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AMIRAVOResearch Library
Cycle-length evidence

TB-500 cycle length: what human studies ran

Not approved — research use onlyCPreclinical research
Short answer: there is no established TB-500 cycle length or break. The human studies below ran for set periods under monitoring; none tested repeated courses.

Treatment and follow-up in human studies

  1. The intravenous phase 1 study in healthy volunteers gave a single dose and then repeated administration over 14 days 11.
  2. The controlled adverse environment dry eye trial treated participants for 28 days across six visits over a 32-day period; the severe dry eye phase 2 trial treated for 28 days with assessment continuing to day 56 12.
  3. The neurotrophic keratopathy phase 3 trial assessed healing after 4 weeks of treatment and again at day 43, two weeks after treatment stopped 15.
  4. The venous stasis ulcer and pressure ulcer registry records describe topical application for up to 84 days 16.
  5. The STEMI trials administered recombinant human thymosin beta 4 for 7 days starting after PCI, with imaging follow-up at 90 days 18.

What has not been tested

  • On-and-off schedules or breaks between courses.
  • Repeated courses and long-term exposure beyond the periods listed.
  • TB-500 combined with other compounds, unless a study above says so.

Frequently asked questions

Is there an established TB-500 cycle length?
No. Human studies administered TB-500 for the periods listed on this page. Those are study durations; none tested an on-and-off schedule or a break.
What is the longest human study of TB-500?
The durations are listed on this page with their sources; compare them directly rather than relying on a summary.
Do study durations tell me how long to use something?
No. A study duration is how long investigators administered a compound to selected participants under monitoring. It is not a recommended course, and a break between courses has not been tested for any compound on this site that is not approved.
TB-500 dosing reference Full research page

References

  1. beta-Thymosins Ann N Y Acad Sci. 2007
  2. Thymosin β4 and the vasculature: multiple roles in development, repair and protection against disease Expert Opin Biol Ther. 2018
  3. FDA Briefing Document: TB-500-Related Bulk Drug Substances (TB-500 free base and TB-500 acetate), Pharmacy Compounding Advisory Committee, July 23-24, 2026 FDA. 2026
  4. 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
  5. Doping control analysis of TB-500, a synthetic version of an active region of thymosin beta4, in equine urine and plasma by liquid chromatography-mass spectrometry J Chromatogr A. 2012
  6. 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 Regen. 2003
  7. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (page content current as of 04/22/2026) FDA. 2026
  8. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the FD&C Act (categories 1, 2 and 3; updated May 14, 2026) FDA. 2026
  9. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee (agenda, questions and briefing documents) FDA Advisory Committee Calendar. 2026
  10. International Standard: Prohibited List 2026 (S0 Non-approved substances; S2 Peptide hormones, growth factors, related substances and mimetics) World Anti-Doping Agency. 2026
  11. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers Ann N Y Acad Sci. 2010
  12. Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE) model Clin Ophthalmol. 2015
  13. Thymosin beta4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial Cornea. 2015
  14. FDA Advisory Committee Voted Yes on Six Peptides. Now What? The Regulatory Road Ahead (law-firm commentary; secondary source) (summary of FDA advisory committee proceedings) US Food and Drug Administration. 2026
  15. 0.1% RGN-259 (Thymosin ss4) Ophthalmic Solution Promotes Healing and Improves Comfort in Neurotrophic Keratopathy Patients in a Randomized, Placebo-Controlled, Double-Masked Phase III Clinical Trial Int J Mol Sci. 2022
  16. The effect of thymosin treatment of venous ulcers (phase 2 dose-escalation study; registry record NCT00832091) Ann N Y Acad Sci. 2010
  17. Study of Thymosin Beta 4 in Patients With Pressure Ulcers (NCT00382174), phase 2 registry record with posted results ClinicalTrials.gov. 2008
  18. Recombinant human thymosin beta 4 improves ischemic cardiac dysfunction in mice and patients with acute ST-segment elevation myocardial infarction after reperfusion Cardiovasc Res. 2025
  19. A Phase 1a Study of Thymosin Beta 4 in Healthy Volunteers (NCT04555824), completed registry record ClinicalTrials.gov. 2018
  20. Safety and Efficacy Study of Thymosin Beta 4 in Patients With Acute Myocardial Infarction (NCT05485818), completed phase 2 registry record ClinicalTrials.gov. 2021
  21. Evaluation of the Safety and Efficacy Study of RGN-137 Topical Gel for Junctional and Dystrophic Epidermolysis Bullosa (NCT03578029), terminated phase 2 registry record ClinicalTrials.gov. 2021
  22. Assessment of the Safety and Efficacy of RGN-259 Ophthalmic Solutions for Dry Eye Syndrome: ARISE-3 (NCT03937882), completed phase 3 registry record with posted results ClinicalTrials.gov. 2021
  23. Assessment of the Safety and Efficacy Study of RGN-259 Ophthalmic Solutions for Neurotrophic Keratopathy: SEER-1 (NCT02600429), terminated phase 3 registry record with posted results ClinicalTrials.gov. 2020
  24. Comparative Study of Thymosin Beta 4 Eye Drops vs. Vehicle in the Treatment of Severe Dry Eye (NCT01393132), completed phase 2 registry record ClinicalTrials.gov. 2013