TB-500
Evidence: ERepair / Tissue Healing
Key facts
- Research areaRepair / Tissue Healing
- Research statusunclear
- Study records185 human
- Study-at-a-Glance1published summaries
- Last updated2026-08-09
Evidence Snapshot
What this grade covers
E: No direct human exposure, efficacy, pharmacokinetic, or safety evidence was identified for the exact TB-500/LKKTETQ fragment. Human evidence involving full-length thymosin beta-4, recombinant or synthetic Tβ4, and RGN-259 is molecule-, formulation-, route-, and indication-specific contextual evidence only. Regulatory records establish identity, absence-of-data, compounding-safety, advisory-process, and anti-doping context but do not establish clinical benefit.
Regulatory Context
No FDA-approved TB-500 fragment drug product was identified. FDA reports no identified human exposure data for the exact LKKTETQ fragment and has published compounding-safety concerns involving aggregation, peptide impurities, immunogenicity, and product characterization. FDA staff proposed against adding TB-500 free base and acetate to the 503A Bulks List during the July 2026 review; the advisory process did not itself create FDA approval, an approved indication, or an approved dosing regimen. TB-500 is prohibited under applicable WADA rules.
In Plain English
A quick, research-focused overview. It does not replace, and cannot outrank, the detailed evidence below.
What is it?
As used on this page, TB-500 refers specifically to the short LKKTETQ fragment derived from thymosin beta-4 (Ac-LKKTETQ) -- not the full-length 43-amino-acid thymosin beta-4 protein, and not RGN-259, a separate full-length-thymosin-beta-4-based ophthalmic formulation. No FDA-approved TB-500 product exists, and FDA's own 2026 evaluation found inconsistent identity and naming among TB-500 products in the market, a market-level concern separate from this page's own fragment-specific definition.
Why are researchers interested in it?
The TB-500/LKKTETQ fragment has been studied analytically -- methods to detect and quantify it and its metabolites, including for anti-doping purposes -- and in limited in-vitro and rat experiments screening for wound-healing activity. Separately, full-length thymosin beta-4 and the related ophthalmic formulation RGN-259 have been studied in human trials for wound healing, corneal conditions, and cardiac and dermal repair, but those studies concern different molecules, formulations, and routes, and do not establish TB-500 fragment efficacy, safety, or dosing.
What is it being studied for?
- Fragment-specific analytical and preclinical research (rat/in-vitro)Animal / Cell / Preclinical Data
- Full-length thymosin beta-4 and RGN-259 human trials (different molecule, contextual only)Human Studies & Clinical Data
- Tendon, ligament, muscle repair, and sports-injury claims (no approved indication)Regulatory Documents & Official Trial Registries
- Compounding bulk-substance regulatory statusRegulatory Documents & Official Trial Registries
What does the evidence look like?
Evidence for the TB-500 fragment itself is extremely limited. FDA reports it has not identified any human exposure data for drug products containing the exact TB-500/LKKTETQ fragment -- there is no human pharmacokinetic, efficacy, or safety evidence for TB-500 itself. The available fragment-specific research is preclinical and analytical: rat and in-vitro pharmacokinetic/metabolite work, and an in-vitro fibroblast scratch assay in which, per FDA's own 2026 evaluation, TB-500 did not significantly improve wound closure at the tested concentration. Human studies of full-length thymosin beta-4 and RGN-259 are real, controlled clinical evidence, but for different molecules, formulations, routes, and indications, and cannot be used to support TB-500 fragment claims.
Biggest things to know
No FDA-approved TB-500 product exists, and FDA reports no identified human exposure data for the exact fragment -- there is no established human safety profile for TB-500 itself, only for the biologically related but distinct full-length thymosin beta-4 and RGN-259. FDA's 2026 evaluation also found inconsistent identity and naming among TB-500 products in the market, inadequate physicochemical/quality characterization, no adequate nonclinical toxicology, and aggregation, impurity, immunogenicity, and sterility concerns for compounded material. TB-500 and thymosin beta-4 derivatives are included on the 2026 WADA Prohibited List. A July 2026 FDA advisory committee voted 8-6, with one abstention, to recommend TB-500 as a possible candidate for the compounding bulk-substances list -- an advisory, nonbinding vote that did not create FDA approval, an approved indication, or an approved dosing regimen, and that stands alongside FDA staff's own more cautionary technical evaluation.
What don't we know yet?
Whether TB-500 produces any human tissue-repair, wound-healing, tendon-repair, muscle-repair, or recovery benefit is not established -- no human evidence for the exact fragment exists, only preclinical/analytical work and contextual evidence from different, related molecules. Long-term human safety, and pregnancy, reproductive, developmental, and pediatric safety, have not been established for the exact fragment. Whether the theoretical cancer-related caution associated with thymosin-beta-4-related angiogenesis and cell-migration biology applies to human TB-500 use is not established either way by the evidence reviewed. Because FDA's own evaluation found inconsistent identity and naming across TB-500 products in the market, it is not established that any given vendor product actually matches the specific LKKTETQ fragment definition used on this page.
Research status
Reviewed August 25, 2026
Research Takeaway
TB-500 is represented on this page as the short LKKTETQ thymosin-beta-4-derived fragment, not full-length thymosin beta-4.
See all 10 evidence claims →Quick Summary
TB-500 is marketed as the short thymosin-beta-4 fragment LKKTETQ and is not the same molecule as full-length 43-amino-acid thymosin beta-4. FDA reports no identified human exposure data for drug products containing the exact fragment. Human studies of full-length thymosin beta-4 and RGN-259 are related biological context only and do not establish TB-500 efficacy, safety, pharmacokinetics, or dosing.
Mechanism & Research Overview
The LKKTETQ sequence is discussed in relation to actin binding, cell migration, angiogenesis, and tissue-remodeling biology associated with thymosin-beta-4 research. However, the marketed TB-500 fragment is molecularly distinct from full-length thymosin beta-4, and findings from full-length, recombinant, synthetic, or ophthalmic thymosin-beta-4 products cannot be transferred directly to TB-500.
Evidence Grade Breakdown
A single letter grade can't capture how evidence quality differs across approved use, off-label use, and unsupported claims. The categories below break that down -- none of them grade this compound "overall."
Overall Research Grade
TB-500 has no identified direct human exposure, efficacy, pharmacokinetic, or safety evidence for the exact LKKTETQ fragment. The available human studies involve molecule-distinct full-length thymosin beta-4 or RGN-259 products and are retained only as related biological context. FDA and WADA records provide identity, absence-of-data, compounding-safety, advisory-process, and anti-doping information but do not establish clinical effectiveness.
CCompound Identity
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Compound Identity
FDA materials identify the reviewed TB-500 substance as the LKKTETQ fragment and distinguish it from full-length thymosin beta-4. Commercial product identity, acetylation state, purity, and formulation may still vary.
EDirect Human TB-500 Evidence
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Direct Human TB-500 Evidence
No direct human exposure, efficacy, pharmacokinetic, or safety evidence was identified for the exact TB-500 fragment.
DRelated Full-Length Tβ4 Evidence
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Related Full-Length Tβ4 Evidence
Human studies exist for full-length, recombinant, or synthetic thymosin beta-4 and RGN-259, but these are molecule-, route-, formulation-, and indication-specific and cannot be counted as direct TB-500 evidence.
ESafety Evidence
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Safety Evidence
Fragment-specific human safety, long-term safety, reproductive safety, pediatric safety, pharmacokinetics, and immunogenicity remain inadequately characterized. FDA identifies additional aggregation, impurity, and product-characterization concerns.
CRegulatory and Anti-Doping Context
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Regulatory and Anti-Doping Context
FDA records document the fragment identity, absence of identified human exposure data, compounding-safety concerns, and the nonbinding 503A advisory process. WADA materials prohibit TB-500 for covered athletes. These records do not establish clinical approval or efficacy.
ERepair, Recovery, and Performance Claims
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Repair, Recovery, and Performance Claims
Controlled human evidence does not establish that the exact fragment improves tendon, ligament, muscle, wound-healing, recovery, bodybuilding, anti-aging, or athletic-performance outcomes.
Evidence reviewed
Covers the final TB-500 source graph: regulatory records directly addressing the LKKTETQ fragment, compounding-safety and 503A review, WADA status, human studies of molecule-distinct full-length thymosin beta-4 or RGN-259, related trial registries, one animal study, 2 direct analytical-identity studies for the exact fragment, and contextual full-length-Tβ4 reviews. No source provides direct human efficacy, pharmacokinetic, or safety evidence for the exact TB-500 fragment.
- Randomized human trials
- 3
- Observational human studies
- 2
- Regulatory documents
- 4
- Preclinical studies
- 2
- Primary sources reviewed
- 15 of 18
Study counts describe the reviewed evidence base. They do not independently determine evidence quality.
How MitoCore grades evidence
Grade definitions
- A
- Strong and directly applicable evidence, generally including regulatory support or multiple high-quality replicated human trials for the exact claim and population.
- A-
- Strong human evidence with limited uncertainty, narrower applicability, or incomplete replication.
- B+
- Moderately strong evidence with meaningful human support but important scope, duration, safety, or generalizability limitations.
- B
- Credible evidence with notable uncertainty, limited replication, or mixed results.
- C
- Preliminary or inconsistent evidence, usually limited human data or strong indirect evidence.
- D
- Weak, indirect, population-limited, or largely unsupported evidence for the specific use being graded.
- F
- No credible supporting evidence, evidence contradicting the claim, or claims based primarily on speculation or marketing.
Confidence definitions
- High
- The evidence classification is unlikely to change substantially with ordinary additional research.
- Moderate
- The classification is reasonably supported but could change with additional high-quality evidence.
- Low
- The evidence base is sparse, indirect, inconsistent, or dependent on uncertain assumptions.
- Very Low
- The evidence base is extremely limited, speculative, or unsuitable for firm conclusions.
Scope
The grade evaluates the evidence supporting the specific category or claim. A grade does not evaluate product purity, supplier quality, personal suitability, treatment appropriateness, individual outcomes, legality, or medical safety for a specific person.
These grades and confidence levels describe the research evidence itself. They are not medical recommendations, and they do not evaluate any specific product, supplier, or individual's situation.
Evidence Claims
Individual scientific statements drawn from the sources cited below, each shown with the specific evidence boundary that statement does not establish.
Supported
TB-500 is represented on this page as the short LKKTETQ thymosin-beta-4-derived fragment, not full-length thymosin beta-4.
Sources: Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks
Supported
FDA reports that it has not identified human exposure data for drug products containing the exact thymosin-beta-4 LKKTETQ fragment.
Sources: Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks
Supported
Human studies of full-length, recombinant, or synthetic thymosin beta-4 do not establish the efficacy, safety, pharmacokinetics, or dosing of the shorter TB-500 fragment.
Sources: A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers; A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteers
Supported
RGN-259 ophthalmic studies are formulation-, route-, indication-, and molecule-specific contextual evidence and cannot be treated as direct evidence for TB-500.
Supported
FDA identifies potential aggregation, peptide-impurity, immunogenicity, and characterization concerns for compounded products containing the fragment.
Sources: Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks
Supported
FDA's PCAC evaluation did not create approval, an approved indication, or an approved dosing regimen for TB-500.
Sources: FDA Briefing Document — Pharmacy Compounding Advisory Committee Meeting, July 23–24, 2026; FDA Advisory Panel Vote on Unapproved Peptides
Supported
The 2026 WADA Prohibited List includes thymosin-beta-4 and derivatives such as TB-500.
Sources: The 2026 Prohibited List
Supported
Analytical and anti-doping studies can identify TB-500/Ac-LKKTETQ and its metabolites but do not establish therapeutic benefit.
Sources: 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; Simultaneous 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
Supported
Preclinical findings involving LKKTETQ or full-length Tβ4 must remain separated by exact molecular identity and model.
Sources: FDA Evaluation of TB-500-Related Bulk Drug Substances; Thymosin beta4 accelerates wound healing
Supported
No direct human efficacy claim for tissue healing, recovery, performance, or injury treatment is supported for the exact TB-500 fragment.
Sources: Thymosin Beta-4 and Venous Ulcers; RGN-259 Dry Eye Trial; Thymosin Beta-4 in Pressure Ulcers; Recombinant Thymosin Beta-4 in Acute Myocardial Infarction
Safety & Evidence Limitations
Considerations reported in the sources cited on this page — not a complete list of every possible risk, and not medical advice.
Higher-Priority Safety Consideration
FDA reports no identified human exposure data for drug products containing the TB-500/LKKTETQ fragment. Human exposure, pharmacokinetics, efficacy, and safety therefore remain unestablished for the exact fragment.Higher-Priority Safety Consideration
Human trials involving full-length, recombinant, or synthetic thymosin beta-4 and RGN-259 study molecule-distinct products. Their efficacy and safety findings cannot be transferred directly to the shorter TB-500 fragment.Higher-Priority Safety Consideration
FDA identifies aggregation, peptide impurities, immunogenicity, acetylation state, molecular identity, and product characterization as material concerns for compounded TB-500 fragment products.Higher-Priority Safety Consideration
Unapproved injectable products may carry sterility, contamination, concentration, formulation, storage, and labeling risks that are not resolved by biological research involving thymosin beta-4.Higher-Priority Safety Consideration
Long-term human safety has not been established for the exact TB-500 fragment. Short-duration or molecule-distinct thymosin-beta-4 studies cannot resolve chronic fragment-specific risks.Higher-Priority Safety Consideration
Adequate pregnancy, reproductive, developmental, and pediatric safety data were not identified for the exact TB-500 fragment.Higher-Priority Safety Consideration
TB-500 is prohibited for athletes subject to applicable World Anti-Doping Code rules.Safety Consideration
Thymosin-beta-4 biology is associated with angiogenesis and cell migration. These mechanisms create context-dependent theoretical cancer-related concerns, but the reviewed evidence does not establish that the TB-500 fragment causes or accelerates cancer in humans.Safety Consideration
The July 2026 Pharmacy Compounding Advisory Committee process was advisory and nonbinding. It did not create FDA approval, an approved indication, or an approved dosing regimen for TB-500.
Research Areas Being Studied
Research areas discussed on this page reflect the Repair / Tissue Healing category and the sources cited below.
Findings Reported in Studies
Educational summary only — reported in cited studies, not a claim of proven benefit.
Show findings from 5 human studies
- 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 (2023): 0.1% ophthalmic full-length thymosin beta-4 formulation.
- A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteers (2021): Single and multiple intravenous doses of recombinant full-length thymosin beta-4.
- A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers (2010): Single and multiple intravenous doses of full-length thymosin beta-4.
- RGN-259 Dry Eye Trial ():
- Thymosin Beta-4 and Venous Ulcers ():
Study Tables by Evidence Type
18 study records · 1 with a Study-at-a-Glance summary
- Human Studies & Clinical Data 5
- Animal / Cell / Preclinical Data 3
- Regulatory Documents & Official Trial Registries 7
Human Studies & Clinical Data(5)
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
2023PMID 36613994
- Population / Model
- Patients with neurotrophic keratopathy
- Dose / Duration / Finding
0.1% ophthalmic full-length thymosin beta-4 formulation.
Safety note
Related-identity and indication-specific evidence only.
A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteers
2021PMID 34346165 · DOI 10.1111/jcmm.16693
- Population / Model
- Healthy Chinese volunteers
- Dose / Duration / Finding
Single and multiple intravenous doses of recombinant full-length thymosin beta-4.
Safety note
Related-identity evidence only.
A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers
2010PMID 20536472 · DOI 10.1111/j.1749-6632.2010.05474.x
- Population / Model
- Healthy volunteers
- Dose / Duration / Finding
Single and multiple intravenous doses of full-length thymosin beta-4.
Safety note
Related-identity evidence only; do not transfer directly to TB-500 fragment products.
RGN-259 Dry Eye Trial
PMID 25826322
- Population / Model
- Dose / Duration / Finding
An ophthalmic dry-eye trial of RGN-259, a full-length-thymosin-beta-4-based investigational formulation. Route-, formulation-, indication-, and molecule-specific -- does not validate injectable TB-500 for tendon, ligament, muscle, or systemic repair.
Thymosin Beta-4 and Venous Ulcers
PMID 17495250
- Population / Model
- Dose / Duration / Finding
A human study of full-length 43-amino-acid thymosin beta-4 in venous ulcers. This concerns a different molecule and formulation than the marketed TB-500 fragment and does not validate TB-500 efficacy, safety, or dosing.
Animal / Cell / Preclinical Data(3)
Simultaneous 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
2024PMID 38382158
- Population / Model
- Dose / Duration / Finding
Developed and applied a UHPLC-Q-Exactive orbitrap MS/MS method to simultaneously quantify TB-500 and its metabolites in in-vitro experiments and rats, with in-vitro wound-healing activity screening.
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
2012PMID 22962027
- Population / Model
- Dose / Duration / Finding
Synthesized and characterized the N-terminal acetylated LKKTETQ (Ac-LKKTETQ) fragment identified in TB-500, establishing direct analytical/molecular identity for anti-doping detection purposes.
Thymosin beta4 accelerates wound healing
1999PMID 10469335
- Population / Model
- Rat wound model
- Dose / Duration / Finding
Topical/intraperitoneal Tβ4 — Increased re-epithelialization and wound contraction in rat model.
Safety note
Preclinical only; animal/cell findings do not establish human safety or efficacy.
Regulatory Documents & Official Trial Registries(7)
Thymosin Beta-4 in Pressure Ulcers
NCT00382174
Study-at-a-Glance available
- Population / Model
- Dose / Duration / Finding
A registered trial of full-length thymosin beta-4 in pressure ulcers. Molecule-specific -- not TB-500 fragment evidence.
Key takeaway
In this trial of a topical thymosin beta 4 treatment for pressure ulcers in 72 adults, few ulcers healed by day 84: 3 of 18 on placebo and 8 of 54 on thymosin beta 4. Healing was not higher with the treatment.
Study at a Glance
Study at a Glance
Plain-language summary of: Thymosin Beta-4 in Pressure Ulcers
Did a thymosin beta 4 treatment applied to pressure ulcers help them heal?
Evidence status
What was being studied?
Whether thymosin beta 4 (Tβ4) applied directly to a pressure ulcer (a deep skin sore from prolonged pressure) was safe and helped the sore heal, at three strengths compared with a placebo. MitoCore files this study under its TB-500 / thymosin beta-4 subject. The trial itself tested a topical thymosin beta 4 preparation and never uses the name TB-500, so it does not show that any product sold under that name behaves the same way.
Who participated?
72 adults aged 18 to 85, all in the United States (56 men and 16 women; 17 were 65 or older). Each had at least one pressure ulcer with full-thickness skin loss and no exposed joint or bone, 5 to 70 square centimetres in area, that had been stable for at least a month, and a long-term blood sugar marker (HbA1c) of 8.5% or lower. 18 were assigned to placebo and 54 to thymosin beta 4 (three strengths).
How was the study done?
A Phase 2, randomized, double-blind, placebo-controlled dose-response trial. Participants applied a topical thymosin beta 4 preparation at 0.01%, 0.02% or 0.1% (by weight), or a matching 0% placebo preparation, once a day for up to 84 days, with adverse events recorded until day 99. The main measure was safety and tolerability; healing at day 84 was the secondary effectiveness measure. The registry reports the three thymosin beta 4 strengths combined as one group. This summary rests only on the ClinicalTrials.gov record and its posted results; no peer-reviewed report of the trial was found.
Key results
At day 84, 3 of 18 people on placebo (16.7%) and 8 of 54 on the three thymosin beta 4 strengths combined (14.8%) had healed ulcers, so healing was not higher with thymosin beta 4. The registry gives no results for the individual strengths and reports no statistical test. In the safety results, adverse events of some kind were counted for 18 participants on placebo and 53 on thymosin beta 4. Serious adverse events were counted for 5 on placebo and 13 on thymosin beta 4, and 4 of 54 people on thymosin beta 4 and 1 of 18 on placebo stopped because of an adverse event.
| Measure | Group | Timepoint | Reported value |
|---|---|---|---|
| Pressure ulcer healed at the end of treatment | Placebo (n=18) | Day 84 | 3 people (16.7%)Per-protocol, intention-to-treat and last-observation-carried-forward analyses are named in the registry. |
| Pressure ulcer healed at the end of treatment | Thymosin beta 4, three strengths combined (n=54) | Day 84 | 8 people (14.8%)Results for each strength are not reported. |
| Participants with a serious adverse event | Placebo / thymosin beta 4 combined | Up to day 99 | 5 / 13Group totals as posted; the registry gives the number of people at risk only for individual events. |
| Urinary tract infection (adverse event) | Placebo / thymosin beta 4 combined | Up to day 99 | 4 of 18 / 9 of 53 |
| Fever (pyrexia, adverse event) | Placebo / thymosin beta 4 combined | Up to day 99 | 1 of 18 / 8 of 53 |
| Stopped the study because of an adverse event | Placebo / thymosin beta 4 combined | Up to day 84 | 1 of 18 / 4 of 54 |
What does this mean?
Safety findings
Adverse events were counted for 18 people on placebo and 53 on thymosin beta 4 (safety population of 18 and 53); the registry data do not report a death count. Serious adverse events were counted for 5 people on placebo and 13 on thymosin beta 4; the most frequent were sepsis (2 of 18 vs 2 of 53), fever (0 vs 3 of 53), osteomyelitis (2 vs 1) and pneumonia (0 vs 2). Common non-serious events included urinary tract infection (4 of 18 vs 9 of 53), fever (1 vs 8), sepsis (2 vs 5) and wound complications (1 vs 4). Four of 54 people on thymosin beta 4 and 1 of 18 on placebo stopped because of an adverse event. The registry does not say which events were caused by the treatment.
Important limitations
- Small Phase 2 trial: 72 people, with 18 on placebo and 54 spread over three strengths.
- The registry reports the three thymosin beta 4 strengths as one combined group, so the dose-response question cannot be answered from the posted results.
- No statistical test or confidence interval is posted for healing, and healing was low in both groups.
- 21 of 72 people did not complete the study (4 of 18 on placebo and 17 of 54 on thymosin beta 4).
- The posted safety counts give group totals without the number of people at risk, and the groups were very different in size.
- No peer-reviewed report of this trial was found (PubMed search, accessed 2026-10-08), so the results rest on the registry alone; the trial was run by the sponsor and its results were posted in 2010.
Regulatory context
- Investigational use studied here
- Topical thymosin beta 4 was studied as an investigational treatment for pressure ulcers.
A search of Drugs@FDA for thymosin beta 4 (accessed 2026-10-08) found no application or approved product. The trial record does not use the name TB-500.
Sources
- Trial record
- ClinicalTrials.gov NCT00382174 — ClinicalTrials.gov
- Sources reviewed
- Trial registry record with posted results.
Other sources for this study (1)
- FDA Drugs@FDA search for thymosin beta 4 (accessed 2026-10-08) — Regulator (FDA / EMA) · No FDA application or approved product was found.Content reviewed for this summary
This summary is a plain-language reading aid written by MitoCore. It does not replace the original study, which remains the authoritative source. Research information only, not medical advice.
Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks
2026- Population / Model
- FDA safety and compounding review
- Dose / Duration / Finding
Exact-fragment identity and current human-data/safety statement.
Safety note
Applies to the TB-500 fragment, not full-length thymosin beta-4.
FDA Advisory Panel Vote on Unapproved Peptides
2026- Population / Model
- Dose / Duration / Finding
On July 23, 2026, the FDA Pharmacy Compounding Advisory Committee voted 8-6 with one abstention to recommend possible 503A-list inclusion for TB-500, KPV, and BPC-157. The vote was advisory and nonbinding and did not create FDA approval or an approved indication for any of the substances.
Show full finding
FDA Briefing Document — Pharmacy Compounding Advisory Committee Meeting, July 23–24, 2026
2026- Population / Model
- FDA advisory-committee review
- Dose / Duration / Finding
Staff proposal pending advisory process.
Safety note
The meeting remained upcoming on the research-review date.
FDA Evaluation of TB-500-Related Bulk Drug Substances
2026- Population / Model
- Dose / Duration / Finding
FDA's May 2026 evaluation of TB-500 free base and acetate for the 503A Bulks List found inconsistent identity and naming, inadequate physicochemical/quality characterization, no identified human administration data, no identified in-vivo pharmacologic wound-healing study, an in-vitro fibroblast scratch assay in which TB-500 did not significantly improve wound closure at the tested concentration, no adequate nonclinical toxicology, and immunogenicity/aggregation/impurity/sterility/endotoxin concerns.
Show full finding
The 2026 Prohibited List
2026- Population / Model
- Anti-doping regulatory list
- Dose / Duration / Finding
TB-500 is prohibited for athletes subject to the World Anti-Doping Code.
Safety note
Anti-doping status is separate from clinical safety or efficacy.
Recombinant Thymosin Beta-4 in Acute Myocardial Infarction
NCT07586865
- Population / Model
- Dose / Duration / Finding
A registered trial of recombinant full-length thymosin beta-4 in acute myocardial infarction. Molecule-specific -- not TB-500 fragment evidence.
Review Articles / Secondary Sources(3)
The regenerative peptide thymosin β4 accelerates the rate of dermal healing in preclinical animal models and in patients
2012PMID 23050815
- Population / Model
- Review
- Dose / Duration / Finding
Wound repair mechanisms — Discusses migration, stem-cell mobilization, and anti-inflammatory mechanisms.
Safety note
Secondary source; useful for context but not a substitute for primary study review.
Thymosin beta-4 regenerative peptide review
2011PMID 22074294
- Population / Model
- Review
- Dose / Duration / Finding
Basic science and clinical applications — Reviews repair/regeneration roles in injured tissues.
Safety note
Secondary source; useful for context but not a substitute for primary study review.
Thymosin beta 4: A novel corneal wound healing and anti-inflammatory agent
2009PMID 19668473
- Population / Model
- Review
- Dose / Duration / Finding
Corneal injury/inflammation — Summarizes corneal wound-healing and anti-inflammatory effects.
Safety note
Secondary source; useful for context but not a substitute for primary study review.
Anecdotal Reported Patterns — Not Medical Advice
Anecdotal Reported Patterns — Not Medical Advice
Reported dosing patterns are included for educational context only. They are self-reported, unverified, not medical advice, and not instructions for human use. Community-submitted patterns are not yet available in this Phase 1 prototype; this section is a placeholder reserved for moderated, aggregated community data.
Lab Markers to Discuss With a Clinician
Educational topics only — not self-monitoring instructions.
FAQ
Disclaimer
Evidence involving full-length thymosin beta-4, recombinant thymosin beta-4, synthetic thymosin beta-4, RGN-259, or other molecule-distinct products is presented only as related biological context. It does not establish the efficacy, safety, pharmacokinetics, or dosing of the shorter marketed TB-500/LKKTETQ fragment. This page does not provide treatment, repair, recovery, injection, or dosing recommendations.
Educational use only. This content is provided for informational and research-summary purposes only. It is not medical advice, not a treatment recommendation, not a dosing guide, and not a substitute for care from a licensed medical professional. Nothing here is intended to diagnose, treat, cure, prevent, or mitigate disease. Reported dosing patterns, when shown elsewhere on the site, must be labeled either as Study / Trial Dosing or Anecdotal Reported Patterns — Not Medical Advice. Community reports are self-reported, unverified, and not scientific proof.
Community-reported experiences, once enabled, must be displayed only as moderated, anonymized, or aggregated data. They are anecdotal, self-reported, unverified, and should never be presented as proof of safety, efficacy, or expected results.
Content status: Published. Last updated 2026-08-09.
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