TB-500

Last Updated: August 2026

TB-500 is a synthetic fragment of Thymosin Beta-4 (Tβ4) — specifically the active region containing the actin-binding domain — researched for tissue repair, wound healing, anti-inflammatory effects, and cardiac tissue recovery. It is one of the most-researched tissue-repair peptides alongside BPC-157. Important regulatory update: TB-500 was removed from the FDA's Category 2 bulk drug substances list on April 22, 2026 because the nomination had been withdrawn by the nominators, and at its July 23–24, 2026 meeting the Pharmacy Compounding Advisory Committee voted 8–6–1 to recommend it for the 503A compounding bulks list — an advisory recommendation only, which the FDA has not finalized.

What is TB-500 and how does the Thymosin Beta-4-derived mechanism work?

TB-500 is a short synthetic fragment of thymosin β4 — specifically the seven-residue Ac-LKKTETQ actin-binding motif (residues 17–23 of the 43-amino-acid full Tβ4 protein), molecular weight about 889 Da1 source, proposed to act through actin sequestration and release mechanisms that modulate cell migration, angiogenesis, and tissue regeneration. Thymosin Beta-4 itself is a major intracellular protein involved in cytoskeletal regulation; the synthetic fragment retains many of the regenerative effects of full Tβ4 with simplified pharmacokinetics. Evidence level: Preclinical extensive (wound healing, cardiac repair, neural regeneration); limited human clinical research; PCAC recommended it 8–6–1 for the 503A bulks list (July 2026, advisory, not finalized).

What does the research show for TB-500?

Preclinical studies have demonstrated effects on wound healing, cardiac tissue recovery post-MI, corneal repair, neural regeneration, and broad tissue-repair mechanisms across multiple animal models. Full-length Thymosin Beta-4 (RGN-352) has been studied in Phase 2 trials for diabetic foot ulcers and other indications by RegeneRx; TB-500 specifically (the fragment) is more commonly used in research and community contexts. No human trial has studied the TB-500 fragment itself. A 2026 scoping review of thymosin β4 and TB-500 across tissue healing screened 1,772 records, included 80 studies, and found direct TB-500 evidence limited to a single included study — with human evidence concentrated in ocular/corneal and wound/skin settings, not the tendon, ligament, muscle, bone, or cartilage indications TB-500 is marketed for.1 source At its July 2026 meeting the Pharmacy Compounding Advisory Committee voted 8–6–1 to recommend TB-500 for the 503A compounding bulks list — advisory only, not finalized. Evidence level: Preclinical extensive across multiple tissue contexts; full Tβ4 has Phase 2 human data; no human trial of the TB-500 fragment itself; PCAC recommended it 8–6–1 for the 503A bulks list (July 2026, advisory, not finalized).

How does TB-500 compare to BPC-157 and full Thymosin Beta-4?

TB-500 (the fragment) and full-length Thymosin Beta-4 are mechanistically related but pharmacokinetically different — the fragment is more commonly used in research-grade markets, full Thymosin Beta-4 has more direct clinical development history. BPC-157 and TB-500 are the two flagship tissue-repair peptides; they are often paired in community protocols though no formal head-to-head comparison data exists.

What are the documented side effects of TB-500?

Side effects in available preclinical safety data and community-reported research use are generally mild — injection-site reactions are the most common report. Theoretical concerns about angiogenesis effects (relevant for cancer biology) have been raised — similar to BPC-157 — given Thymosin Beta-4's role in vascular development. Clinical substantiation of these concerns is absent in available data. Long-term safety in humans at sustained research-use dosing is not characterized at Western RCT standards. Evidence level: Preclinical safety; human long-term unestablished; theoretical angiogenesis concerns unaddressed.

What is the regulatory status of TB-500?

TB-500 is not approved for any medical indication anywhere in the world as of August 2026. On April 22, 2026 the FDA removed TB-500 from its Category 2 bulk drug substances list because the nomination had been withdrawn by the nominators — the agency's own framing. Removal did not add TB-500 to the 503A bulks list or to Category 1, and does not by itself authorize compounding.1 source At its July 23–24, 2026 meeting the FDA's Pharmacy Compounding Advisory Committee voted 8–6–1 to recommend TB-500 for the 503A compounding bulks list — an advisory recommendation only, which FDA scientific staff opposed and the agency has not finalized; compounding stays unlawful under 503A pending formal rulemaking (not expected before 2027).1 source Current status in FDA peptide regulation 2025–2026 timeline.

Why does TB-500 vendor verification matter?

TB-500 is widely sold in research-grade markets with substantial quality variance, and the distinction between TB-500 (the ~889 Da Ac-LKKTETQ fragment) and full thymosin β4 (the ~4,963 Da, 43-amino-acid parent protein) requires mass-spectrometry verification — the ~4,000 Da mass gap is the cleanest identity check1 source — some vendors sell one mislabeled as the other. Independent HPLC purity testing is the standard quality signal. As with BPC-157, the acetate versus free base form should be clearly identified. Guidance in how-to-test-peptides hub.

How does Peptigrity verify TB-500 vendors?

Peptigrity collects independent third-party Certificates of Analysis for TB-500 from shops' official channels and verifies each for authenticity before publishing. Because shops choose which COAs to publish, results reflect the batches shops have made public rather than every production batch — a selection bias we state openly. A community-funded Testing Grant to purchase and test vials anonymously is in development. Tests in the database come from independent labs such as Janoshik Analytical, Freedom Diagnostics, and Chromate. Methodology in how we calculate trust scores.

Frequently Asked Questions

What does TB-500 do?

TB-500 is researched for tissue repair, wound healing, cardiac tissue recovery, and broad regenerative effects through actin-binding mechanisms related to cell migration and tissue regeneration. Preclinical evidence is extensive; the July 2026 PCAC review will evaluate the proposed wound healing indication.

Is TB-500 legal to purchase?

TB-500 is legal to purchase as a research chemical for laboratory use in most jurisdictions, but it is not approved for human consumption. The April 22, 2026 Category 2 removal reflects a withdrawn nomination, and the July 2026 PCAC vote was advisory only — neither authorizes compounding, and compounding stays unlawful under 503A pending formal rulemaking. Country breakdown in peptide legal status guide.

When will the FDA decide on TB-500?

The Pharmacy Compounding Advisory Committee will review TB-500 on July 23, 2026, evaluating its proposed use for wound healing. The PCAC will make a recommendation to the FDA on 503A bulks list inclusion. Track developments in FDA peptide regulation 2025–2026 timeline.

Is TB-500 the same as Thymosin Beta-4?

No. TB-500 is the short seven-residue Ac-LKKTETQ actin-binding fragment (~889 Da); thymosin β4 is the full 43-amino-acid parent protein (~4,963 Da). They are different molecules, and most published efficacy research used the full-length protein, not the fragment.1 source Both are mechanistically related; the fragment is more common in research-grade markets, full Tβ4 (RGN-352) has more direct pharmaceutical clinical development history.

Does TB-500 cause cancer?

The theoretical angiogenesis-related concern (similar to BPC-157) has been raised in mechanism discussions but has not been clinically substantiated. Long-term human surveillance has not been conducted at scale. Anyone with active cancer or cancer history should consult a licensed physician before considering TB-500.

How can I verify a TB-500 vendor is selling real product?

Independent third-party HPLC certificate of analysis from a lab the vendor does not own or pay, with mass spectrometry identity confirmation distinguishing TB-500 (the ~889 Da Ac-LKKTETQ fragment) from full Thymosin Beta-4 (~4,963 Da) and from related Thymosin Beta-4 fragments. Verify whether acetate or free base form. COA interpretation in red flags in peptide certificates of analysis.

Does Peptigrity recommend a TB-500 dose?

No. TB-500 is not approved for human consumption and Peptigrity is an independent review platform, not a medical authority. Research-use dosing in community protocols varies widely. Anyone considering use should consult a licensed physician.

Does TB-500 show up on a drug test?

Yes. Yes. TB-500 and thymosin β4 are prohibited by WADA at all times under S2.3 (Growth Factors and Growth Factor Modulators) — not the S2.1 peptide-hormone subsection — so both are banned in and out of competition as of August 2026.1 source Detection methods for Thymosin Beta-4 fragments have been developed and improved. For drug-testing context, see do peptides show up on drug tests.

This section is for educational and informational purposes only and does not constitute medical advice. TB-500 is not approved by the FDA or any major Western regulator for human use, though it was removed from Category 2 of the FDA 503A bulk substances list in April 2026 and is scheduled for PCAC review on July 23, 2026 for the proposed use in wound healing. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.