RECOVERY · Injectable
TB4 (Thymosin Beta 4).
Full-length 43-AA regenerative peptide — parent molecule of TB-500
How it works
Class & mechanism.
In short
TB-4 (Thymosin Beta-4) is the naturally occurring 43-amino-acid protein that TB-500 is a fragment of. Found in nearly every cell, it regulates actin — the scaffolding cells use to move — and is studied for wound healing, angiogenesis, and reduced scarring. As the full-length parent molecule, it may engage a broader set of repair pathways than the TB-500 fragment, though most evidence is preclinical.
Class
Thymosin Beta Peptide
Mechanism
Thymosin Beta 4 (TB4) is a naturally occurring 43-amino acid peptide (MW ~4,964 Da) present in virtually all mammalian cells, with highest concentrations in platelets, neutrophils, macrophages, and wound fluid. It is the full-length parent molecule from which the synthetic fragment TB-500 (amino acids 17-23) is derived. TB4's primary mechanism is actin sequestration — it binds G-actin monomers in a 1:1 complex, regulating actin polymerization essential for cell migration, wound closure, and tissue regeneration. Beyond actin, TB4 promotes angiogenesis, downregulates inflammatory cytokines (TNF-α, NF-κB), recruits stem/progenitor cells to injury sites, and upregulates MMPs for extracellular matrix remodeling. It also reduces scar formation by modulating the collagen I:III ratio — promoting regenerative rather than fibrotic repair.
Personalized Peptides provides DNA-driven peptide recommendations — we are not a compounding pharmacy, peptide synthesis company, or clinical provider.
Did you know
TB-500 — the fragment most peptide users know — is only 7 amino acids long. TB4, the complete parent molecule, is 43 amino acids. It's like comparing a single piano key to the full keyboard. The fragment engages one pathway; the full molecule orchestrates the entire regenerative symphony — actin remodeling, angiogenesis, stem cell recruitment, inflammation modulation, and collagen ratio optimization — all at once.
Preclinical Data
No human PK studies available.
Limited human PK — topical Phase I/II data only. No systemic PK published.
Class
Endogenous 43-AA G-actin sequestering protein
Route
SC / IM / Topical
Mol. Weight
4,964 Da
What we don't know
RegeneRx conducted Phase I/II trials for dry eye (topical), venous stasis ulcers, and cardiac applications using full recombinant TB-4 (RGN-352), confirming safety and tolerability but not publishing detailed systemic PK. No formal PK parameters (Vd, CL, absolute bioavailability) are publicly available for any route.
Why this dosing protocol
Weekly dosing is supported by the sustained nature of actin-mediated tissue remodelling and the large endogenous reservoir (100-500 µM intracellular) that dominates PK. Exogenous TB-4 likely acts as a signalling pulse rather than sustained replacement therapy. Topical formulations (eye drops) are supported by Phase II data for dry eye/corneal healing. Systemic protocols mirror TB-500 dosing patterns.
Empirical protocol: 5-10mg SC 1-2×/week; 50-200mcg topical (eye drops)
Safety notes
- No systemic human PK data
- Endogenous reservoir dominates kinetics
Pharmacokinetic data shown for educational context. All parameters are inferred or empirically derived — no formal human PK studies exist for this compound. Individual response varies. Not a substitute for clinical dosing guidance.
Benefits
What it does.
Full-length regenerative signalling — as the complete 43-AA parent molecule, TB4 may engage the full spectrum of actin-binding, angiogenic, and anti-inflammatory pathways that the TB-500 fragment only partially covers
Scarless healing — preclinical evidence suggests TB4 may shift the collagen I:III ratio toward regenerative repair rather than fibrotic scarring
Angiogenesis and wound closure — may promote new blood vessel formation and accelerate cell migration to wound sites
Anti-inflammatory cascade — may downregulate TNF-α and NF-κB while promoting anti-inflammatory macrophage polarization
Stem cell recruitment — may help mobilize endogenous stem and progenitor cells to sites of injury
The science
Peer-reviewed findings.
Research supporting this compound's mechanisms and safety profile.
What this does not mean
TB-4 (Thymosin Beta-4) is a research chemical. The information on this page is educational and does not constitute medical advice, diagnosis, or treatment. TB-4 is not FDA-approved for treating wounds, tissue damage, or any other use. This page does not recommend, endorse, or prescribe any compound for human use. Always consult a qualified healthcare provider before making health decisions. Personalized Peptides provides DNA-driven educational context and test interpretation — not clinical protocols or pharmaceutical recommendations.
TB4 is one of the most extensively studied regenerative peptides, with hundreds of peer-reviewed publications across wound healing, cardiac repair, neuroprotection, and ophthalmology — far exceeding the fragment TB-500 in published preclinical evidence
SOURCE · Goldstein AL et al., multiple publications; extensive wound healing, cardiac, and neurological repair literature
Protocol
How to use it.
Dosing
Typical protocols: 2.5–5 mg subcutaneous injection, 2–3× per week. Higher doses (5–10 mg) used in acute injury protocols. Local injection near injury site or systemic abdominal SQ.
Cycle
4–8 weeks for acute injury; 8–12 weeks for chronic conditions. Rest periods of 4–6 weeks between cycles. No established long-term human cycling data.
Contraindications
When to skip it.
No human-approved dosing guidelines. Theoretical concern around angiogenesis in active/undiagnosed cancers. Banned by WADA for competitive athletes. Use under physician supervision only.
Always cleared with your concierge before protocol start.
Regulatory Context
FDA compounding status.
| FDA Status | Risk Level | Compounding | Key Date |
|---|---|---|---|
| Related to TB-500 (PCAC Review July 2026) | 🔴 At Risk | Awaiting PCAC — regulatory posture tracks TB-500 | PCAC July 23, 2026 |
Thymosin Beta 4 — full-length 43-AA parent molecule of TB-500. Regulatory status tracks TB-500 (fragment). Both removed from Cat 2 Apr 23, under PCAC review.
Source: FDA Federal Register, PCAC agendas, industry analyses. Educational context only — not legal advice. Review after July 23-24, 2026 PCAC meeting.
Pricing
What it costs.
Indicative range for TB4 (Thymosin Beta 4), sourced from vetted US and EU dispensing suppliers. Concierge confirms the exact figure once your match is locked.
Indicative range (USD)
Sourced through vetted dispensing partners in the United States and European Union. Concierge confirms the exact figure once your match is locked.
- 0199% purity verified, third-party tested
- 02Includes vial and reconstitution guidance
- 03Concierge supplier match included with every protocol
See TB4 (Thymosin Beta 4) pricing — and your supplier match.
Pricing is unlocked once we know who you are. Take the 3-minute quiz and we'll match you to a US or EU dispensary based on your location and protocol fit.
- Live USD price range
- US & EU supplier shortlist
- Concierge sign-off on dosing
Indicative price range: $124–$186 USD