Prof. PeptideProf. Peptide
Guide

How is TB-500 dosed?

TB-500 has no approved product and zero completed human trials of the fragment itself. Every human trial that exists tested a different, related molecule — full-length thymosin beta-4 — and this page never blends the two. What follows: the one animal study that tested TB-500 directly, the six thymosin beta-4 trials that didn’t, and where community dosing diverges from both.

Topic: Reading what was actually studied under the name TB-500 versus thymosin beta-4

Audience: Anyone comparing a TB-500 dose figure against what has (and hasn’t) been studied

Reading time: 9–11 minutes

Zero completed human trials of the TB-500 fragment itself

FDA’s own July 2026 evaluation states it is “particularly concerned about the absence of human data on drug products containing” TB-500, “administered via any ROA [route of administration].” No approved product exists anywhere. Every human trial reported on this page tested a different, full-length molecule — thymosin beta-4 — not TB-500. Every figure below is a fact about a specific study — not a recommendation.

On this page
  1. 1.TB-500 vs. thymosin beta-4: two different molecules
  2. 2.The human trials — all of them thymosin beta-4, not TB-500
  3. 3.The animal evidence, reported as animal doses
  4. 4.Is there a community-reported dose?
  5. 5.Regulatory position: FDA's own TB-500 evaluation and the PCAC vote
  6. 6.Related pages
  7. 7.FAQ
  8. 8.References

TB-500 vs. thymosin beta-4: two different molecules

TB-500 (also called the TB4 Fragment 17-23) is a synthetic 7-amino-acid peptide, sequence Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH, reported to reproduce part of the actin-binding activity of a much larger protein. Thymosin beta-4 (Tβ4) is that larger protein — a naturally occurring 43-amino-acid peptide from the thymus gland — and it is Tβ4, not TB-500, that RegeneRx Biopharmaceuticals and other sponsors have taken into human clinical trials. The TB-500 profile covers the mechanism and broader research context; this page exists specifically to keep that distinction visible in every trial and study cited.

The evidence below is ordered the way the site’s own convention places it: real studies of TB-500 itself first (there is exactly one, in animals), then the thymosin beta-4 human trials — clearly labeled as a different molecule, not blended in as if they were evidence for TB-500 — then community-reported practice last, attributed and marked unverified.

The human trials — all of them thymosin beta-4, not TB-500

Six registered trials of full-length thymosin beta-4 were found and re-pulled directly from the ClinicalTrials.gov API. None of them is a trial of TB-500. A registry entry that appears to describe an active, recruiting TB-500 trial (NCT07487363) was checked directly and found to be a ClinicalTrials.gov example record — its own description states it “models common ClinicalTrials.gov data elements for an interventional study” and that “the specific dose levels are protocol-defined and are not provided in this public example.” It is not a real trial and is not cited as evidence anywhere on this page.

Epidermolysis Bullosa — Topical Thymosin Beta-4

NCT00311766

TERMINATED (per the registry: "Lack of patient availability and expiration of study drug" — not a safety or efficacy stop)

Design: Phase 2, randomized, double-blind, placebo-controlled trial testing topical thymosin beta-4 gel for wound healing in patients with epidermolysis bullosa.

Arms: 30 participants enrolled (actual, per the registry) before termination, randomized to placebo gel or thymosin beta-4 gel at 0.01%, 0.03%, or 0.1%, applied once daily for up to 56 days.

Pressure Ulcers — Topical Thymosin Beta-4

NCT00382174

COMPLETED, with results posted directly to the registry

Design: Phase 2, double-blind, placebo-controlled, dose-escalation trial testing topical thymosin beta-4 gel for pressure ulcers.

Arms: 72 participants (18 placebo, 54 across three active-dose arms: 0.01%, 0.02%, and 0.1% thymosin beta-4 w/w), applied topically once daily for up to 84 days.

Endpoint reported: Complete wound healing at day 84: 8 of 54 (14.8%) thymosin-beta-4-treated versus 3 of 18 (16.7%) placebo — no meaningful difference, consistent with the trial sponsor's own public reporting that no dose reached statistical significance for complete healing.

Adverse events reported: Any treatment-emergent adverse event was reported by essentially all participants in both arms (18 of 18 placebo; 53 of 54 thymosin-beta-4-treated) — a general AE tally over an 84-day observation period, not a specific safety signal.

Venous Stasis Ulcers — Topical Thymosin Beta-4

NCT00832091

COMPLETED

Design: Phase 2, double-blind, placebo-controlled, dose-response trial testing topical thymosin beta-4 gel for venous stasis ulcers.

Arms: 72 participants across three dose groups (18 active-drug and 6 placebo per group, per the registry's own group description), at three topical concentrations.

Acute Myocardial Infarction — Intravenous Recombinant Thymosin Beta-4 (three trials)

NCT05984134, NCT05485818, NCT07586865

First two COMPLETED (N=90 and N=62 actual); third NOT YET RECRUITING (N=189 estimated)

Design: Phase 2 trials of intravenous recombinant human thymosin beta-4 (branded NL005 in the registered protocols) as an adjunct after percutaneous coronary intervention for acute myocardial infarction — an entirely different program, sponsor, molecule form, and route than the topical wound-care trials above.

Arms: NCT05984134's dose arms: 0.5 microgram/kg ("middle dose") and 1.5 microgram/kg ("high dose"), continuous IV administration for 7 days, versus placebo.

The animal evidence, reported as animal doses

The dose below is what was given to an animal in a specific published study. Prof. Peptide does not convert it into a human-equivalent figure by allometric scaling or any other method.

Achilles Tendon Healing — TB-500 (the fragment, directly tested)

Biçer O, Adanir O, Güleryüz Y, et al. Jt Dis Relat Surg. 2026;37(3):822–837. PMID 42542926.

Species: Rat (Sprague-Dawley, male, 12 weeks old, ~330 g)

Dose: TB-500 ("synthetic thymosin beta-4") 60 microgram/kg/day; BPC-157 10 microgram/kg/day; and a combined TB-500 + BPC-157 arm, each versus untreated control

Route: Intraperitoneal

Duration: Daily for 4 weeks after standardized surgical Achilles tendon transection and repair

Finding: TB-500 alone produced a statistically significant increase in maximum load to failure versus control (p<0.05) and significantly lower Bonar and Movin histopathology scores (p=0.016 and p=0.017), indicating improved tendon architecture. Combined TB-500 + BPC-157 did not outperform either agent alone.

A larger animal literature exists for full-length thymosin beta-4 — dermal wound healing, traumatic brain injury, cardiac repair, and corneal models among them — but is not cataloged in full here, since this page’s focus is what has been studied under the TB-500 name specifically. The TB-500 profile covers that broader thymosin beta-4 research base.

Is there a community-reported dose?

Yes — a loading phase of 2.0–2.5 mg subcutaneously twice weekly (weeks 1–4), followed by a maintenance phase of 2.0 mg subcutaneously once weekly (weeks 5–8), is the figure consistently reported across vendor and blog dosing pages and already documented on the TB-500 profile. It is reported here, below the animal and trial evidence above, as observed practice attributed to where it circulates — not a studied dose.

It diverges from every study on this page. The thymosin-beta-4 human trials used a topical percentage gel (0.01–0.1% w/w) or a microgram-per-kilogram intravenous infusion — neither resembling a flat milligram subcutaneous injection. The one TB-500-specific animal study used 60 microgram per kilogram per day, intraperitoneal — a weight-based microgram dose, not a flat 2 mg figure. No source was found deriving the community protocol from either the human thymosin beta-4 trials or the TB-500 animal study.

Regulatory position: FDA’s own TB-500 evaluation and the PCAC vote

FDA’s own July 2026 staff evaluation weighs against 503A eligibility; the PCAC’s public vote recommends the opposite, non-bindingly.

Read directly from FDA’s own July 2026 Pharmacy Compounding Advisory Committee briefing document for TB-500 specifically: FDA states “there is a lack of clinical and nonclinical safety information on the use of TB-500 (free base) and TB-500 acetate,” and that it “is particularly concerned about the absence of human data on drug products containing these substances administered via any ROA.” The document’s conclusion states that “a balancing of the criteria weighs against TB-500 (free base) and TB-500 acetate being placed” on the 503A Bulks List, citing the same characterization and immunogenicity concerns found for BPC-157. TB-500 also appears in FDA’s 503A “bulk drug substances nominated but withdrawn” table, not the active Category 2 list — checked directly.

At the same July 23–24, 2026 PCAC public meeting where BPC-157 was voted on, the committee voted 8-6 (one abstention) in favor of adding TB-500 to the 503A Bulks List — against FDA staff’s own recommendation. This count is attributed to convergent press reporting of the public meeting, the same sourcing basis used on the BPC-157 guide, rather than re-extracted from a second raw FDA vote document. The vote is non-binding; FDA had not acted on it as of this page’s build.

Research-grade TB-500, of the kind sold by the vendors Prof. Peptide tracks elsewhere on this site, is neither an approved product nor a verified lawfully compounded one under the current regulatory position above. It is sold labeled for laboratory research use, not for human administration, and it is not dispensed against a prescription.

FAQ

Has TB-500 been tested in a human trial?
No completed human trial of the TB-500 fragment itself was found. FDA's own July 2026 evaluation states it "is particularly concerned about the absence of human data on drug products containing these substances administered via any ROA [route of administration]." A registry entry that appears to describe a real recruiting human trial of TB-500 (NCT07487363) was checked directly and found to be a ClinicalTrials.gov example/template record, not a genuine trial — its own text states "This example record models common ClinicalTrials.gov data elements for an interventional study." It is not cited as evidence anywhere on this page.
Is TB-500 the same thing as thymosin beta-4?
No, and the difference matters for reading any trial correctly. Thymosin beta-4 (Tβ4) is the full 43-amino-acid protein naturally produced by the thymus and studied in several human trials. TB-500 is a synthetic 7-amino-acid fragment (sequence Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH, sometimes called the TB4 Fragment 17-23) reported to reproduce part of Tβ4's actin-binding activity. Every human trial on this page tested full-length Tβ4, not TB-500 — labeled as such throughout.
What did the thymosin beta-4 trials actually test?
Six registered trials of full-length thymosin beta-4 exist, none of them TB-500. Three are RegeneRx's older topical wound-care program: epidermolysis bullosa (NCT00311766, terminated for non-efficacy reasons), pressure ulcers (NCT00382174, completed, no significant difference from placebo in wound healing at day 84), and venous stasis ulcers (NCT00832091, completed). Three are a newer, unrelated program testing intravenous recombinant thymosin beta-4 for acute myocardial infarction (NCT05984134, NCT05485818, NCT07586865) — a different sponsor, a different route, and a different molecule form than the topical gel trials.
What dose was used in the pressure ulcer trial?
NCT00382174 randomized 72 patients (18 placebo, 54 across three active-dose arms) to a topical gel of 0.00%, 0.01%, 0.02%, or 0.1% thymosin beta-4, applied once daily for up to 84 days. At day 84, 8 of 54 thymosin-beta-4-treated patients (14.8%) had complete wound healing, versus 3 of 18 on placebo (16.7%) — no meaningful difference. This is a topical percentage-concentration dose of full-length thymosin beta-4, not a milligram injection of TB-500.
Has TB-500 itself been studied in animals?
One study explicitly using the TB-500 fragment (not full thymosin beta-4) was found: Biçer et al. 2026, a rat Achilles-tendon-transection model, dosed at 60 microgram per kilogram per day, intraperitoneal, for 4 weeks. TB-500 showed a statistically significant biomechanical advantage (higher maximum load to failure) versus untreated controls at 4 weeks. This is an animal dose in a specific published study — not converted into a human figure here.
Is there a commonly reported TB-500 dosing protocol?
Yes — a loading phase of 2.0–2.5 mg subcutaneously twice weekly for 4 weeks, followed by a maintenance phase of 2.0 mg subcutaneously once weekly, is the figure consistently reported across vendor and blog sources and already documented on the TB-500 profile. It diverges sharply from every study on this page: the human thymosin-beta-4 trials used a topical percentage gel or a microgram-per-kg IV infusion, not a milligram subcutaneous injection, and the one TB-500-specific animal study used 60 micrograms per kilogram per day, not a flat 2 mg dose. No source was found deriving the community figure from either.
What is TB-500's current FDA compounding status?
Checked directly against FDA's own July 2026 Pharmacy Compounding Advisory Committee briefing document for TB-500 specifically: FDA's staff conclusion states the evaluation criteria "weigh against" placing TB-500 (free base or acetate) on the 503A Bulks List, citing the absence of any human exposure data and unresolved characterization concerns. TB-500 also appears in FDA's 503A "nominated but withdrawn" table, not the active Category 2 list. The Pharmacy Compounding Advisory Committee's public meeting on July 23–24, 2026 voted 8-6 (one abstention) in favor of listing it anyway — the same non-binding vote reported for BPC-157 at the same meeting, per convergent press coverage. FDA had not acted on it as of this page's build.

References

  1. Biçer O, Adanir O, Güleryüz Y, et al. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study. Jt Dis Relat Surg. 2026;37(3):822–837. PMID 42542926. https://pubmed.ncbi.nlm.nih.gov/42542926/
  2. ClinicalTrials.gov. A Phase 2 Study on Effect of Thymosin Beta 4 on Wound Healing in Patients With Epidermolysis Bullosa, NCT00311766. https://clinicaltrials.gov/study/NCT00311766
  3. ClinicalTrials.gov. Study of Thymosin Beta 4 in Patients With Pressure Ulcers, NCT00382174. https://clinicaltrials.gov/study/NCT00382174
  4. ClinicalTrials.gov. Study of Thymosin Beta 4 in Patients With Venous Stasis Ulcers, NCT00832091. https://clinicaltrials.gov/study/NCT00832091
  5. ClinicalTrials.gov. Efficacy and Safety Study of Thymosin Beta 4 in Patients With Acute Myocardial Infarction, NCT05984134. https://clinicaltrials.gov/study/NCT05984134
  6. U.S. Food and Drug Administration. FDA Briefing Document, Pharmacy Compounding Advisory Committee Meeting, July 23–24, 2026 — Evaluation of TB-500 Bulk Drug Substances. https://www.fda.gov/media/193349/download
  7. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks. https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks

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