Last updated October 21, 2026. Approval line checked October 21, 2026. Compounding sources checked October 10, 2026.
FDA status
Not approved
Not approved. This record is not an FDA-approved drug product. Approval, where it exists, is specific to a drug product, indication, and route.
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Evidence tier
Animal Only. The tier is the highest indexed study type. It is not a safety rating and it is not an FDA approval. Confidence score 3/5. 107 PubMed citations indexed.
The TB4-Frag variant 'TB-500' refers to the actin-binding motif LKKTETQ (residues 17-23 of full-length Thymosin Beta-4) which sequesters G-actin monomers, modulates cytoskeletal dynamics, and promotes
What the literature studies
Recovery Research
Evidence tier
Animal Only
Compounding record
Status not verified
Status not verified. Status not verified. Exact FDA substance context: FDA names thymosin beta-4 fragment LKKTETQ (TB-500): Nomination withdrawn. This record specifies Ac-LKKTETQ; the acetylated identity is not verified against that listing. Previously in Category 2; FDA still identifies potential significant safety risks for the named withdrawn substance. Withdrawal is not FDA approval or a determination of safety or compounding eligibility. Research information is not evidence of FDA approval. Approval, where applicable, is specific to a drug product, indication and route.
Regulatory source checked October 10, 2026. This compounding label is separate from the approval line above.
The marketing name 'TB4-Frag' is used interchangeably for both Ac-LKKTETQ and Ac-SDKP fragments, which have completely different mechanisms; consumers and researchers may be using
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Educational only. Not medical advice. This page does not give doses or sourcing. See the medical and editorial disclaimer.