TB-500

TB-500 is a synthetic peptide that functions as a fragment of the naturally occurring thymosin beta-4 (T$\beta$4) protein. It is used primarily to accelerate healing, reduce inflammation, and promote tissue regeneration. It mimics the active region of Thymosin Beta-4, a protein that regulates cell movement and healing.

Key Benefits

• May support faster recovery of muscles, tendons, and connective tissues
• Commonly researched for wound healing and injury recovery support
• May help improve flexibility, mobility, and tissue repair processes
• Research suggests potential benefits for reducing inflammation and supporting physical recovery after intense activity

FDA-Approved Uses

Regulatory status (as of May 2026):

• Currently: FDA Category 2 bulk drug substance — 503A/503B compounding technically still prohibited
• April 15–22, 2026: HHS Secretary announced intent to reclassify 14 peptides including TB-500 from Category 2 to Category 1. Formal FDA rulemaking NOT yet complete as of May 2026.
• PCAC review scheduled July 23–24, 2026 at FDA White Oak Campus
• Until formal rule is published: Category 2 prohibition technically remains in effect
• WADA 2026 Prohibited List: S2.3 — ‘Thymosin-β4 and its derivatives e.g. TB-500’ — prohibited at all times. Detection via LC-MS/MS.

Conditions studied in preclinical/animal research (NOT in human RCTs for TB-500):

• Soft tissue injury repair: Muscle, tendon, and ligament healing
• Wound healing / skin repair
• Cardiac tissue repair post-myocardial infarction (animal models)
• Neuroprotection: TBI and stroke recovery (animal models)
• Dry eye / corneal healing (full-length TB4 — RGN-259 — Phase 2 data; not TB-500 directly)
• Hair follicle regeneration
• Angiogenesis and vascular repair

TB-500 is a fragment of Thymosin Beta-4 (TB4). The strongest human clinical data exists for full-length TB4 (RGN-259 by RegeneRx), NOT for injectable TB-500 specifically. These are related but distinct compounds.

Trade Names in the USA and Manufacturers

Related compound with human clinical data (NOT TB-500):
RGN-259 (full-length Thymosin Beta-4, topical eye drops) — RegeneRx Biopharmaceuticals
Completed Phase 2 trials for dry eye and corneal injury. Phase 3 not yet completed.

TB-500 US availability (as of May 2026)

Formally still Category 2 (compounding prohibited until formal rulemaking completed)
Grey-market research peptide vendors: Widely available (‘research use only’)
After formal Category 1 reclassification: Licensed 503A pharmacies with valid prescription

Molecular identity

• Synthetic heptapeptide fragment of Thymosin Beta-4 (amino acids 17–23)
• Active sequence: Ac-LKKTETQ (N-terminally acetylated)
• Leu-Lys-Lys-Thr-Glu-Thr-Gln with N-terminal acetylation
• MW: ~963 Daltons
• Distinct from full Thymosin Beta-4 (43 amino acids, MW ~4,921 Daltons)
• Half-life: ~2–4 days (vs ~2 hours for native TB4; acetylation improves stability)

Often combined with BPC-157 in the ‘Wolverine Stack’

Dosage

All protocols reflect community research use only.

LOADING PHASE (Weeks 1–6)

• Dose: 2–2.5 mg per injection
• Frequency: 2x weekly (e.g., Monday + Thursday)
• Route: Subcutaneous (SC) or Intramuscular (IM)
• Duration: 4–6 weeks

MAINTENANCE PHASE

• Dose: 2–2.5 mg per injection
• Frequency: 1x weekly
• Route: SC or IM

Alternative low-dose protocol:
1 mg SC twice weekly

Reconstitution

• Lyophilized powder (2 mg, 5 mg, 10 mg vials)
• Reconstitute with 1–2 mL Bacteriostatic Water for Injection
• Store lyophilized at -18°C or below
• Reconstituted solution: refrigerate (2–8°C); use within 7–14 days

Injection site

• SC: Abdomen for systemic effects
• IM: Near injury site for localized repair (some protocols)

Combination Wolverine Stack

• TB-500: 2–2.5 mg SC, 2x/week
• BPC-157: 250–500 mcg SC, daily
• [BPC-157 remains FDA Category 2 — verify status before use]

Pricing

No FDA-approved commercial pricing.

Research peptide vendors

• 2 mg vial: ~$15–$35
• 5 mg vial: ~$30–$60
• 10 mg vial: ~$50–$90
• Monthly (loading, 2.5 mg x2/week): ~$100–$250/month
• Monthly (maintenance, 2.5 mg x1/week): ~$50–$120/month

After Category 1 reclassification (pending July 2026):
Compounded from licensed 503A pharmacy: estimated ~$150–$400/month

⚠️ Always request third-party Certificate of Analysis (CoA) confirming purity ≥98%. Cold-chain shipping required.

Tips

• Monitor July 23–24, 2026 PCAC meeting outcome — determines formal Category 1 reclassification enabling licensed 503A pharmacy access.
• WADA S2.3 PROHIBITED: ‘Thymosin-β4 and its derivatives e.g. TB-500’ — banned at all times. No TUE available. LC-MS/MS detection possible for extended period.
• The strongest human data is for RGN-259 (topical full-length TB4, not injectable TB-500). Do not conflate these two distinct compounds when evaluating evidence.
• Pro-angiogenic mechanism: TB-500 promotes VEGF expression and angiogenesis. Anyone with active or recent malignancy should avoid — theoretical concern about promoting tumor vascularization.
• Request CoA with third-party mass spectrometry before using any research TB-500. Peptide impurities and underdosed vials are documented grey-market concerns.
• TB-500 and BPC-157 work through complementary mechanisms. The Wolverine Stack is based on synergy — but neither has human RCT data for musculoskeletal injuries.
• Store lyophilized product at -20°C or below. Do not accept or use product shipped without cold-chain packaging.

Side Effects

⚠️ Limited human safety data. TB-500 itself has no completed human clinical RCTs.

Best available human reference:
– Phase 1 RCT (Goldstein et al., 2010): 40 healthy adults; IV full-length TB4 (not TB-500) at 42–1,260 mg.
Generally well-tolerated; adverse events uncommon, mild-to-moderate; no serious drug-related events.
[Much higher doses than typical TB-500 community use; different molecule]

Commonly reported in off-label community use:
– Injection site reactions: Pain, redness, swelling, bruising (mild, transient)
– Headache (mild; shortly after injection)
– Fatigue/lethargy (transient; typically first 24–48 hours)
– Nausea (mild; uncommon)
– Lightheadedness or dizziness
– Flushing or warmth (brief)

Theoretical concerns from mechanism:
– Pro-angiogenic risk: VEGF upregulation — theoretical tumor vascularization concern in patients with malignancy; no confirmed human cases but risk cannot be excluded
– Immunological reactions: Antibody formation possible with repeated dosing

⚠️ Long-term human safety is entirely unknown. No chronic toxicology studies exist in humans for TB-500.

Contraindications

No formal FDA contraindications (no approved label).

Based on mechanism and preclinical data:

Avoid:
– Active malignancy or cancer history: Pro-angiogenic (VEGF upregulation) — theoretical tumor vascularization risk
– Athletes subject to WADA/USADA: Prohibited S2.3 at all times — absolute contraindication
– Pregnancy and breastfeeding: No safety data

Use with caution:
– Cardiovascular disease or recent MI: Angiogenic effects may have unpredictable vascular consequences
– Autoimmune conditions: Thymosin peptides are immunomodulatory — possible interaction
– Patients on immunosuppressants: Potential immune-modulating interaction
– Children: No safety data
– Hypersensitivity to TB-500 or components

Pharmacology

TB-500 is a synthetic 17-amino acid N-terminal fragment of Thymosin Beta-4 (Tβ4), with the biologically active core sequence being LKKTETQ (7 amino acids, positions 17–23 of full TB4). N-terminal acetylation (Ac-LKKTETQ) enhances enzymatic stability and biological activity. MW ~963 Daltons.

Parent protein — Thymosin Beta-4 (TB4):
– 43-amino acid peptide; MW ~4,921 Daltons
– One of the most abundant intracellular proteins in mammalian cells
– Found in blood, tears, cerebrospinal fluid, and wound fluid
– Concentrations increase significantly at sites of tissue injury — TB4 is a key endogenous tissue repair signal

Distinction from full TB4:
– TB-500 is NOT identical to full Thymosin Beta-4 (RGN-259)
– Contains the active actin-binding region but lacks additional structural/functional domains of full-length protein
– Half-life: ~2–4 days (vs ~2 hours for native TB4)
– Acetylation further increases stability

Formulation: Lyophilized powder; reconstituted with Bacteriostatic Water; store at -20°C lyophilized; stable in solution 7–14 days at 4°C.

Mechanism of action

1. Actin Binding / Sequestration (primary mechanism):
LKKTETQ sequence binds G-actin (globular monomeric actin), sequestering it.
Effect: Increases available G-actin pool → promotes cell shape changes and migration.
Cells (fibroblasts, endothelial cells, keratinocytes, stem cells) can move more readily to injury sites.

2. Promotion of Cell Migration:
Stimulates migration of:
– Fibroblasts → collagen deposition
– Endothelial cells → angiogenesis
– Keratinocytes → re-epithelialization
– Stem/progenitor cells → tissue regeneration

3. Angiogenesis via VEGF Upregulation:
Upregulates VEGF → promotes new blood vessel formation → improved oxygen/nutrient delivery to healing tissue.

4. Anti-Inflammatory Effects:
Downregulates TNF-α, IL-1β at injury sites — reduces swelling, pain, secondary damage.

5. Upregulation of Total Actin Expression:
Increases total cellular actin levels — provides more structural material for repair.

6. Neuroprotection (animal models):
Promotes neuronal survival and functional recovery via anti-apoptotic and angiogenic pathways.

Result Claims from Different Companies

RegeneRx Biopharmaceuticals (full-length TB4, RGN-259 — NOT TB-500):
– Phase 2 ARISE trials (topical eye drops, dry eye): Significant improvement in ocular pain and fluorescein staining vs. placebo; well-tolerated
– Phase 2 (corneal injuries): Significant improvement in corneal healing rate vs. placebo
– Pilot study (Zhu et al., Cytotherapy, 2016): TB4 pre-treated EPC transplantation in acute MI — improved cardiac function parameters (small pilot study)

Academic research (TB-500 specifically; animal models):
– Multiple independent laboratories: TB-500 significantly accelerated muscle, tendon, and cardiac tissue repair in rodent injury models
– Consistent VEGF upregulation and angiogenic effects across multiple tissue types
– Anti-inflammatory effects confirmed in wound healing models

⚠️ ALL TB-500 injection efficacy data is from animal studies. No completed human RCTs for injectable TB-500 exist. The human clinical data (RGN-259) is for topical full-length TB4 — not injectable TB-500. WADA prohibition applies at all times.

Disclaimer

This content about “TB-500” is for informational and educational purposes only, is not medical advice, does not replace consultation with a licensed healthcare professional, and affiliate links may result in compensation at no additional cost to you.