TB-500 (Ac-LKKTETQ fragment)

Known published concerns and unanswered questions are kept separate so absence of evidence is never presented as reassurance.

Form describes the specific product; route describes how it reaches the body. These are sourced descriptions, not instructions.

No FDA-approved route exists, and FDA found no human studies by any route. Marketed injection descriptions are not evidence of a reviewed route.

Status applies to a product, formulation, route, population, and use. It does not apply to a name in the abstract.

1. Jul 22, 2026

   Research only

   No FDA-approved TB-500 product was identified. In a May 2026 staff briefing prepared for the July 23-24 advisory-committee meeting, FDA said the evaluation criteria weighed against 503A Bulks List inclusion; FDA stated that no final determination would be issued until the advisory process and reviews were complete.

   Specific form or route not separately published in this record.View source

Organize a conversation with a qualified professional without creating a treatment recommendation, dose, or protocol.

• EvidenceWhich human evidence applies to the exact product, form, route, and use being discussed?
• What remains uncertainWhat is known, and what remains uncertain for this specific context?
• RisksWhich important warnings, common effects, and product-quality concerns should be discussed?
• U.S. statusWhat does the U.S. status cover, and what does it not cover?

These profiles share a topic, pathway, product context, or research question. Related does not mean equivalent.

• Thymosin beta-4TB-500 here is an acetylated seven-amino-acid fragment and is not full-length thymosin beta-4.

1. 1

   FDA staff briefing for TB-500-related substances

   U.S. Food and Drug Administration. FDA Evaluation of TB-500-Related Bulk Drug Substances (TB-500 (Free Base) and TB-500 Acetate). Pharmacy Compounding Advisory Committee briefing document. 2026.

   U.S. Food and Drug Administration · Published May 15, 2026 · Accessed Jul 22, 2026 · Regulatory source

   Open source
2. 2

   Analytical identification of the peptide marketed as TB-500

   Esposito S, et al. Detection of a synthetic thymosin beta-4 fragment in products marketed as TB-500. Drug Testing and Analysis. 2012;4(9):733-738.

   PubMed-indexed primary study · Published Sep 1, 2012 · Accessed Jul 22, 2026 · Reference source

   Open source
3. 3

   Preclinical research on thymosin beta-4 active sites

   Sosne G, et al. Thymosin beta 4 and its active sites: anti-inflammatory, reparative, and regenerative properties. FASEB Journal. 2010;24(7):2144-2151.

   PubMed-indexed review · Published Jul 1, 2010 · Accessed Jul 22, 2026 · Systematic review

   Open source