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Reference information only. Therapept does not sell peptides and does not provide medical advice.Research-use notice

Therapept

Synthetic acetylated heptapeptide corresponding to the actin-binding region of thymosin beta-4 (residues 17–23)

TB-500 — evidence

What has been published, classified by the kind of document it is. This is not a protocol, not a score, and not a recommendation for use.

Evidence overview

6 records in this file

  • ANIMAL1
  • REVIEW2
  • REGULATORY3

Research areas. Anti-doping; Clinical evidence appraisal; Parent molecule (thymosin β-4); United States compounding.

Publication span. 1999–2026.

What we know

  • TB-500, as identified by FDA and PubChem, is the acetylated LKKTETQ heptapeptide, not full-length thymosin β-4 and not Ac-SDKP.
  • Wound-healing papers commonly cited in vendor material are usually about full-length Tβ4. They are not TB-500 studies.
  • FDA states it has not identified human exposure data. WADA lists “Thymosin-β4 and its derivatives e.g. TB-500”.

Editorial reading of the records below, labelled as Therapept analysis. How records are built

What remains uncertain

  • Published human data on the fragment itself, as opposed to the parent protein.
  • How often a certificate labelled “TB-500” describes LKKTETQ rather than another sequence.

Regulatory notes

No FDA-approved product

  • No approved drug product exists in Drugs@FDA.
  • Listed on FDA's table of bulk substances nominated for compounding and withdrawn by the nominator. FDA's published concerns include aggregation and immunogenicity risk, and FDA notes it has not identified human exposure data.
  • On 23 July 2026 PCAC discussed TB-500 (free base) and TB-500 acetate (use evaluated: wound healing). FDA briefing materials proposed that they NOT be included on the 503A Bulks List. Nominations had been withdrawn; FDA elected to proceed. Committee recommendations are non-binding; FDA has not published a listing decision as of this review.

Regulatory status describes how a substance is classified. It is not a safety assessment of any particular material.

Studies and documents

  1. REGULATORY2026FDA advisory-committee briefing

    FDA PCAC briefing — TB-500-related bulk drug substances (23 July 2026)

    U.S. Food and Drug AdministrationFDA PCAC briefing

    Objective
    To record FDA staff's published proposal on 503A Bulks List inclusion for TB-500.
    Endpoint investigated
    Proposed compounding-list classification

    PCAC discussed TB-500 (free base) and TB-500 acetate on 23 July 2026 (use evaluated: wound healing). The briefing-document introduction states that FDA is proposing that both NOT be included on the 503A Bulks List. Nominations had been withdrawn; FDA elected to proceed.

    Limitations. Staff proposal and committee advice are non-binding. FDA has not published a listing decision as of this review.

    FDA — PCAC briefing for TB-500-related bulk drug substancesReviewed 12 September 2026

  2. REGULATORY2026Regulatory listing

    FDA table of bulk drug substances nominated for compounding and subsequently withdrawn

    U.S. Food and Drug AdministrationFDA compounding communications

    Objective
    To record FDA's published compounding position on TB-500.
    Endpoint investigated
    Compounding classification

    Listed on FDA's withdrawn-nominations table. Published concerns include aggregation and immunogenicity risk; FDA notes it has not identified human exposure data. FDA and PubChem identify TB-500 as the LKKTETQ heptapeptide.

    Limitations. Withdrawn nomination; not a clinical trial review. Human exposure data are stated as not identified.

    FDA — Certain bulk drug substances for use in compounding may present significant safety risksReviewed 12 September 2026

  3. REVIEW2026Narrative review

    Injectable peptide therapy: a primer for orthopaedic and sports medicine physicians

    Mayfield CK, Bolia IK, Feingold CL, Lin EH, Liu JN, Hatch GFR, Gamradt SC, Weber AEThe American Journal of Sports Medicine

    Objective
    To separate published Tβ4/TB-500 claims from orthopaedic evidence.
    Endpoint investigated
    Human orthopaedic evidence for Tβ4 and TB-500

    The review states that Tβ4 and its derivative TB-500 promoted angiogenesis and tissue repair in preclinical models, that human orthopaedic data are lacking, and that both remain prohibited in sport.

    Limitations. Narrative. Treats Tβ4 and TB-500 in one breath — the chemical distinction still has to be kept on the identity record.

    DOI 10.1177/03635465251357593Mayfield et al., Am J Sports Med (2026)Reviewed 12 September 2026

  4. REVIEW2026Scoping review

    Peptide supplements and their therapeutic applications in sports medicine

    Tewari K, Liu TP, Im C, Hamad C, Petrigliano F, Cheung EC, Kremen TJThe American Journal of Sports Medicine

    Objective
    To scope musculoskeletal literature that uses TB-500 / thymosin β-4 search terms.
    Endpoint investigated
    Published musculoskeletal evidence

    Same scoping review as the BPC-157 row. Search terms combined TB-500 with thymosin β-4. Human clinical studies were described as limited.

    Limitations. Search conflates the fragment and the parent molecule. Identity caveat on the TB-500 record still applies.

    DOI 10.1177/03635465261464420Tewari et al., Am J Sports Med (2026)Reviewed 12 September 2026

  5. REGULATORY2026Anti-doping listing

    WADA Prohibited List — S2.3 Thymosin-β4 and its derivatives e.g. TB-500

    World Anti-Doping AgencyWADA Prohibited List

    Objective
    To record the 2026 Prohibited List entry.
    Endpoint investigated
    Sporting prohibition status

    Named at S2.3 — “Thymosin-β4 and its derivatives e.g. TB-500”. Prohibited at all times; non-Specified.

    Limitations. Anti-doping classification. Groups the fragment with the parent molecule by name.

    WADA 2026 Prohibited ListReviewed 12 September 2026

  6. ANIMAL1999In vivo (animal wound models) — parent molecule

    Thymosin β4 accelerates wound healing

    Malinda KM, Sidhu GS, Mani H, et al.Journal of Investigative Dermatology

    Population
    Animal full-thickness wound models
    Objective
    To test whether full-length thymosin β4 affected wound closure in animals.
    Endpoint investigated
    Wound closure with full-length Tβ4, not TB-500

    Full-length thymosin β4 was reported to accelerate wound healing in animal models. The paper is listed here because the commercial name TB-500 is routinely treated as interchangeable with Tβ4 — which it is not.

    Limitations. This is evidence about thymosin β4 (43 residues), not about the acetylated LKKTETQ heptapeptide sold as TB-500. Do not read it as a TB-500 study.

    DOI 10.1046/j.1523-1747.1999.00696.xMalinda et al., J Invest Dermatol (1999) — Full-length thymosin β4, not the TB-500 fragment.Reviewed 12 September 2026

Last reviewed 12 September 2026 · Compiled by Therapept Editorial · How these records are built