REGULATORYRFK Jr.: 14 peptides returning to Category 1 — FDA advisory committee July 2026UPDATESemaglutide and tirzepatide compounding ended — shortage resolved Feb/May 2025REGULATORYBPC-157, TB-500, thymosin alpha-1, CJC-1295, ipamorelin: expected Category 1 reclassification pendingFDAFDA advisory committee meetings scheduled: late July 2026RESEARCHTranslational Health Research Into Vascular and Neurocognitive Effects of Weight Loss [NCT07592546]RESEARCHA Master Protocol of Multiple Agents in Adults With Metabolic Dysfunction-Associated Steatotic Liver Disease (SYNERGY-Outcomes) [NCT07165028]RESEARCHTirzepatide in the Treatment of Endometrial Cancer [NCT07605247]RESEARCHA Study of Tirzepatide (LY3298176) in Participants With Type 2 Diabetes During Ramadan [NCT06635057]RESEARCHA Study of LY3457263 Compared With Placebo in Participants With Type 2 Diabetes on a Stable Dose of Semaglutide or Tirzepatide [NCT06897475]RESEARCHA Phase 2 Study of Vosoritide in Children With Idiopathic Short Stature [NCT06382155]RESEARCHMetabolic Effects of Angiotensin-(1-7) [NCT02646475]RESEARCHMulti-Site Trial of Tirzepatide for Smoking Cessation [NCT07602699]RESEARCHEvaluation of Tirzepatide as an Adjunct to Buprenorphine for the Treatment of Opioid Use Disorder [NCT06651177]NEWSOorja, run by Acceleron veterans, launches to make new fibrosis drugsREGULATORYRFK Jr.: 14 peptides returning to Category 1 — FDA advisory committee July 2026UPDATESemaglutide and tirzepatide compounding ended — shortage resolved Feb/May 2025REGULATORYBPC-157, TB-500, thymosin alpha-1, CJC-1295, ipamorelin: expected Category 1 reclassification pendingFDAFDA advisory committee meetings scheduled: late July 2026RESEARCHTranslational Health Research Into Vascular and Neurocognitive Effects of Weight Loss [NCT07592546]RESEARCHA Master Protocol of Multiple Agents in Adults With Metabolic Dysfunction-Associated Steatotic Liver Disease (SYNERGY-Outcomes) [NCT07165028]RESEARCHTirzepatide in the Treatment of Endometrial Cancer [NCT07605247]RESEARCHA Study of Tirzepatide (LY3298176) in Participants With Type 2 Diabetes During Ramadan [NCT06635057]RESEARCHA Study of LY3457263 Compared With Placebo in Participants With Type 2 Diabetes on a Stable Dose of Semaglutide or Tirzepatide [NCT06897475]RESEARCHA Phase 2 Study of Vosoritide in Children With Idiopathic Short Stature [NCT06382155]RESEARCHMetabolic Effects of Angiotensin-(1-7) [NCT02646475]RESEARCHMulti-Site Trial of Tirzepatide for Smoking Cessation [NCT07602699]RESEARCHEvaluation of Tirzepatide as an Adjunct to Buprenorphine for the Treatment of Opioid Use Disorder [NCT06651177]NEWSOorja, run by Acceleron veterans, launches to make new fibrosis drugs

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Peptide Library

TB-500

Thymosin Beta-4 / TB4 / Tβ4

Recovery & Repair

TB-500 is a synthetic fragment of Thymosin Beta-4 (TB4), a naturally occurring 43-amino acid protein found in virtually all human and animal cells that plays a critical role in tissue repair and regeneration. Originally studied extensively in equine veterinary medicine, it has become one of the most widely researched recovery peptides in clinical and preclinical settings. Its primary applications center on wound healing, reduction of inflammation, and promotion of cellular migration to injury sites.

Mechanism of Action

Synthetic analog of thymosin beta-4. Promotes cell migration by sequestering G-actin and upregulating actin polymerization. Reduces inflammation via NF-kB modulation, promotes stem cell differentiation, and accelerates wound healing and tissue repair.

Research Protocols

For research purposes only. Not medical advice.

Research protocols use 2-5mg twice weekly for the loading phase (4-6 weeks), then 2mg weekly for maintenance. Subcutaneous injection. Some protocols use intramuscular injection near injury site.

Research Notes

Clinical Research Status

TB-500 remains investigational with no FDA approval for human use, though Thymosin Beta-4 has been studied in human clinical trials for wound healing and corneal repair. RegeneRx Biopharmaceuticals conducted Phase 2 trials on the full-length TB4 molecule for dermal and ocular indications. The synthetic fragment TB-500 (amino acids 17-23 of TB4) is widely available through research chemical suppliers.

Key Published Findings

Animal studies demonstrate significant acceleration of wound closure, hair regrowth, and cardiac tissue repair following ischemic injury. TB4 upregulates actin polymerization and promotes cellular migration, angiogenesis, and extracellular matrix deposition. Research in rodent models shows reduced scar formation and improved functional recovery from muscle tears and ligament injuries.

Safety Profile

No serious adverse events were reported in human clinical trials of Thymosin Beta-4 at therapeutic doses. Common anecdotal reports include transient head rush, lethargy at initiation, and mild irritation at injection sites. The peptide is banned by WADA under section S2 (Peptide Hormones, Growth Factors, Related Substances).

Drug Interactions & Contraindications

No well-documented drug interactions exist due to limited human clinical data. Theoretical concern exists regarding use in individuals with active cancer, as TB4's pro-angiogenic and cell migration properties could theoretically promote tumor progression. Should be avoided in individuals with known malignancies pending further safety data.

Comparison to Related Compounds

TB-500 is frequently stacked with BPC-157 in recovery protocols, with the two peptides thought to work synergistically through complementary mechanisms (systemic vs. local repair). Unlike BPC-157 which acts primarily through growth factor modulation, TB-500 works via actin sequestration and cytoskeletal reorganization. Full-length Thymosin Beta-4 is more expensive and less stable than the TB-500 fragment.

Community Observations

Most commonly dosed at 2-5mg injected subcutaneously 1-2 times per week during a loading phase, then reduced to weekly maintenance. Users frequently report improved recovery from musculoskeletal injuries within 2-4 weeks of initiation. The peptide is popular among athletes and those recovering from surgical procedures or chronic tendon injuries.

Half Life

~6-8 hours

Reconstitution

Bacteriostatic water (BAC)

Storage

Lyophilized

Refrigerate 2-8C up to 18 months.

Reconstituted

Refrigerate 2-8C. Use within 14 days.

US Legal Status

Research chemical (not FDA-approved)

Also Known As

Thymosin Beta-4TB4Tβ4

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