Research & Reconstitution Library

TB-500 BAC Water & Reconstitution Guide: Concentration Calculator

TB-500 is commonly used to refer to an N-acetylated seven-amino-acid fragment of thymosin beta-4, with the sequence LKKTETQ. It is important to distinguish this fragment from full-length thymosin beta-4 because much of the human clinical literature concerns full-length thymosin beta-4 formulations, not TB-500 itself.

Research information: This page explains TB-500 identity, research evidence, regulatory information and concentration mathematics. It does not establish a clinical dose, recommend injectable use, or provide a medically validated TB-500 reconstitution protocol.
TB-500 molecular structure
TB-500 molecular structure based on the PubChem record for the N-acetylated LKKTETQ peptide fragment.
Compound
TB-500
Chemical identity
N-acetyl-LKKTETQ
Compound class
Synthetic heptapeptide fragment
Molecular weight
Approximately 889.0 g/mol
Regulatory status
Investigational / not FDA-approved
Human TB-500 evidence
No identified human exposure data
Research vial quantity
No universal standard established
Last reviewed
September 10, 2026

How Much BAC Water for TB-500?

There is no single universal BAC-water volume that can be scientifically presented as the correct amount for TB-500. The volume of liquid changes the resulting mathematical concentration while the total quantity of peptide remains unchanged.

For concentration mathematics, use:

Concentration (mg/mL) = Total TB-500 (mg) ÷ Liquid Volume (mL)

For example, if a mathematical example contains 10 mg of TB-500, then 1 mL corresponds to 10 mg/mL, 2 mL corresponds to 5 mg/mL, 2.5 mL corresponds to 4 mg/mL, 3 mL corresponds to approximately 3.33 mg/mL, and 5 mL corresponds to 2 mg/mL.

These are mathematical concentration examples only. They are not TB-500 dosing or treatment recommendations.

Need a different vial quantity or BAC-water volume?

Use the BacScience Universal BAC Water Calculator to calculate a custom mathematical concentration.

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TB-500 Concentration Examples

Because there is no universal TB-500 vial-size standard that should be assumed for research materials, the quantities below are presented as mathematical examples rather than commercial vial specifications.

TB-500 quantity 1 mL 2 mL 2.5 mL 3 mL 5 mL
5 mg 5 mg/mL 2.5 mg/mL 2 mg/mL 1.67 mg/mL 1 mg/mL
10 mg 10 mg/mL 5 mg/mL 4 mg/mL 3.33 mg/mL 2 mg/mL
20 mg 20 mg/mL 10 mg/mL 8 mg/mL 6.67 mg/mL 4 mg/mL

Mathematical examples only. These quantities are not being represented as standardized commercial TB-500 vial sizes.

TB-500 and Thymosin Beta-4: Why the Distinction Matters

TB-500 is commonly identified as the N-acetylated LKKTETQ fragment corresponding to residues 17–23 of full-length thymosin beta-4. Full-length thymosin beta-4 is a much larger 43-amino-acid peptide/protein.

This distinction is essential when interpreting scientific literature. Human clinical trials involving full-length thymosin beta-4 or RGN-259 should not automatically be treated as human clinical evidence for the TB-500 fragment.

Full-length thymosin beta-4 molecular structure
Full-length thymosin beta-4 structural representation. Included for scientific comparison with the TB-500 fragment.
TB-500 and thymosin beta-4 relationship Educational diagram showing TB-500 as the N-acetylated LKKTETQ fragment corresponding to residues 17 through 23 of full-length thymosin beta-4. TB-500 Research Identity TB-500 is distinct from full-length thymosin beta-4 Full-length thymosin beta-4 43-amino-acid peptide Residues 17–23 Ac-LKKTETQ TB-500 N-acetylated heptapeptide fragment Clinical evidence for full-length Tβ4 ≠ clinical evidence for TB-500
BacScience educational diagram illustrating the distinction between full-length thymosin beta-4 and the TB-500 fragment.

How Much BAC Water Should Be Added to TB-500?

There is no universal scientifically established BAC-water volume for TB-500. A particular liquid volume produces a particular mathematical concentration, but the calculation itself does not establish whether that formulation is validated, sterile, stable, compatible or clinically appropriate.

Therefore, BacScience presents concentration calculations rather than assigning a single "correct" TB-500 reconstitution volume.

How much BAC water for TB-500 5 mg?

As a mathematical example, 5 mg divided by 1 mL equals 5 mg/mL. The same 5 mg divided by 2 mL equals 2.5 mg/mL, while 2.5 mL produces 2 mg/mL and 5 mL produces 1 mg/mL.

How much BAC water for TB-500 10 mg?

As a mathematical example, 10 mg divided by 1 mL equals 10 mg/mL. Two milliliters produces 5 mg/mL, 2.5 mL produces 4 mg/mL, 3 mL produces approximately 3.33 mg/mL and 5 mL produces 2 mg/mL.

How does BAC-water volume change TB-500 concentration?

If the total amount of TB-500 remains constant, increasing the liquid volume decreases the calculated concentration. Decreasing liquid volume increases the calculated concentration.

How do you calculate TB-500 concentration?

Use the following equation:

TB-500 concentration = total peptide quantity (mg) ÷ liquid volume (mL)

What Is TB-500?

TB-500 is the common designation for an N-acetylated seven-amino-acid peptide fragment with the sequence LKKTETQ. PubChem identifies the compound as an N-acetyl-L-leucyl-L-lysyl-L-lysyl-L-threonyl-L-glutamyl- L-threonyl-L-glutamine peptide.

PubChem lists TB-500 as CID 62707662 with molecular formula C38H68N10O14 and molecular weight approximately 889.0 g/mol.

Critical terminology: TB-500 should not automatically be treated as equivalent to full-length thymosin beta-4. The two entities have different molecular sizes and sequences.

How TB-500 Relates to Thymosin Beta-4

Full-length thymosin beta-4 is a naturally occurring 43-amino-acid peptide/protein associated with actin binding, cell migration, angiogenesis and tissue-repair processes.

TB-500 corresponds to a short acetylated fragment of that larger molecule. Preclinical research and regulatory documents discuss the fragment separately from full-length thymosin beta-4.

Because of this structural difference, biological findings involving full-length thymosin beta-4 cannot automatically be assumed to apply to TB-500.

Evidence rule: When a paper studies RGN-259, timbetasin or full-length thymosin beta-4, it should be labelled as thymosin beta-4 evidence rather than silently presented as TB-500 evidence.

What Is TB-500 Being Studied For?

01

Tissue Repair Research

TB-500 and thymosin-related compounds have attracted preclinical interest in tissue-repair and regenerative research.

02

Wound-Healing Research

Full-length thymosin beta-4 has been studied in wound models and topical wound-healing trials.

03

Angiogenesis

Thymosin beta-4 research has investigated endothelial migration, angiogenesis and vascular repair.

04

Corneal Repair

Full-length thymosin beta-4 formulations have been investigated in ophthalmic research involving corneal epithelial defects and dry eye.

05

Dermal Healing

Human studies of full-length thymosin beta-4 have investigated topical formulations for certain wounds.

06

Fragment-Specific Research

The FDA's regulatory review treats TB-500 as a separate N-acetylated fragment and identifies important gaps in human exposure and safety information.

Human Clinical Research

TB-500-specific human evidence is very limited. FDA states that it has not identified human exposure data for drug products containing the thymosin beta-4 fragment identified as TB-500.

It is therefore important not to use human clinical studies of full-length thymosin beta-4 as if they were TB-500 clinical trials.

Full-length thymosin beta-4 research

Full-length thymosin beta-4 has been investigated in human clinical trials. For example, a Phase II randomized trial studied 0.1% RGN-259 ophthalmic solution in subjects with severe dry eye. The trial involved 9 patients and used the ophthalmic formulation six times daily for 28 days.

A later randomized Phase III trial studied 0.1% RGN-259 ophthalmic solution in neurotrophic keratopathy. Complete healing at four weeks occurred in 6 of 10 treated subjects compared with 1 of 8 placebo subjects, although the study was small and the primary statistical evidence was limited.

These are studies of an ophthalmic thymosin beta-4 formulation, not evidence establishing a TB-500 injectable dose.

Full-length thymosin beta-4 intravenous research

A separate randomized study investigated synthetic full-length thymosin beta-4 intravenously in healthy volunteers at escalating doses of 42, 140, 420 and 1260 mg, including single and repeated daily exposure over 14 days.

Again, these doses belong to full-length thymosin beta-4 research and must not be presented as TB-500 dosing.

Doses Studied in Published Research

The following table intentionally distinguishes full-length thymosin beta-4 research from TB-500. None of the listed full-length thymosin beta-4 doses should be interpreted as TB-500 dosing guidance.

Study Population Dose / concentration studied Route Frequency Duration Evidence identity
Phase II dry-eye trial Adults with moderate/severe dry eye 0.1% RGN-259 Ophthalmic Six times daily 28 days Full-length thymosin beta-4 formulation
Phase III neurotrophic keratopathy trial Patients with stages 2–3 neurotrophic keratopathy 0.1% RGN-259 Ophthalmic Trial-specific regimen 4-week treatment period Full-length thymosin beta-4 formulation
IV thymosin beta-4 study Healthy volunteers 42–1260 mg IV Single and repeated daily dosing Up to 14 days Synthetic full-length thymosin beta-4
Venous-ulcer Phase II research Patients with venous stasis ulcers Multiple topical Tβ4 concentrations; 0.03% showed potential in the reported study Topical Study-specific Up to 84 days Full-length thymosin beta-4

These are doses or concentrations reported in research, NOT BacScience dosage recommendations. They should not be converted into a TB-500 protocol.

Preclinical Research

The strongest biological evidence surrounding the thymosin beta-4 family comes from laboratory and animal research. Studies have investigated cell migration, angiogenesis, tissue remodeling, inflammatory signaling and wound repair.

Full-length thymosin beta-4 has demonstrated wound-healing and regenerative activity in multiple preclinical models. These findings have helped motivate clinical investigation of topical thymosin beta-4 formulations.

However, preclinical findings involving full-length thymosin beta-4 cannot automatically be transferred to the much smaller TB-500 fragment.

Evidence boundary: Cell and animal findings are mechanistic or preclinical evidence. They do not establish human efficacy, safety or dosing.

TB-500 Research Reconstitution & Concentration

From a mathematical perspective, concentration is determined by dividing the total peptide quantity by the liquid volume.

Core equation

mg/mL = mg ÷ mL

Example:

10 mg ÷ 2 mL = 5 mg/mL

This describes mathematical concentration only. It does not establish whether the formulation is sterile, stable, compatible or suitable for human use.

Worked examples

  • 5 mg ÷ 1 mL = 5 mg/mL
  • 10 mg ÷ 1 mL = 10 mg/mL
  • 10 mg ÷ 2 mL = 5 mg/mL
  • 10 mg ÷ 2.5 mL = 4 mg/mL
  • 20 mg ÷ 5 mL = 4 mg/mL

BAC Water vs. TB-500 Concentration

BAC-water volume and peptide quantity are separate variables. If the amount of TB-500 remains constant, changing liquid volume changes the calculated concentration.

More liquid

Increasing liquid volume decreases the calculated mg/mL concentration when peptide quantity remains constant.

Less liquid

Decreasing liquid volume increases the calculated mg/mL concentration when peptide quantity remains constant.

Same peptide quantity

Changing liquid volume does not change the original quantity of peptide represented by the starting material.

Concentration is not dose. A calculated mg/mL value does not establish the amount a person should receive, nor does it establish sterility, stability, compatibility or clinical suitability.

Research Limitations & Safety

FDA currently identifies thymosin beta-4 fragment (LKKTETQ), also known as TB-500, among substances for which compounded drugs may present significant safety risks.

FDA states that compounded drugs containing this fragment may pose a risk of immunogenicity for certain routes because of potential aggregation and peptide-related impurities.

Most importantly for this page, FDA states that it has not identified human exposure data for drug products containing the thymosin beta-4 fragment and lacks important information regarding whether the substance could cause harm when administered to humans.

No clinically established human TB-500 dose has been identified.

Human clinical findings involving full-length thymosin beta-4 should not be converted into TB-500 dosing recommendations.

Why formulation science matters

Mathematical concentration is only one part of formulation science. A complete formulation assessment may require consideration of peptide identity, purity, aggregation, degradation, pH, excipients, sterility, container compatibility, storage conditions and route-specific requirements.

FDA's 2026 PCAC material specifically notes that TB-500 free base has formulation- and environmental-condition sensitivity associated with aggregation and degradation. This reinforces why a simple concentration calculation should not be treated as proof of formulation stability.

Frequently Asked Questions About TB-500 BAC Water

How much BAC water should be added to TB-500?

There is no universal scientifically established BAC-water volume for TB-500. A mathematical concentration can be calculated from peptide quantity and liquid volume, but that does not establish a clinical formulation or dosing protocol.

What is the TB-500 reconstitution formula?

For concentration mathematics, divide the total TB-500 quantity in milligrams by the liquid volume in milliliters to obtain mg/mL.

What concentration is 10 mg of TB-500 in 2 mL?

Mathematically, 10 mg ÷ 2 mL = 5 mg/mL. This is a concentration calculation and not a dosing recommendation.

What concentration is 10 mg of TB-500 in 2.5 mL?

Mathematically, 10 mg ÷ 2.5 mL = 4 mg/mL.

Does adding more BAC water lower TB-500 concentration?

Yes. If the total TB-500 quantity remains constant, increasing liquid volume lowers the calculated concentration.

Is TB-500 the same as thymosin beta-4?

No. TB-500 generally refers to an N-acetylated seven-amino-acid fragment, LKKTETQ, while full-length thymosin beta-4 is a 43-amino-acid peptide.

Has TB-500 been studied in humans?

FDA states that it has not identified human exposure data for drug products containing the TB-500 thymosin beta-4 fragment. Human studies of full-length thymosin beta-4 exist, but they should not be represented as TB-500 studies.

Has thymosin beta-4 been studied in humans?

Yes. Full-length thymosin beta-4 formulations have been investigated in clinical studies including ophthalmic, topical wound and intravenous research.

Is TB-500 FDA approved?

TB-500 is not an FDA-approved therapeutic drug.

Is there a clinically established human TB-500 dose?

No clinically established human TB-500 dose has been identified.

Are thymosin beta-4 research doses the same as TB-500 doses?

No. Full-length thymosin beta-4 and TB-500 are chemically distinct. A dose or concentration studied for full-length thymosin beta-4 cannot automatically be transferred to TB-500.

Can the BacScience calculator calculate TB-500 concentration?

Yes. The Universal BAC Water Calculator can calculate mathematical concentration from a custom peptide quantity and liquid volume.

Open the BAC Water Calculator →

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Scientific References

  1. PubChem — TB-500 / CID 62707662
    Chemical identity, sequence, molecular formula and molecular weight for the N-acetylated LKKTETQ peptide.
  2. FDA — Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks
    FDA regulatory information concerning thymosin beta-4 fragment (LKKTETQ), also known as TB-500.
  3. FDA Pharmacy Compounding Advisory Committee — July 23–24, 2026
    Regulatory materials concerning TB-500 free base and TB-500 acetate in the context of wound-healing use.
  4. Sosne G et al. — Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial.
    Cornea. 2015. PMID: 25826322.
  5. Sosne G et al. — 0.1% RGN-259 Ophthalmic Solution in Neurotrophic Keratopathy.
    Phase III randomized placebo-controlled trial. PMID: 36613994.
  6. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta-4 in healthy volunteers.
    PMID: 20536472.
  7. The effect of thymosin treatment of venous ulcers.
    Phase II topical full-length thymosin beta-4 research. PMID: 20536470.
  8. Treatment of chronic nonhealing neurotrophic corneal epithelial defects with thymosin beta4.
    Topical full-length thymosin beta-4 clinical experience. PMID: 20536469.
Last scientifically reviewed: September 10, 2026
Scientific reviewer: BacScience Research Editorial Team
Review standard: Primary-source-first review using FDA, PubMed, PubChem and regulatory research sources.

Calculate Your TB-500 Research Concentration

Enter a peptide quantity and liquid volume into the BacScience Universal BAC Water Calculator to calculate the resulting mathematical concentration.

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