Skip to content

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

Therapept

43-residue N-terminally acetylated peptide

Thymosin beta-4

The full-length 43-residue peptide, INN timbetasin. It is a different substance from TB-500, the seven-residue LKKTETQ fragment sold under that name, and from Ac-SDKP, its first four residues. No FDA-approved drug product exists.

UnapprovedAlso listed as: Timbetasin, Thymosin β4, Tβ4

Why people are interested in Thymosin beta-4

The full-length 43-residue peptide, INN timbetasin. It is a different substance from TB-500, the seven-residue LKKTETQ fragment sold under that name, and from Ac-SDKP, its first four residues. No FDA-approved drug product exists.

  • Thymosins— a research-category classification, not a claimed use
  • Preclinical research compounds— a research-category classification, not a claimed use

Where the interest comes from differs by compound: published research, an approved use, clinical discussion, community discussion and vendor claims are different things. This page keeps them apart — the sections below say which kind of source supports each statement.

Quick facts

Molecular weight
4963 g/mol
Sequence length
46 chars
CAS number
77591-33-4
PubChem CID
16132341

0 evidence records indexed · 0 clinical trials · last reviewed 15 September 2026

Research at a glance

No evidence records in this file yet.

Open the full evidence file

What has actually been studied

    What is still unknown

    What we know

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

      What remains uncertain

        Preparation and handling

        Lyophilized peptides ship as powders; whatever happens next involves diluents, concentrations and storage conditions that are compound- and product-specific. Therapept’s preparation guides explain the vocabulary and the arithmetic; the product’s own documentation states its requirements.

        What “lyophilized” meansReconstitution basicsStorage, by source kindConcentration calculator

        United States regulatory status

        No FDA-approved product

        • No approved drug product exists in Drugs@FDA.
        • FDA's compounding tables list the fragment “Thymosin beta-4, fragment (LKKTETQ), also known as TB-500”, not the full-length peptide.
        • WADA's entry names thymosin-β4 and its derivatives together, so the parent peptide and the fragment fall under the same listing.

        Anti-doping status

        Named at S2.3 — “Thymosin-β4 and its derivatives e.g. TB-500”, among growth factors and growth factor modulators. Prohibited at all times.

        Regulatory status describes how a substance is classified. It is not a safety assessment, and it says nothing about the quality of any particular material.

        Technical identity

        Compound class
        43-residue N-terminally acetylated peptide; the parent molecule of the TB-500 fragment
        Sequence
        Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES
        Molecular formula
        C212H350N56O78S
        Molecular weight
        4963 g/mol
        CAS number
        77591-33-4
        PubChem CID
        16132341
        Research categories
        Thymosins, Preclinical research compounds