TB-500 Reconstitution Calculator
TB-500 is sold as the 17-23 fragment of thymosin β4 — the seven-residue sequence LKKTETQ — and arrives as a lyophilised powder that must be reconstituted with bacteriostatic water. Vials are commonly listed at 2 mg, 5 mg or 10 mg, so the volume of water added is what sets the concentration. This calculator converts a vial size and a mixing volume into mg/ml and U-100 syringe units. It does not tell you what to inject: no human study of the marketed TB-500 fragment has ever been published, so there is no established dose to prefill.
No established human dose
No human trial has established a dose for TB-500. There is no evidence-based dose to give, and this page does not give one.
The calculator below converts a vial size and a mixing volume into a concentration. That is arithmetic about the vial, not a recommendation about what to inject.
What the evidence says
No human study of TB-500 as sold has been published. TB-500 is the thymosin β4 17-23 fragment; a 2026 sports-medicine review lists 'Tβ4 (thymosin beta-4)' and 'TB-500 (thymosin beta-4 fragment)' as two separate compounds (PMID 41966639), and the one registered TB-500 study titles the intervention 'Thymosin Beta 4 17-23 Fragment' (NCT07487363, recruiting, not reported).
That distinction is the whole difficulty here, because full-length synthetic thymosin β4 does have real human trials and their doses are routinely misattributed to TB-500: • Phase 1, randomised, placebo-controlled: four cohorts of 10 healthy volunteers given single then daily 14-day INTRAVENOUS doses of 42, 140, 420 or 1260 mg (PMID 20536472). Well tolerated with no dose-limiting toxicity — but these are intravenous milligram loads two to three orders of magnitude above the 2-5 mg subcutaneous figure vendors list. • First-in-human Phase 1 of recombinant human thymosin β4 (NL005): 54 subjects single-dose at 0.05-25 µg/kg intravenously and 30 subjects dosed daily for 10 days at 0.5, 2.0 or 5.0 µg/kg (PMID 34346165). Note this second phase 1 sits three orders of magnitude BELOW the first — the two human programmes do not even agree with each other on scale. • Phase 2 topical: 0.03% gel in venous stasis ulcers (73 patients randomised, PMID 20536470; design paper PMID 17495250) and 0.1% RGN-259 eye drops six times daily in severe dry eye (9 patients, PMID 25826322). • A randomised trial of recombinant thymosin β4 in 96 STEMI patients after PCI reported a reduced infarct area in the treated arm but no significant overall difference (PMID 41229390).
None of these is subcutaneous, none is the marketed fragment, and neither an intravenous milligram load nor a topical percentage converts into a subcutaneous dose. The remaining dose figures in the literature are animal: e.g. an optimal 3.75 mg/kg estimated from a rat embolic-stroke dose-response study (PMID 25060418). No number in this entry is derived from any of them.
evidence_level is recorded as animal_only because nothing has been published on the molecule this entry names in humans; the human trials above belong to a different molecule and are listed here precisely so they are not mistaken for TB-500 evidence.
TB-500 at a glance
- Category
- Healing peptide
- Half-life
- Not established
- Routes
- Subcutaneous, Other
- Regulatory status
- Research use only
- Also sold as
- TB 500, thymosin beta-4 fragment, Tβ4 17-23 fragment, LKKTETQ
Mechanism
TB-500 is the 17-23 fragment of thymosin β4 (the sequence LKKTETQ), the region held to carry the parent protein's actin-binding activity. Reviews and trial registrations treat it as a distinct entity from full-length thymosin β4, a 43-amino-acid actin-sequestering protein. Thymosin β4 itself binds G-actin and regulates actin polymerisation, and in animal and cell models promotes endothelial and keratinocyte migration, angiogenesis, collagen deposition and anti-inflammatory signalling; it is essential for coronary vessel development and stimulates outgrowth from adult epicardium. Whether the 17-23 fragment reproduces those actions at the tissue level in a living human has not been tested — the fragment's mechanistic claims are inherited from the parent protein rather than demonstrated for the fragment.
Reconstitution
Requires reconstitution with bacteriostatic water. Vials are commonly sold at 2 mg, 5 mg or 10 mg, and the listed protocols are ambiguous about whether a stated milligram figure is per injection or per week — reconstituting to a concentration that assumes the wrong one changes weekly exposure by 2-5x. Confirm which the source meant before drawing anything up.
Storage
Supplied as a lyophilised powder. No approved product exists, so there is no manufacturer stability data or validated shelf life; vendor guidance to refrigerate sealed vials and use reconstituted material within a few weeks is convention, not tested stability.
Frequency in practice
No established regimen exists. Vendors and clinics describe a loading phase of two injections a week for 4-6 weeks followed by weekly maintenance; the published human trials of the parent protein used daily intravenous infusion or several-times-daily topical application instead, so the weekly pattern has no trial basis.
Regulatory
Not approved by any regulator, for any indication, and not the same molecule as any product that has been through a clinical programme. Full-length thymosin β4 has been developed as a drug candidate (RGN-259 eye drops reached Phase 3 for dry eye and neurotrophic keratopathy; recombinant human thymosin β4 has been trialled in myocardial infarction) — none of that development applies to the TB-500 fragment. A Phase 1/2 study of TB-500 for cardiovascular biomarkers in stable ASCVD (NCT07487363) is recruiting and has not reported. Sports-medicine reviews describe TB-500 as part of an unapproved 'gray market' operating outside regulatory oversight; as a non-approved substance it falls under the anti-doping prohibition on substances with no current regulatory approval.
What to know before anything else
Not approved for human use anywhere. No study of the marketed TB-500 fragment in humans has ever been published — not a dosing study, not a safety study, not a pharmacokinetic study.
TB-500 and thymosin β4 are not the same molecule, and this is the most consequential confusion around this compound. Human trial data — including intravenous doses of 42 to 1260 mg — belong to full-length 43-amino-acid thymosin β4. Neither those doses nor those safety findings can be assumed to transfer to the fragment.
Listings are inconsistent about whether a stated milligram figure is per injection or per week, so two sources quoting '2.5 mg' can mean a twofold to fivefold difference in weekly exposure.
Thymosin β4 promotes angiogenesis and cell migration, and its overexpression is associated with advanced disease and worse prognosis in several human cancers (colorectal, hepatocellular, thyroid). What administering it does in a person with an existing or undiagnosed tumour has not been studied.
Gray-market supply is outside regulatory oversight; identity, purity and sterility of material sold as TB-500 are not assured, and the label may not describe which of the two molecules is in the vial.
As a non-approved substance it is prohibited in sport regardless of whether it is named individually on a prohibited list.
TB-500 questions
Is there an established human dose for TB-500?
No. No human study of TB-500 as sold has been published — not a dosing study, not a safety study, not a pharmacokinetic study. The one registered trial of the molecule, NCT07487363, a Phase 1/2 study of cardiovascular biomarkers in stable ASCVD, titles its intervention 'Thymosin Beta 4 17-23 Fragment' and is still recruiting, so it has reported nothing. Evidence for this compound is animal-only.
Are TB-500 and thymosin β4 the same molecule?
They are not, and this is the most consequential confusion around this compound. Thymosin β4 is a 43-amino-acid actin-sequestering protein; TB-500 is a seven-residue fragment of it. A 2026 sports-medicine review (PMID 41966639) lists 'Tβ4 (thymosin beta-4)' and 'TB-500 (thymosin beta-4 fragment)' as two separate compounds. Human trial data belong to the full-length protein, and neither its doses nor its safety findings can be assumed to transfer to the fragment.
Why can't the thymosin β4 trial doses be converted into a TB-500 dose?
Because the routes and the scale do not line up. A randomised placebo-controlled Phase 1 gave four cohorts of ten healthy volunteers single then daily 14-day intravenous doses of 42, 140, 420 or 1260 mg of full-length thymosin β4 (PMID 20536472), which is two to three orders of magnitude above the milligram figures sold for subcutaneous use. A separate first-in-human Phase 1 of recombinant human thymosin β4 dosed 0.05-25 µg/kg intravenously (PMID 34346165) — three orders of magnitude below the first, so the two human programmes do not even agree with each other on scale. The remaining trials are topical: a 0.03% gel in venous stasis ulcers (PMID 20536470) and 0.1% RGN-259 eye drops in severe dry eye (PMID 25826322). An intravenous milligram load does not convert into a subcutaneous dose, and neither does a topical percentage.
How does reconstitution volume change the numbers on a TB-500 vial?
The vial holds a fixed mass of peptide and the water sets the concentration. A 5 mg vial mixed with 2 ml of bacteriostatic water gives 2.5 mg/ml, so 0.1 ml on the barrel is 250 mcg; the same vial mixed with 5 ml gives 1 mg/ml and that same 0.1 ml is now 100 mcg. There is a second trap specific to TB-500: listings are inconsistent about whether a stated milligram figure is per injection or per week, so two sources quoting the same number can differ by two- to fivefold in weekly exposure. Confirm which the source meant before drawing anything up, and enter your own vial size and mixing volume above rather than copying someone else's unit count.
What dosing figures do vendors and clinics actually list for TB-500?
Public vendor and clinic pages describe roughly 2 to 5 mg subcutaneously, twice weekly during a 4-6 week loading phase and then once weekly. This is what sellers and clinics list, not what anyone has measured in a trial. It is not a recommended dose and must not be presented as one. The published human trials of the parent protein used daily intravenous infusion or several-times-daily topical application, so the weekly loading-and-maintenance pattern has no trial basis at all.
How is TB-500 regulated, and what is its anti-doping status?
It is not approved by any regulator, for any indication, and it is not the same molecule as any product that has completed a clinical programme. Full-length thymosin β4 has been developed as a drug candidate — RGN-259 eye drops reached Phase 3 for dry eye and neurotrophic keratopathy, and recombinant human thymosin β4 has been trialled in myocardial infarction — but none of that development applies to the fragment. Sports-medicine reviews describe TB-500 as part of an unapproved 'gray market' operating outside regulatory oversight; as a non-approved substance it falls under the anti-doping prohibition covering substances with no current regulatory approval, regardless of whether it is named individually on a prohibited list.
What safety questions about TB-500 are open?
Thymosin β4 promotes angiogenesis and cell migration, and its overexpression is associated with advanced disease and worse prognosis in several human cancers, including colorectal, hepatocellular and thyroid. What administering it does in a person with an existing or undiagnosed tumour has not been studied, so that risk is unquantified rather than shown to be absent. Supply is also unregulated: identity, purity and sterility of material sold as TB-500 are not assured, and the label may not even describe which of the two molecules is in the vial. There is no manufacturer stability data either, because no approved product exists — vendor guidance to refrigerate sealed vials and use reconstituted material within a few weeks is convention, not tested stability.
The rest of the math
- Reconstitution calculatorThe full version of the tool above, with syringe barrel sizes and IU conversion.
- Vial longevityHow many doses a vial holds and the date it runs out.
- Cost per doseVial price against doses drawn, so two vial sizes can be compared honestly.
- Half-life and decayFirst-order clearance, time to steady state, and what remains at a given hour.
Same class as TB-500
You worked out the draw. Now log this dose.
A calculator answers once and forgets. Dosavy keeps the concentration you mixed, the doses you actually took, and a reminder for the next one — with the same evidence labels you see on this page.