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TB-500 Pharmacy

Two liver experiments, opposite interventions, and the TB-500 question.

TB-500 references

The full source list, from actin structure and animal repair experiments to the FDA’s compounding record.

Return to delivery studiesAbout TB-500 Pharmacy

Interventions and tissues

For interventions involving delivery, compare the local cardiac-delivery experiment, then compare the ophthalmic solution with inhaled thymosin beta-4 in rodent lung fibrosis. The intravenous healthy-volunteer study adds a human safety and pharmacokinetic setting. Each uses full-length thymosin beta-4.

Conflicting results

The two liver studies make a useful pair because adding protein and deleting it from a particular cell type both reduced fibrosis in their animal settings. The mouse muscle-function study tests the distance between regenerating fibers and useful strength. The rat stroke dose response shows why the highest amount cannot simply be presumed best.

Chemical identity and regulation

The fragment-characterization paper and equine detection work establish the analytical context for TB-500. The FDA safety-risk page, advisory meeting record and bulk-substance framework address different parts of the pharmacy question. The complete reading list follows.

  1. Irobi E, et al. Structural basis of actin sequestration by thymosin-beta4: implications for WH2 proteins. EMBO J. 2004;23(18):3599-3608. ↗
  2. Bock-Marquette I, et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. ↗
  3. Malinda KM, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999;113(3):364-368. ↗
  4. Morris DC, et al. A dose-response study of thymosin β4 for the treatment of acute stroke. J Neurol Sci. 2014;345(1-2):61-67. ↗
  5. Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther. 2012;12(1):37-51. ↗
  6. Ruff D, et al. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin β4 in healthy volunteers. Ann N Y Acad Sci. 2010;1194:223-229. ↗
  7. Kumar S, et al. Thymosin β4 alleviates renal fibrosis and tubular cell apoptosis through TGF-β pathway inhibition in UUO rat models. BMC Nephrol. 2017;18(1):315. ↗
  8. Sosne G, et al. 0.1% RGN-259 (Thymosin β4) Ophthalmic Solution Promotes Healing and Improves Corneal Integrity. Int J Mol Sci. 2022;24(1):554. ↗
  9. Esposito S, et al. 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 Test Anal. 2012;4(9):733-738. ↗
  10. Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Med. 2026. ↗
  11. Zhu J, et al. Mechanism of thymosin β4 in ameliorating liver fibrosis via the MAPK/NF-κB signaling pathway. J Biochem Mol Toxicol. 2023;37(8):e23338. ↗
  12. Wei Y, et al. Inhaled exogenous thymosin beta 4 suppresses bleomycin-induced pulmonary fibrosis. J Pharm Pharmacol. 2024;76(12):1583-1594. ↗
  13. Kim J, et al. Targeted Deletion of Thymosin Beta 4 in Hepatic Stellate Cells Ameliorates Liver Fibrosis. Cells. 2023;12(12):1658. ↗
  14. Sosne G, et al. Activation of pro-resolving pathways mediate the therapeutic effects of thymosin beta-4. Front Immunol. 2024;15:1458684. ↗
  15. Chen Y, et al. Thymosin β4 released from functionalized self-assembling peptide activates cardiac cells and promotes cardiac repair. Theranostics. 2021;11(10):4790-4808. ↗
  16. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks (list entry: 'Thymosin beta-4, fragment (LKKTETQ), also known as TB-500'; Category 2 from the September 29, 2023 update, now shown as a withdrawn request). ↗
  17. U.S. Food and Drug Administration. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee (agenda lists 'TB-500 (free base)' / 'TB-500 acetate', BPC-157, KPV, and MOTs-C as substances being considered for inclusion on the 503A Bulks List). ↗
  18. U.S. Food and Drug Administration. Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act (Category 1 and Category 2 definitions; 503A/503B bulks-list and nomination framework). ↗
  19. Cha HJ, Jeong MJ, Kleinman HK. Role of thymosin beta4 in tumor metastasis and angiogenesis. J Natl Cancer Inst. 2003. ↗
  20. Zhang Y, et al. Thymosin beta 4 is overexpressed in human pancreatic cancer cells and stimulates proinflammatory cytokine secretion and JNK activation. Cancer Biol Ther. 2008. ↗
  21. Ho EN, et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β4, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A. 2012. ↗
  22. Spurney CF, et al. Evaluation of skeletal and cardiac muscle function after chronic administration of thymosin beta-4 in the dystrophin deficient mouse. PLoS One. 2010. ↗
  23. Delcourt V, et al. TB500/TB1000 and SGF1000: A scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal. 2023. ↗