Healing & Recovery

TB-500

Ac-LKKTETQ · Tβ4 fragment 17–23 · TB500

Synthetic N-acetyl heptapeptide (Ac-LKKTETQ) matching thymosin β4 residues 17–23, the actin-binding loop. Research-chem SKU is this fragment (~889 Da), not the 43-aa parent (~4963 Da) that has the human trial record. WADA S0. Not approved for human use.

Not FDA-approved - research chemicalWADA (S0) - prohibited in sport at all times

Reviewed by CalcMyPeptide Editorial Team

·Last updated: August 2026·Evidence: Low·5 peer-reviewed citations

Typical research dose

2-5 mg twice weekly

Frequency

2× weekly (loading), 1× weekly (maintenance)

Half-life

Not established in humans for the 7-mer

Common vials

5 mg / 10 mg

CAS

885340-08-9

Molecular weight

889.02 g/mol

Use-case scores

0–10 against the evidence we have, not a gym ranking. Hidden domains do not apply here.

Injury & tissue3.5/10
Actin-loop biochemistry plus parent Tβ4 animal repair models. Haircut because the commercial SKU is the 7-mer, and the 7-mer has no completed human efficacy trial.
Recovery & sleep3/10
Used in community recovery stacks, often with BPC-157. Not a sleep peptide. Community ceiling.
Muscle / recomp2.5/10
Cell-migration and actin stories get stretched into hypertrophy. Mechanism only for the fragment. Parent cardiac programs are not this vial.

Compound card

Sequence: Ac-LKKTETQ (Tβ4 residues 17–23)
Class: Synthetic N-acetyl heptapeptide fragment of thymosin β4
Formula: C38H68N10O14
Status: Not FDA-approved · research use

Dose it

5 mg + 2 mL BAC water → 2.5 mg/mL · 2000 mcg ≈ 80 units (U-100)

Open in calculator

How it works

TB-500 as sold is almost always Ac-LKKTETQ, a 7-residue N-acetyl fragment matching thymosin β4 positions 17–23 (the actin-binding loop). Formula C38H68N10O14, about 889 Da, CAS 885340-08-9. It is not the 43-amino-acid parent protein (CAS 77591-33-4, about 4963 Da). Full-length Tβ4 has the clinical program (RGN-259 / RGN-352 and related). The fragment has the research-chem SKU and the equine doping-control papers.

Crockford 2010 mapped LKKTETQ as the actin-binding motif on the parent. That biochemistry is real. It does not mean every wound, cardiac, or corneal trial of full Tβ4 transfers to a 7-mer vial. Parent Tβ4 sequesters G-actin and shows up in angiogenesis and cell-migration models. The fragment covers the loop. It does not automatically cover the rest of the 43-mer.

Do not inject this leaf as if it were thymosin β4. The library has a separate full-length page. WADA treats TB-500 as S0 by analogy to the parent.

Source: PMID: 20514133, PMID: 23084823

Fragment in the vial, parent in the papers

Commercial TB-500 is Ac-LKKTETQ (~889 Da). Full thymosin β4 is 43 amino acids (~4963 Da) and is the molecule in the human trial record. Ask for the sequence on the COA. Do not dose this page as RGN-259.

Goal context

Soft-tissue recovery (the search)

People buy TB-500 for tendons and muscle because the parent protein’s repair story is decades old. Equine use and doping-control methods are well documented. Human efficacy for Ac-LKKTETQ is not. Treat loading-phase calendars as community practice.

Full Tβ4 vs this SKU

Full-length thymosin β4 reached human trials in eye, skin, and heart indications. Several late-stage programs missed primary endpoints. None of that is a 2–5 mg twice-weekly 7-mer protocol. If you meant the 43-mer, use the thymosin beta-4 leaf.

Stacking with BPC-157

The pair is the default research-chem recovery blend. Complementary marketing (actin vs VEGF) is not a synergy RCT. Math both vials. Do not dose a mixed bottle as if it were one molecule.

Background & History

TB-500 as sold is the synthetic N-acetyl heptapeptide Ac-LKKTETQ (thymosin β4 residues 17–23), CAS 885340-08-9, about 889 Da. Full-length thymosin β4 is a 43-aa protein with a separate CAS and the human trial record. The fragment showed up in equine doping-control work (Ho 2012) because it was already in sport, not because it had a human repair label. Do not launder RGN-259 or cardiac Tβ4 trials onto this SKU.

Research Use Cases

✓Community recovery stacks, often with BPC-157
✓Equine doping-control literature (detection of Ac-LKKTETQ), not a human indication
✓Actin-loop biochemistry research; not a substitute for full-length Tβ4 trials

Dosing

Phase	Dose	Frequency	Notes
Loading (community)	2–5 mg	Twice weekly SubQ, 4–6 weeks	Research-chem calendar. Site-specific injection is not required because the 7-mer is small; that is not the same as proven systemic repair.
Maintenance (community)	2 mg	Once weekly SubQ	Sometimes split 1 mg twice weekly. Not a labeled taper.

Administration

Route / form

Subcutaneous injection from a reconstituted lyophilized vial. Confirm the COA says Ac-LKKTETQ, not 43-aa Tβ4.

Timing

Any consistent time. Fasting is not required. Injury-site injection is optional, not a PK law.

Empty stomach?

No - Food timing is not critical.

Preparation

Best injection sites

Abdomen, Thigh, Upper arm

Required supplies

Lyophilized vial
Bacteriostatic water
U-100 insulin syringes
Alcohol swabs
Sharps container

Storage

Before reconstitution

Lyophilized powder refrigerated 2–8 °C, protected from light.

After reconstitution

Reconstituted solution refrigerated 2–8 °C. Typical BAC-water window is up to 28 days if sterility holds.

Signs of degradation

Cloudiness • Particles • Color change

Timeline

Weeks 1–2

Anecdotes talk about comfort. There is no fragment RCT to time this.

Weeks 3–6

Community loading phase. Mobility claims are logs, not endpoints.

After loading

Some protocols drop to weekly maintenance. That is habit, not a label.

Who it is for

Research-chem recovery stacks

Moderate

This is how the SKU is used. Evidence is community plus parent-protein extrapolation.

Full-length Tβ4 clinical indications

Low

Wrong molecule. Use the thymosin beta-4 leaf and read which trial actually dosed the 43-mer.

Hypertrophy / recomp

Low

Actin motility is not a muscle-gain trial.

Reconstitution

Vial	Water	Concentration	Example dose
5 mg	2.0 mL BAC	2.5 mg/mL	2.5 mg = 1.0 mL = 100 units on a U-100 syringe
10 mg	2.0 mL BAC	5 mg/mL	2.5 mg = 0.5 mL = 50 units on a U-100 syringe

Change vial size or water volume? Open the reconstitution calculator.

Safety & Considerations

Research-use 7-mer. Not FDA-approved. Not the Tβ4 clinical candidate. Angiogenesis signaling is why active cancer is a hard no. Equine doping-control literature exists because this fragment showed up in sport, not because it has a human repair label. Sterile reconstitution still matters. WADA S0.

Regulatory & Legal Status

FDA Status (US)

Research Only

WADA Status (2026)

Prohibited (S0)

Competitive athletes subject to anti-doping controls should not use TB-500.

Classification

Research Chemical

US Compounding: Not eligible / not available

⚠️ This information is for educational purposes only and may not reflect the most current regulatory updates. Always verify with official FDA, WADA, and jurisdiction-specific sources before use.

Limits of current evidence

No completed published human RCT of isolated Ac-LKKTETQ for musculoskeletal repair.
Human Tβ4 programs studied the 43-mer. Those results do not transfer automatically to the fragment.
Human PK, half-life, and bioavailability for the 7-mer are not established. Do not print 12–24 hours as if it were a label.
The indexed fragment literature is heavy on equine detection methods, light on efficacy.
Angiogenesis signaling is a caution in active malignancy, same as other repair peptides. WADA S0.

Human evidence

Low · fragment SKU without completed human efficacy RCT

No completed published human RCT of isolated Ac-LKKTETQ for musculoskeletal repair.
Human Tβ4 programs studied the 43-mer. Those results do not transfer automatically to the fragment.
Human PK, half-life, and bioavailability for the 7-mer are not established.

Verdict

TB-500 is the actin-loop fragment, not thymosin β4. Use it only if you know you have Ac-LKKTETQ in the vial, with reconstitution math you can check. Do not launder RGN-259 or cardiac Tβ4 trials onto a 7-mer. The biochemistry of the loop is the honest core. The human repair claim for this SKU is not.

Interactions & Contraindications

Angiogenesis and cell-migration signaling: stay out if there is active malignancy. No adequate human DDI package for the 7-mer.

Synergies & Common Stacks

+ BPC-157 →

Classic research-chem pair. Two molecules, two reconstitution tables. Complementary stories are not a synergy RCT.

+ IGF-1 LR3 →

Sometimes stacked in hypertrophy folklore. Parent Tβ4 cell-migration papers do not make this a combination trial.

TB-500 vs. BPC-157

Canonical comparison: TB-500 vs BPC-157

Attribute	TB-500	BPC-157
Mechanism	Actin-loop fragment (Ac-LKKTETQ)	VEGF/NO + FAK-paxillin (15-mer)
Injection	Any SubQ site is typical	Near injury is the habit, not a law
Dose	2–5 mg 2× weekly (community loading)	250–500 mcg 1–2× daily
Best For	Community recovery stacks	Local soft-tissue research protocols
WADA Status	Prohibited (S0)	Prohibited (S0)

Verdict: Not interchangeable. TB-500 as sold is usually the 7-mer fragment. BPC-157 is a 15-mer with better-characterized (still preclinical) tissue papers. Stack both only if you math both vials.

Appears in goal guides

Goal guides are maps, not clinic protocols. A mention here is not a treatment plan.

Advanced Injury Healing

BPC-157 plus TB-500 (Ac-LKKTETQ fragment) reconstitution math used in research-chem injury logs. Animal tendon papers are not a human regeneration label.

View Protocol →

Post-Surgical Accelerated Healing

BPC-157, TB-500, and GHK-Cu as they show up next to surgery folklore. Not a substitute for surgical aftercare and not a proven scar-erasure protocol.

View Protocol →

Ultimate Athletic Performance

Muscle and vascular cytomax plus BPC-157/TB-500 and GH secretagogues as they show up in athletic folklore. Injectable repair peptides are WADA-prohibited. This is not a doping pass.

View Protocol →

Frequently Asked Questions

Is TB-500 the same as thymosin β4?▼

No. TB-500 as sold is usually Ac-LKKTETQ (residues 17–23). Thymosin β4 is the 43-aa parent. Different CAS, different mass, different evidence. See the thymosin beta-4 leaf for the parent.

What is a typical research-chem dose?▼

Loading: 2–5 mg SubQ twice weekly for 4–6 weeks. Maintenance: 2 mg once weekly. Community practice, not a label.

How do I reconstitute a 5 mg vial?▼

Add 2.0 mL bacteriostatic water for 2.5 mg/mL. A 2.5 mg dose is 1.0 mL, which is 100 units on a U-100 syringe. Use the calculator if you change water volume.

Do I have to inject at the injury?▼

No. The 7-mer is small and is usually given anywhere SubQ. That is not proof of systemic repair. It is just how the SKU is used.

Does it have human trials?▼

Not for the isolated fragment as of the last review of this page. Parent Tβ4 has human programs; several late-stage readouts missed primary endpoints. Do not paste those onto TB-500.

Can I stack it with BPC-157?▼

That is the default research-chem pair. Two molecules, two reconstitution tables. Use the blend calculator. There is no synergy RCT.

Is the half-life 12–24 hours?▼

That number is not a published human 7-mer PK. This page does not print it as fact.

Is it FDA-approved?▼

No. Research chemical. WADA S0. Check the regulatory panel.

Cancer caution?▼

Angiogenesis and cell-migration signaling are the reason active malignancy is off the table. There is no fragment oncology trial either direction.

How should I store it?▼

Lyophilized vial refrigerated and dark. After BAC water, 2–8 °C. Discard if cloudy or particulate.

References

Crockford D, Turjman N, Allan C, Angel J “Thymosin beta-4: structure, function, and biological properties supporting therapeutic potential.” Annals of the New York Academy of Sciences (2010). PMID: 20514133
Ho EN, Kwok WH, Lau MY, et al. “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.” Journal of Chromatography A (2012). PMID: 23084823
Malinda KM, et al. “Thymosin beta-4 promotes dermal healing.” J Invest Dermatol (1999). PMID: 10469329
Bock-Marquette I, et al. “Thymosin β4 and cardiac repair.” Nature (2004). PMID: 15229613
Srivastava D, et al. “Thymosin beta-4 activates integrin-linked kinase and promotes cardiac cell migration, survival, and cardiac repair.” Ann N Y Acad Sci (2007). PMID: 17911436

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