally in human plasma, saliva and urine 7; Ac-LKKTETQ was characterised as the ingredient of a commercial product, with the acetylation described as artificial 2.
  • Human data: no human study of the TB-500 fragment was located 13, while GHK-Cu has small randomized studies of topical products 9,10.
  • Anti-doping: TB-500 is named under WADA S2.3; GHK-Cu is not named on the 2026 List 14.
  • FDA listing scope: the FDA concern for GHK-Cu is limited to injectable routes, whereas the TB-500 entry is not route-limited and notes no human exposure data 13.

Where the evidence is limited

No study has compared TB-500 and GHK-Cu directly in any model, and their evidence comes from different settings: TB-500 mainly from analytical chemistry and animal studies of the LKKTETQ sequence, GHK-Cu mainly from cell, animal and small topical cosmetic studies 1,4,9. Human data that are often cited for TB-500 actually concern full-length thymosin beta-4, a different molecule given by different routes 5,6. A large share of the GHK-Cu literature comes from one commercially connected research group, which a 2026 systematic review flags as a limitation 9.

Frequently asked questions

Are TB-500 and GHK-Cu related?
No. TB-500 is described as an acetylated fragment (Ac-LKKTETQ) of thymosin beta-4 1, while GHK-Cu is a copper complex of the tripeptide Gly-His-Lys 8.
Has either been tested in human clinical trials?
No published human trial of the TB-500 fragment was located; the FDA states it has not identified human exposure data 13. GHK-Cu has small randomized studies of topical products, such as a 13-patient study after laser resurfacing 10.
Can TB-500 and GHK-Cu be compared directly?
Not on current evidence. No head-to-head study was located, and their data come from different models and routes 4,9,12.
Are they banned in sport?
WADA's 2026 List names TB-500 under S2.3 as a thymosin-beta-4 derivative 14. GHK-Cu is not named on the List 14.

References

  1. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential Drug Testing and Analysis. 2012
  2. Doping control analysis of TB-500, a synthetic version of an active region of thymosin beta-4, in equine urine and plasma by liquid chromatography-mass spectrometry Journal of Chromatography A. 2012
  3. Biological activities of thymosin beta4 defined by active sites in short peptide sequences FASEB Journal. 2010
  4. Thymosin beta 4 and a synthetic peptide containing its actin-binding domain promote dermal wound repair in db/db diabetic mice and in aged mice Wound Repair and Regeneration. 2003
  5. Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE) model Clinical Ophthalmology. 2015
  6. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers Annals of the New York Academy of Sciences. 2010
  7. GHK Peptide as a Natural Modulator of Multiple Cellular Pathways in Skin Regeneration BioMed Research International. 2015
  8. The human tri-peptide GHK and tissue remodeling Journal of Biomaterials Science, Polymer Edition. 2008
  9. A Systematic Review of the Mechanisms and Therapeutic Applications of GHK-Cu (Glycyl-L-Histidyl-L-Lysine-Copper Complex) in Topical Microneedle Delivery: A Case for Expanded Clinical Trials Archives of Internal Medicine Research. 2026
  10. Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin Archives of Facial Plastic Surgery. 2006
  11. Evaluation of the effects of topical tripeptide-copper complex and zinc oxide on open-wound healing in rabbits Veterinary Dermatology. 2006
  12. Tripeptide-copper complex GHK-Cu (II) transiently improved healing outcome in a rat model of ACL reconstruction Journal of Orthopaedic Research. 2015
  13. 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
  14. 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.