FreePeptideCalc

TB-500 Dosage Calculator

A name that covers two different molecules. Real human trials exist for one of them — none used the injectable musculoskeletal route TB-500 is actually sold for.

Written by , who builds and maintains this site and is not a clinician. Every figure links to its primary source.

Not approved

Not approved, and not lawfully compoundable

Added to the FDA's 503A Category 2 list on 29 September 2023 as “Thymosin beta-4 fragment (TB-500)”, then removed on 22 April 2026 when the nominations were withdrawn — without being moved to Category 1. On the FDA's Category 2 page it now appears only under “nominated but withdrawn”, and it is absent from all three categories of the nominated-substances list, which leaves it outside the statutory conditions for compounding. The Pharmacy Compounding Advisory Committee voted 8–6 on 23 July 2026 to recommend it for wound healing; that recommendation is advisory and no rulemaking has followed.

No approved human dose exists for this compound in any country. The figures below are the doses used in named published studies, reproduced for reference only. Doses given to rats or mice do not convert to a human dose. The FDA has stated that labelling a product “research use only” or “not for human consumption” does not change its legal status when the seller's own marketing shows it is intended for people.

Anti-doping: Prohibited at all times. WADA class S2 (peptide hormones, growth factors and mimetics). USADA notes that topical use of a growth factor is just as prohibited as injectable. Anti-doping laboratories have published a method for detecting the TB-500 fragment specifically in plasma and urine.

Calculator inputs

Set up your vial

Enter the label, dilution and dose. The result updates as you type.

Syringe volume
Syringe volume
TB-500 in the vial
TB-500 in the vial
Vials sold online are commonly 2–10 mg
Bacteriostatic water to add
Bacteriostatic water to add
mL
Dose per injection
Dose per injection
No approved human dose exists for this compound. The dose shown is only a calculator input, not a recommendation or starting point.
More optionsReverse calculation, schedule and cost

Enter the bacteriostatic water you added and get the volume to draw.

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25units(0.25 mL)
25 units01020304050Drag the plunger, or focus it and use the arrow keys
Draw to 25 units on a 50-unit U-100 syringe.
Concentration
2000 mcg/mL
Water added
2.5 mL
Doses in vial
10
How the concentration is calculated

This divides the peptide by the water you add. The powder occupies a little volume of its own, which is negligible on a typical vial but not on one with a heavy bulking agent. When a product label states a concentration, use the label’s number.

Key facts

Molecular weight
4,963 DaThat figure is full-length thymosin beta-4, 43 amino acids. “TB-500” properly names something else: the N-terminal acetylated 17–23 fragment, Ac-LKKTETQ, which PubChem carries as its own compound at 889 Da. When a doping-control laboratory analysed an actual product sold as TB-500, that 889 Da fragment is what it found — not the 4963 Da protein. Vendors also sell the full-length peptide under the same name, and nothing on a label reliably tells you which is in the vial. The two differ 5.6-fold in mass, so any calculation done in moles rather than milligrams is wrong by that factor if you guess.
Half-life
Not published. No accessible human pharmacokinetic study reports one, so any specific figure quoted elsewhere has no primary source behind it.
Also sold as
Thymosin Beta-4, Tβ4, TB4, Ac-LKKTETQ

Doses used in published studies

These are reproduced for reference. They are not recommendations, and an animal dose in mg/kg does not convert to a human dose.

humanintravenous — single dose, then once daily for 14 days

42 mg, 140 mg, 420 mg and 1260 mg

Four cohorts of ten healthy volunteers given synthetic full-length thymosin beta-4, published in 2010. Adverse events were infrequent and mild to moderate, with no dose-limiting toxicity. Every one of these doses exceeds the entire contents of a vial sold as TB-500, and all of them went in intravenously under clinical supervision.

humanintravenous — single ascending dose, and once daily for 10 days

0.05 to 25 µg/kg single dose; 0.5, 2 or 5 µg/kg daily

Phase 1a (54 volunteers) and phase 1b (30 volunteers) of recombinant human thymosin beta-4, NL005. These doses sit roughly a thousandfold below the 2010 programme above, for the same molecule by the same route. Nobody has reconciled the two, which is the clearest evidence there is that no settled systemic dose exists.

humanintravenous, once daily for 7 days after coronary intervention

0.5 µg/kg, and a high-dose arm registered inconsistently as 1.0 or 1.5 µg/kg

A phase 2 trial in 90 patients with acute myocardial infarction, starting 12 hours after percutaneous coronary intervention. The registry record contradicts itself: its arm description says 1.0 µg/kg and its intervention description says 1.5 µg/kg for the same arm, so the high dose is not reliably stated anywhere.

humanophthalmic (eye drops), five times a day

0.1% thymosin beta-4 solution

SEER-1, a phase 3 trial of RGN-259 in 18 patients with stage 2 or 3 neurotrophic keratopathy. Complete healing at day 29 was 6 of 10 on drug against 1 of 8 on placebo, narrowly missing significance (p = 0.0656); the difference reached significance two weeks after treatment stopped (p = 0.0359). A 0.05% strength was used in the dry eye programme.

humantopical gel, once daily for up to 84 days

0.01%, 0.03% and 0.1% w/w

A phase 2 trial in 72 patients with venous stasis ulcers. The same three strengths were used in the epidermolysis bullosa and pressure ulcer trials. A percentage strength applied to a wound is not convertible into a milligram injection.

ratintraperitoneal, once daily for 4 weeks

60 µg/kg per day

A 2026 Achilles tendon transection-and-repair model in 32 Sprague-Dawley rats of about 330 g. The TB-500 group reached a significantly higher maximum load to failure than controls and had the best histology scores in the study. This is a rat figure and does not convert to a human dose.

How good is the evidence?

Genuine human trials exist, and none of them is the product being sold. Full-length thymosin beta-4 has been through an intravenous phase 1 in healthy volunteers, phase 2 and phase 3 eye drops, phase 2 topical gels for venous stasis ulcers, pressure ulcers and epidermolysis bullosa, and phase 2 intravenous dosing after a myocardial infarction. There is no human trial of the acetylated 17–23 fragment a laboratory actually found inside TB-500, and no human trial of subcutaneous thymosin beta-4 for tendon, ligament or muscle injury — the use it is marketed for. Two independent intravenous programmes chose doses roughly a thousandfold apart, which is a fair measure of how unsettled the systemic dose still is.

Common questions

Sources

Every number on this page comes from one of the documents below. Where no reliable source exists, the page says so instead of filling the gap.

  1. RegulatorFDA· 2026-05-14
    Bulk Drug Substances Nominated for Use in Compounding Under Section 503A
  2. RegulatorFDA
    Certain Bulk Drug Substances for Use in Compounding May Present Significant Safety Risks
  3. RegulatorFDA· 2026-07
    July 23–24, 2026 Meeting of the Pharmacy Compounding Advisory Committee
  4. RegulatorWorld Anti-Doping Agency· 2026
    WADA 2026 Prohibited List
  5. RegulatorUSADA
    Peptides, Growth Hormones and Cosmetics
  6. Published studyPubMed Central
    Thymosin beta-4 (RGN-259) phase 3 in neurotrophic keratopathy
  7. Published studyAnnals of the New York Academy of Sciences 2010;1194:223–9· 2010-04
    Ruff D, Crockford D, Girardi G, Zhang Y. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta 4 in healthy volunteers
  8. Published studyDrug Testing and Analysis 2012;4(9):733–8· 2012-09
    Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500
  9. Published studyJoint Diseases and Related Surgery 2026;37(3):822–37· 2026-07
    Biçer O, Adanir O, Güleryüz Y, et al. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: a histopathological and biomechanical study
  10. Published studyAmerican Journal of Sports Medicine 2026;54(1):223–9· 2026-01
    Mayfield CK, Bolia IK, Feingold CL, et al. Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians
  11. Published studySports Medicine 2026;56(8):1921–35· 2026-08
    Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance
  12. ReferenceClinicalTrials.gov· 2017-07
    NCT04555824 and NCT04555850 — phase 1a and 1b intravenous recombinant human thymosin beta 4 (NL005) in healthy volunteers
  13. ReferenceClinicalTrials.gov· 2022-07
    NCT05984134 — phase 2 intravenous recombinant human thymosin beta 4 (NL005) after percutaneous coronary intervention for acute myocardial infarction
  14. ReferenceClinicalTrials.gov· 2006-07
    NCT00832091 — phase 2 topical thymosin beta 4 gel in venous stasis ulcers
  15. ReferenceNIH / National Center for Biotechnology Information
    PubChem compound records (molecular weights and formulae)