TB-500
Systemic tissue repair and anti-fibrotic — mobilises repair cells body-wide via actin sequestration and PI3K/Akt signalling.
Research facts
| Half-life | ~10–14 days |
|---|---|
| Route | SubQ / IM |
| Typical dose | 2–5 mg/week (loading) |
| Frequency | 2×/week loading → 1×/week maintenance |
| Solvent | Bacteriostatic water |
| pH | 5.5–7.0 |
| Stability | 30 days at +4°C |
Mechanism of action
TB-500 is a synthetic fragment of Thymosin Beta-4 (Tβ4), specifically the active region Ac-SDKP. It works primarily through actin sequestration — binding G-actin monomers to regulate actin polymerisation states, which directly promotes cell migration and proliferation throughout the body. This systemic mobility of repair cells differentiates TB-500 from more localised peptides like BPC-157.
TB-500 activates the PI3K/Akt survival pathway, driving systemic angiogenesis and reducing apoptosis in stressed tissues. The Ac-SDKP tetrapeptide (a cleavage product of Thymosin Beta-4) inhibits TGF-β1-induced collagen synthesis, giving TB-500 anti-fibrotic properties relevant to cardiac, renal, and hepatic fibrosis models. It also suppresses inflammatory cytokines including IL-1β and TNF-α.
Its systemic distribution — in contrast to BPC-157's more localised effects — makes it particularly valuable for full-body repair. The 10–14 day half-life allows once-weekly or twice-weekly dosing with stable plasma levels.
Documented effects (research-model)
- Systemic tissue repair across muscle, tendon, and cardiac tissue
- Anti-fibrotic via Ac-SDKP mechanism
- Hair follicle stimulation and regrowth research
- Cardiac protection and myocardial repair
- Wound healing and skin repair acceleration
- Immune modulation and systemic anti-inflammatory action
Research protocols
| Protocol | Dose | Frequency | Cycle | Vial |
|---|---|---|---|---|
| Loading | 2 mg × 2/week | Twice weekly SubQ | 4–6 week loading phase | 5mg / 2mL BAC water |
| Maintenance | 2 mg/week | Once weekly | Ongoing after loading | 5mg / 2mL BAC water |
Research context only. Not medical advice. Consult a qualified healthcare professional before any protocol decision.
Synergies
- BPC-157 HIGH
The Wolverine Stack — TB-500 provides systemic cell mobilisation; BPC-157 delivers localised vascular and nerve repair. The gold standard healing combination. - GHK-Cu HIGH
TB-500 mobilises repair cells; GHK-Cu provides the collagen matrix they need to reconstruct tissue at repair sites. - SS-31 MODERATE
Mitochondrial energy restoration (SS-31) + structural vascular repair (TB-500) for organ-level recovery.
Myths & misconceptions
Evidence gaps
- No completed human RCTs. All efficacy data derives from animal models and some Phase I safety studies.
- Cardiac repair potential is promising in murine MI models but has never been validated in human cardiac trials.
- Whether the Ac-SDKP anti-fibrotic effect operates at research doses in humans is unverified.
Safety notes
Considered safe in animal models. Systemic distribution warrants monitoring general inflammatory markers. TB-500 was removed from FDA Category 2 restricted list in April 2026.
Biomarkers to monitor
Primary-source citations
- PMID 15592671 — Thymosin beta4 facilitates efficient repair of injured adult skeletal muscle (Ann N Y Acad Sci. 2004)
- PMID 22616897 — Thymosin beta-4 is cardioprotective after myocardial infarction (Ann N Y Acad Sci. 2012)
Frequently asked
What is TB-500?
TB-500 (Thymosin Beta-4 Fragment Tβ4(17-23)) is a research compound classified in our library as Tier C — Limited human trials; effect size uncertain.. Systemic tissue repair and anti-fibrotic — mobilises repair cells body-wide via actin sequestration and PI3K/Akt signalling.
What is the evidence tier for TB-500?
We classify TB-500 as Tier C: Limited human trials; effect size uncertain. See our full peptide evidence tiers explainer for how we assign S/A/B/C/D.
What is the research dose of TB-500?
For TB-500, typical research dose is 2–5 mg/week (loading), route is SubQ / IM, half-life is ~10–14 days. Protocols vary by research goal — see the protocols section on this page for standard and advanced dosing schedules. Research use only, not medical advice.
What does TB-500 stack well with?
TB-500 stacks well with BPC-157. The Wolverine Stack — TB-500 provides systemic cell mobilisation; BPC-157 delivers localised vascular and nerve repair. The gold standard healing combination.
Is TB-500 safe?
Considered safe in animal models. Systemic distribution warrants monitoring general inflammatory markers. Research context only — no compound on this site is approved for human therapeutic use unless explicitly noted.