TB-500

The earlier profile defines TB-500 as the LKKTETQ fragment corresponding to residues 17–23 of thymosin beta-4. Full-length thymosin beta-4 contains 43 residues and has a separate profile. Findings or specifications for one must not automatically be assigned to the other.

The old route includes N-terminal acetylation and counterion discussion. The exact terminal and salt forms need to be explicit in the product specification. Its mass and CoA examples remain unverified reference material.

The described Fmoc (a temporary chemical protecting group) route assembles the protected fragment on a solid support. Coupling completion, side-chain protection and any acetylation step need their own records. A fragment may be shorter to assemble than its parent peptide, but its identity still includes the intended terminal groups.

Cleavage and deprotection release a crude mixture. The older account discusses scavengers, precipitation and recovery before purification. The technical table retains its example manufacturing sequence without turning it into a validated procedure.

Preparative RP-HPLC (reversed-phase high-performance liquid chromatography, which separates mixture components) separates target material from deletion products, altered chains and other residues. Fraction tests matter because a collection window by itself cannot confirm purity or identity. The old column and loading parameters are examples.

Desalting and counterion exchange change the non-peptide material in the powder. Freeze-drying controls water and physical form. The recovered amount should therefore be assessed using peptide content as well as total mass.

The older release panel separates identity, HPLC purity, related substances, content, water and microbiological testing. Mass should be compared with the exact fragment form being claimed. Results for a full-length peptide cannot satisfy that identity requirement.

The sample CoA and example quantity fields below illustrate document structure. They do not describe a verified batch, a clinical dose or the quality of any supplier’s product.

The earlier stability programme compares long-term, accelerated and stress conditions. The purpose is to measure chemical and physical change in a defined container. A study schedule is not a shelf-life result.

Any solution-state stability claim needs its own formulation and analytical evidence. It cannot be derived from the powder’s example retest period.

A complete record links the fragment specification, raw-material lots, synthesis history, purified fractions, drying cycle and authorised release. The certificate needs actual results, methods and a traceable batch number. Deviations and changes should remain visible in the quality record.

FDA’s page current as of April 22, 2026 lists the thymosin beta-4 fragment LKKTETQ, described here as TB-500, among substances nominated but withdrawn. Withdrawal is not approval. This statement must not be broadened into a classification of full-length thymosin beta-4.

TB-500 tables retain the earlier manufacturing examples. No TB-500 table here validates an operating procedure, release limit or supplier result. The TB-500 examples have no supporting batch raw data; use them to identify document fields, not to infer measured performance.

TB-500 source links are retained below. These references give context for TB-500 manufacturing; they do not validate the numerical examples. Duplicate TB-500 source links retain the citation record.

1. [1]
2. [2]
3. [3]
4. [4]
5. [5]
6. [6]
7. [7]
8. [8]
9. [9]
10. [10]
11. [11]
12. Bachem. "Solid Phase Peptide Synthesis (SPPS) Explained." https://www.bachem.com/articles/peptides/solid-phase-peptide-synthesis-explained/
13. Behrendt R, White P, Offer J. "Automated solid-phase peptide synthesis to obtain therapeutic peptides." PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC4077397/
14. Science Direct. "Sustainable Ultrasound-Assisted Solid-Phase peptide synthesis (SUS-SPPS): Less Waste, more efficiency." https://www.sciencedirect.com/science/article/pii/S1350417725000367
15. PubMed. "Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500." https://pubmed.ncbi.nlm.nih.gov/22962027/
16. PMC. "Recommended Best Practices for Lyophilization Validation 2021 Part II: Process Qualification and Continued Process Verification." https://pmc.ncbi.nlm.nih.gov/articles/PMC8575750/
17. PMC. "Recommended Best Practices for Lyophilization Validation—2021 Part I: Process Design and Modeling." https://pmc.ncbi.nlm.nih.gov/articles/PMC8373746/
18. International Conference on Harmonisation. "ICH Quality Guidelines." https://www.ich.org/page/quality-guidelines
19. PubMed. "Doping control analysis of TB-500, a synthetic version of an active region of thymosin β₄, in equine urine and plasma by liquid chromatography-mass spectrometry." https://pubmed.ncbi.nlm.nih.gov/23084823/
20. ICH. "Q1A(R2) Stability Testing Guidelines." https://database.ich.org/sites/default/files/Q1A(R2)%20Guideline.pdf
21. International Conference on Harmonisation. "ICH Quality Guidelines - Stability Testing." https://www.ich.org/page/quality-guidelines
22. PekCura Labs. "TB-500 - Certificates of Analysis." https://pekcuralabs.com/tb-500-certificates-of-analysis/