Pinc PeptideThe girly peptide research blog

TB-500 · Dose evidence · updated 8 October 2026

TB-500 dosage: what studies actually used

The short answer

FDA’s 2026 review found no study that gave TB-500 to people by any route, and a PubMed search on 8 October 2026 found none either, so there is no human dose to report1213. FDA also found no human data on how the body absorbs or clears it12. Human trials of full-length thymosin beta-4, a different and much larger molecule, used eye drops, skin gels and IV doses, and those doses do not apply to TB-5001371214.

Not dosing advice. This page reports doses that studies and approved labels used, with their sources. It does not recommend a dose, and we do not give mixing, injection or unit-conversion instructions. Gray-market vials often do not contain what their label says. How we report doses.

Studies, animals and users: kept apart

Doses below are what studies used or what a label says. They are not advice, and gray-market products may not contain what their label says.

In human studies

No dose of TB-500 has been studied in humans by any route, and FDA found no human pharmacokinetic data12. Doses from trials of full-length thymosin beta-4, such as eye drops used four times a day, are for a different molecule and do not apply14.

In animal studies

Rats (Achilles tendon repair): 60 µg/kg/day by intraperitoneal injection for four weeks, alone or with BPC-157 at 10 µg/kg/day, 8 rats per group16. Aged mice (skin wounds): 50 µL of a 0.01% solution of the non-acetylated fragment applied to each wound on the day of wounding and 48 hours later12. Pharmacokinetic studies only: a single 10 mg subcutaneous dose in horses, and 50 mg/kg by intraperitoneal injection in rats12. Cultured cells: 50 µg/mL had no effect on scratch-wound closure1217.

What users report Anecdotal · not validated · not a recommendation

One dosing-chart site lists 500 to 1,000 µg by injection under the skin once a day. The same page says this schedule is not a regimen established by human TB-500 research15.

Half-life and how it is taken

Half-life
No human value found12FDA found no human exposure data for TB-500 by any route12. In horses given 10 mg under the skin, blood levels peaked at 0.05 to 0.08 ng/mL between 1 and 2 hours after the dose and could no longer be measured 6 to 10 hours after it. FDA’s review gives no half-life value.
Routes
  • Subcutaneous injection (the usual community route; no human data found; the only drug-level data we found are from horses)
  • Intramuscular injection (proposed in the withdrawn compounding nomination; no human data or animal drug-level data found)
  • Intraperitoneal injection (rats only)
  • Nasal spray (sold in blends with BPC-157; no data found)
  • Topical (only the non-acetylated fragment, in mice)

TB-500 is not thymosin beta-4

FDA defines TB-500 as a 7-amino-acid fragment of thymosin beta-4 (positions 17 to 23) with an acetyl cap, while thymosin beta-4 is the full 43-amino-acid protein, and FDA says the two ‘are not the same substance’12. Sellers still blur them: of the 200 most recent samples in Finnrick’s TB-500 test log (January to September 2026), 68 had product names containing ‘TB-500 (Thymosin Beta-4)’18.

FDA says even the same fragment without its acetyl cap cannot be assumed to act like TB-5001219. Doses from thymosin beta-4 trials therefore describe a different drug, given in different ways1214.

Doses used in thymosin beta-4 trials (not TB-500)

None of these trials of full-length thymosin beta-4, listed largest first, tested TB-500 or gave the drug as an injection under the skin12345678910111214. The thymosin beta-4 dose page sets out every one of them.

  • ARISE-3, Phase 3 (700 adults with dry eye): 0.1% eye drops four times a day for 14 days. Its maker said it did not meet its main goals, and the results posted on 28 August 2026 show similar average changes on the drops and on placebo1420.
  • ARISE-2 (601 adults with dry eye): 0.1% eye drops four times a day for 28 days; at day 29, discomfort was up 0.07 points on the drops and down 0.04 on placebo (0 to 5 scale), with no statistical test posted; the company reported less discomfort at day 15 (p = 0.0149) but said the trial did not duplicate the results of an earlier trial, ARISE-1121.
  • Venous leg ulcers (72 adults in the registry, 73 in the published paper): 0.01%, 0.03% or 0.1% gel once a day for up to 84 days; by day 84, ulcers had closed in 12 of 55 people on gel (22%) and 4 of 17 on placebo (24%), a secondary measure (the main one was safety); the authors still said the 0.03% strength ‘may have the potential to accelerate wound healing’34.
  • Pressure ulcers (72 adults): 0.01%, 0.02% or 0.1% gel once a day for up to 84 days; ulcers healed in 8 of 54 people on gel (15%) and 3 of 18 on placebo (17%), a secondary measure (the main one was safety)5.
  • Dry eye tested in a controlled-environment chamber (72 adults): 0.1% eye drops twice a day for 28 days; the main measures were not significantly better than placebo2.
  • Heart attack (62 patients after a procedure to reopen a blocked heart artery): 0.25, 0.5 or 2.0 µg/kg by IV injection once a day for 7 days, with 90 days of follow-up; the trial was completed in November 2021, and no results have been posted6.
  • Healthy volunteers (40 adults in four groups of 10, each group given one dose level or placebo): 42, 140, 420 or 1,260 mg given IV, as one dose and then daily for 14 days; there was no dose-limiting toxicity and no serious adverse event7.
  • Epidermolysis bullosa, a group of mostly inherited blistering skin diseases (30 people): 0.01%, 0.03% or 0.1% gel once a day for up to 56 days; the trial was stopped early for lack of patients and because the study drug expired, and wounds healed in 8 of 22 people on gel and 5 of 8 on placebo, a difference that was not statistically significant8.
  • Neurotrophic keratopathy, a nerve-damage disease of the cornea (SEER-1, 18 people): 0.1% eye drops five times a day for 4 weeks; at the end of treatment the defect had healed completely in 6 of 10 on drops and 1 of 8 on placebo, a difference short of statistical significance (p = 0.0656), and two weeks after treatment ended in 5 of 10 and 0 of 8 (p = 0.0359)910.
  • Severe dry eye (9 people): 0.1% eye drops six times a day for 28 days; by day 56, discomfort and surface damage had improved more than with the plain drops11.

Why there is no established dose

FDA found no human data on how TB-500 is absorbed or cleared, and no animal toxicity studies of any kind12. Daily dosing has been studied only in animals, such as a 2026 rat study of Achilles tendon repair that its authors called exploratory and that describes its peptide as ‘synthetic thymosin beta-4 (TB-500)’16.

The only ClinicalTrials.gov record found that names TB-500 calls itself ‘fictional’ in its own summary22. Vial contents are also unreliable: 113 of Finnrick’s latest 200 TB-500 tests (January to September 2026) failed its strict standard of at least 99.5% purity and an amount within 35% of the label, and FDA has found different salts and even different active molecules sold under the TB-500 name1218.

Questions people ask

How much TB-500 should I take?

No dose of TB-500 is established: FDA found no study that tested it in people by any route, and neither did our PubMed search1213. Thymosin beta-4 trials used eye drops, skin gels and IV doses of a different molecule, so their doses do not carry over1214. TB-500 is not an approved drug, and US pharmacies may not compound it1223.

Can I take TB 500 every day?

FDA found no study that tested TB-500 in people at all, daily or otherwise, so whether everyday use is safe is unknown12. FDA also found no animal toxicity studies of any kind, and daily dosing has been studied only in animals, such as a 4-week rat study of tendon repair1216. Daily doses in thymosin beta-4 trials, such as eye drops four times a day or IV doses for 14 days, were of a different molecule1712.

Is thymosin beta-4 dosing the same as TB-500 dosing?

No: TB-500 is a 7-amino-acid fragment of the 43-amino-acid thymosin beta-4, and FDA says the two are not the same substance12. Thymosin beta-4 trials used 0.1% eye drops, gels of 0.01% to 0.1% on skin wounds and IV doses, and none of them tested TB-500135714.

Go deeper

Sources

  1. 1Assessment of the Safety and Efficacy of RGN-259 Ophthalmic Solutions for Dry Eye Syndrome: ARISE-2 (NCT02974907) ClinicalTrials.gov, 5 Jan 2022. clinicaltrials.gov
  2. 2Safety and Efficacy of Thymosin Beta 4 Ophthalmic Solution in Patients With Dry Eye (NCT01387347) ClinicalTrials.gov, 10 Jul 2015. clinicaltrials.gov
  3. 3Study of Thymosin Beta 4 in Patients With Venous Stasis Ulcers (NCT00832091) ClinicalTrials.gov, 30 Mar 2010. clinicaltrials.gov
  4. 4The effect of thymosin treatment of venous ulcers Annals of the New York Academy of Sciences, Apr 2010. pubmed.ncbi.nlm.nih.gov
  5. 5Study of Thymosin Beta 4 in Patients With Pressure Ulcers (NCT00382174) ClinicalTrials.gov, 1 Feb 2010. clinicaltrials.gov
  6. 6Safety and Efficacy Study of Thymosin Beta 4 in Patients With Acute Myocardial Infarction (NCT05485818) ClinicalTrials.gov, 3 Aug 2022. clinicaltrials.gov
  7. 7A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers Annals of the New York Academy of Sciences, Apr 2010. pubmed.ncbi.nlm.nih.gov
  8. 8A Phase 2 Study on Effect of Thymosin Beta 4 on Wound Healing in Patients With Epidermolysis Bullosa (NCT00311766) ClinicalTrials.gov, 12 May 2014. clinicaltrials.gov
  9. 9Assessment of the Safety and Efficacy Study of RGN-259 Ophthalmic Solutions for Neurotrophic Keratopathy: SEER-1 (NCT02600429) ClinicalTrials.gov, 30 Aug 2023. clinicaltrials.gov
  10. 100.1% 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 International Journal of Molecular Sciences, 29 Dec 2022. pubmed.ncbi.nlm.nih.gov
  11. 11Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial Cornea, May 2015. pubmed.ncbi.nlm.nih.gov
  12. 12FDA Briefing Document, Pharmacy Compounding Advisory Committee meeting of July 23-24, 2026: TB-500-related bulk drug substances U.S. Food and Drug Administration, 15 May 2026. fda.gov
  13. 13PubMed search: TB-500, TB500, TB 500 or Ac-LKKTETQ in titles and abstracts (33 results; none gave TB-500 to people) National Library of Medicine (PubMed), accessed 8 Oct 2026. pubmed.ncbi.nlm.nih.gov
  14. 14Assessment of the Safety and Efficacy of RGN-259 Ophthalmic Solutions for Dry Eye Syndrome: ARISE-3, NCT03937882 ClinicalTrials.gov, 28 Aug 2026. clinicaltrials.gov
  15. 15TB-500 5 mg Dosage: Vial Chart & Protocol PeptideDosages, 28 Sep 2026. peptidedosages.com
  16. 16Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study Joint Diseases and Related Surgery, 23 Jul 2026. pubmed.ncbi.nlm.nih.gov
  17. 17Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats by UHPLC-Q-Exactive orbitrap MS/MS and their screening by wound healing activities in-vitro Journal of Chromatography B, 1 Mar 2024. pubmed.ncbi.nlm.nih.gov
  18. 18TB-500: safety testing results and vendor ratings Finnrick, 25 Sep 2026. finnrick.com
  19. 19Thymosin 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. pubmed.ncbi.nlm.nih.gov
  20. 20RegeneRx Reports Topline Results of ARISE-3 Dry Eye Trial RegeneRx Biopharmaceuticals (PR Newswire), 18 Mar 2021. prnewswire.com
  21. 21RegeneRx JV Announces Results of ARISE-2 Dry Eye Trial RegeneRx Biopharmaceuticals, 31 Oct 2017. regenerx.com
  22. 22TB-500 (Thymosin Beta 4 17-23 Fragment) for Cardiovascular Biomarkers in Stable ASCVD (NCT07487363) ClinicalTrials.gov, 23 Mar 2026. clinicaltrials.gov
  23. 23The PEPTIDE-L Wave Rolls On! PCAC Adds Two More Bulk Drug Substances for the 503A List FDA Law Blog (Hyman, Phelps & McNamara), 28 Jul 2026. thefdalawblog.com

Not medical advice. Talk to a licensed clinician before using any drug. Report an error.