TB-500 (Thymosin Beta-4) reconstitution calculator

Enter your vial amount and target dose. DrawDose returns the BAC water volume, syringe units, and a vial label you can copy.

Two molecular identities sold under one name

The compound sold as "TB-500" in research peptide markets has confusing molecular identity. Two distinct peptides circulate under the same name, with very different molecular weights and dosing implications.

The full-length thymosin beta-4 molecule (Tβ4) is a 43-amino-acid peptide encoded by the TMSB4X gene in humans. Per the published literature on Tβ4 clinical trials (Goldstein et al. 2012; Ruff et al. 2010), this is the molecule that has been studied in human cardiac repair and dermal wound healing trials at doses up to 900 mg intravenously. Molecular weight is approximately 4,963 g/mol per published structural data. Some sources cite Tβ4 as 44 amino acids depending on N-terminal acetylation conventions.

The Ac-LKKTETQ heptapeptide is a 7-amino-acid synthetic fragment corresponding to residues 17-23 of full-length Tβ4. This fragment contains the actin-binding motif and is what some technical literature defines as TB-500 specifically. PubChem CID 62707662 lists this heptapeptide with molecular formula C38H68N10O14 and molecular weight 889 g/mol. This fragment was developed for stability and production efficiency advantages over the full-length peptide.

In practice, the peptide vials sold as TB-500 in the research peptide marketplace are typically the full-length or near-full-length molecule, not the heptapeptide fragment. Vendors describing "TB-500" with molecular weights in the 4,500-5,000 Da range are selling thymosin beta-4 itself; vendors describing molecular weights near 889 Da would be selling the heptapeptide fragment, which is rare in the consumer-facing market.

This page covers the dosing math and protocols documented for the full-length molecule, which is what users typically have in front of them. Verify the molecular weight on the COA before calculating doses. If your vial COA reports 889 Da, you have the heptapeptide fragment and the dosing protocols below do not directly apply.

Quick answer for the most common vial sizes

The 5 mL : 5 mg ratio documented across compounding pharmacy formulation guides for TB-500 produces a 1 mg/mL concentration, where every 100 units delivers 1 mg.

The math holds at any concentration. DrawDose accepts any vial size and any BAC water volume and returns the correct syringe draw for the dose entered.

The 1 mg/mL ratio is the standard for TB-500 because it puts the typical 1 mg per-injection dose at exactly 100 units — easy to draw, easy to verify visually. Higher concentrations work but require smaller, more error-prone draws for the same dose.

How to reconstitute lyophilized TB-500

The procedure follows the standard sterile-injection prep workflow documented in compounding pharmacy formulation guides and peptide stability literature.

Bring the vial and BAC water to room temperature for 15 to 20 minutes before mixing. Cold liquid hitting cold powder slows dissolution and increases the chance of clumping. Wipe both vial tops with an alcohol swab and let them dry. Draw the BAC water into a 1 mL syringe.

Insert the needle into the TB-500 vial at an angle so the water runs down the inside wall, not directly onto the powder pellet. Direct impingement on lyophilized peptide generates foam and can affect peptide structure. Once the water is in, swirl the vial gently for 20 to 30 seconds. Do not shake. TB-500 dissolves clearly when properly reconstituted; cloudiness or particulate that does not clear within a minute indicates a sourcing concern.

Why concentration determines syringe units

The relationship between vial size, BAC water, and syringe draw is fixed by concentration math. A 5 mg vial with 5 mL of water gives 1 mg/mL — every 100 units delivers 1 mg. The same 5 mg vial with 2 mL of water gives 2.5 mg/mL, where 100 units delivers 2.5 mg. To hit a 1 mg target dose with the second mix, the draw is 40 units instead of 100.

Standard reconstitution practice keeps the draw between 10 and 100 units on a 1 mL insulin syringe. TB-500's typical 1-2 mg per-injection dose at 1 mg/mL puts the draw at 100-200 units, which is at or above the standard 1 mL syringe capacity. Splitting weekly doses into two separate injections is the documented workaround across community protocols. DrawDose computes this automatically; the auto-selected BAC water volume on the result panel is tuned to keep the draw in a measurable band.

Documented dosing protocols

There are no FDA-approved TB-500 dosing protocols because TB-500 is not an FDA-approved drug. Per the Vasireddi et al. 2025 systematic review on regenerative peptides, controlled human clinical trial data on TB-500 specifically is limited. Most published trials studied the full-length thymosin beta-4 molecule (often as RGN-137 or RGN-259 trade names) for specific indications including chronic wound healing, dry eye disease, and cardiac repair after myocardial infarction.

Per Goldstein et al. 2012 and Ruff et al. 2010, intravenous Tβ4 has been administered at doses up to 900 mg per dose in clinical trials with acceptable tolerability. These doses are far higher than the subcutaneous community protocols used for athletic recovery and tissue repair, reflecting the difference between the studied medical applications and the off-label use cases.

Community protocol surveys aggregated from r/Peptides, r/PeptideHowTo, and clinician-published peptide guides describe TB-500 dosing as follows.

The standard loading phase runs 4 to 6 weeks at 4 to 10 mg total weekly, typically split into two injections of 2 to 5 mg each. The most common pattern is 4-5 mg twice weekly, totaling 8-10 mg per week. The split-dosing approach reflects both the practical syringe-volume constraints and the long half-life of the molecule.

The maintenance phase runs after the loading period at 2 to 5 mg total weekly, often as a single weekly injection or split into two smaller injections. Maintenance can continue indefinitely or cycle on/off in 8-12 week intervals; community practice varies.

The half-life of full-length Tβ4 is approximately 2 to 3 hours per pharmacokinetic data referenced in the Goldstein et al. review, but the biological effects (actin sequestration, downstream tissue repair signaling) extend well beyond the plasma half-life. This is why infrequent dosing (twice weekly or weekly) is common despite the relatively short plasma residence time.

For specific injuries, community protocols often combine TB-500 with BPC-157 — the canonical pairing documented across athletic recovery contexts. The two compounds target different aspects of tissue repair (TB-500 at the systemic actin-sequestration level, BPC-157 at the local angiogenesis and growth factor level) and are commonly used together for tendon, ligament, and joint injuries.

Adverse reactions and safety profile

Per the Ruff et al. 2010 single and multiple-dose IV trial in healthy volunteers, intravenous thymosin beta-4 at doses up to 1,260 mg total over 14 days was well tolerated. The most common adverse events were headache, injection site reactions, and mild upper respiratory symptoms with incidence comparable to placebo. No serious adverse events attributable to study drug were reported.

Subcutaneous community use of TB-500 has no controlled trial data documenting adverse reactions. Survey data from r/Peptides describes the most common subjective effects as transient lethargy in the first 2 to 5 days of a loading phase, mild injection site reactions, and occasional headache. Long-term safety data does not exist for the subcutaneous protocols used in community practice.

Theoretical safety concerns documented in the broader Tβ4 literature relate to the angiogenic properties of the peptide. Per the cardiovascular and oncology research referenced in the Vasireddi review, Tβ4 promotes vascular endothelial cell migration and capillary formation. Whether this poses a risk in users with active or latent cancer is undetermined; users with current or recent malignancy are universally contraindicated in clinical-practice guidelines for regenerative peptides. No clinical trial has reported tumor-promoting effects in human patients, but the published safety record is bounded by the trial durations (weeks to months, not years).

Pregnancy, untreated thyroid disorders, and known active cancer are documented contraindications in clinical-practice references. Long-term human safety data does not exist beyond the trial durations.

WADA prohibited status

TB-500 has been on the World Anti-Doping Agency Prohibited List since 2011. Per WADA's classification, both TB-500 and full-length thymosin beta-4 fall under category S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics), banned at all times — in and out of competition — for athletes subject to anti-doping testing.

Detection is via specialized mass spectrometry assays. Per published anti-doping literature, the detection window for TB-500 in urine is approximately 2 to 4 weeks after last administration, though detection capabilities have improved since the original 2011 listing. Athletes who have used TB-500 within recent months should expect detection if tested.

Common reconstitution errors

Compounded peptide forums and pharmacy QA literature document a recurring set of errors specific to TB-500.

Confusing the heptapeptide fragment with the full-length molecule. As described above, the literature uses "TB-500" inconsistently. A vial COA reporting 889 Da is the heptapeptide fragment; a vial COA reporting 4,500-5,000 Da is the full-length molecule. Dosing protocols in community practice apply to the full-length molecule. The fragment, if obtained, would be dosed differently and has minimal community protocol data.

Drawing the full weekly dose in a single injection. A 4 mg dose at 1 mg/mL is 400 units, which exceeds 1 mL insulin syringe capacity. Splitting the weekly dose into two 2 mg injections (each 200 units, requiring two syringe draws or a larger 3 mL syringe) is the documented workaround. The cheat sheet's 100 units per injection assumes 1 mg per injection × 2 weekly, totaling 2 mg per week — a more conservative protocol than some community surveys document but one that fits cleanly within standard syringe capacity.

Reusing reconstituted vials beyond 2 to 4 weeks. Per peptide stability literature, reconstituted TB-500 remains stable for approximately 2 to 4 weeks at 2 to 8°C with bacteriostatic water containing benzyl alcohol preservative.

Trusting the vial label over the COA. Compounded and research-grade vials run 5 to 15% off label in industry-published variance data. The COA reports the actual measured peptide content per the lot's HPLC and mass spec assays.

Storage and shelf life

Per peptide stability literature, reconstituted TB-500 stays stable for 2 to 4 weeks at 2 to 8°C (36 to 46°F) when reconstituted with bacteriostatic water. Sterile water without preservative produces a 24-hour shelf life from first puncture.

Lyophilized TB-500 stores for 24 months or longer at -20°C and 12 months or longer at 2 to 8°C, per the same stability literature. Heat exposure during shipping is the most documented threat to potency.

What to verify on a Certificate of Analysis

The COA reports the actual peptide content of a specific lot. For TB-500 specifically, the COA also confirms which molecule the vial contains — the full-length thymosin beta-4 (~4,963 Da) or the heptapeptide fragment (~889 Da). This is the single most important piece of information when buying TB-500, since the two molecules are dosed at very different magnitudes and the marketplace uses the names interchangeably.

Net peptide weight is the measured milligrams of peptide in the vial, separate from any excipients (mannitol, sodium chloride) included for stability. Purity by HPLC reflects the percentage of UV-absorbing material that is the target peptide; 95% is the research-grade minimum the peptide industry has converged on, and 98 to 99% is the standard most reputable vendors publish for TB-500.

Mass spec confirmation matches the expected molecular weight and verifies the peptide's identity. Mass spec is particularly important for TB-500 because the difference between full-length and fragment is detectable by mass alone.

Documented combinations

The most documented combination is TB-500 plus BPC-157, the canonical "healing stack" pairing referenced across athletic recovery contexts. Per the Vasireddi et al. 2025 systematic review on regenerative peptides, both compounds promote tissue repair through different mechanisms — TB-500 at the systemic actin-sequestration and angiogenesis level, BPC-157 at the local growth factor and gastric mucosa repair level. The combination is widely used in community protocols for tendon, ligament, joint, and post-surgical recovery, though no peer-reviewed trial has evaluated the pairing as a co-administered protocol in humans.

Typical co-administration: 250 mcg BPC-157 daily plus 1 mg TB-500 twice weekly during loading phase. Both peptides are commonly drawn into the same syringe and injected together, since both are stable in bacteriostatic water solution at clinical concentrations.

GHK-Cu is occasionally added in skin-focused protocols where dermal repair is the goal; the three-peptide combination of BPC-157, TB-500, and GHK-Cu is documented in community protocols for post-surgical scarring, wound healing, and cosmetic recovery contexts.

FAQ

What's the difference between TB-500 and thymosin beta-4?

In published literature, TB-500 sometimes refers specifically to the heptapeptide fragment Ac-LKKTETQ (residues 17-23 of full-length Tβ4) and sometimes refers to synthetic full-length thymosin beta-4. In the research peptide marketplace, vials sold as "TB-500" are typically the full-length molecule. Verify the molecular weight on the COA: 889 Da is the fragment, 4,500-5,000 Da is the full-length molecule.

Is TB-500 banned by WADA?

Yes. TB-500 has been on the World Anti-Doping Agency Prohibited List since 2011 under category S2. Both the full-length molecule and the heptapeptide fragment are banned at all times — in and out of competition — for athletes subject to anti-doping testing.

How long does TB-500 take to work?

Per community protocol surveys and published preclinical research, subjective improvements in injury recovery typically appear within 2 to 4 weeks of starting a loading-phase protocol. Connective tissue healing (tendons, ligaments) generally requires the full 4 to 6 week loading phase plus several weeks of maintenance dosing before full effect. Acute soft tissue injuries may respond faster than chronic conditions.

Can TB-500 and BPC-157 be drawn into the same syringe?

Yes. Per community protocol surveys and the Vasireddi et al. 2025 systematic review, both peptides are chemically compatible in bacteriostatic water solution at clinical concentrations. Many practitioners reconstitute both peptides separately and draw them into a single syringe just before injection. Some compounding pharmacies offer the combination in a single pre-mixed vial.

What's the difference between the loading phase and maintenance phase?

Per community protocol surveys, the loading phase (4-6 weeks at 4-10 mg weekly) saturates the system and produces the bulk of the tissue repair signaling. The maintenance phase (2-5 mg weekly afterward) maintains the elevated state without continuing to escalate. The loading-then-maintenance pattern is convention rather than evidence-based; no controlled trial has compared the loading approach to flat-dose protocols.

Is TB-500 safe long-term?

Long-term human safety data does not exist. The longest published clinical trial on Tβ4 was 14 days (Ruff et al. 2010). Theoretical concerns from the angiogenesis literature relate to potential effects on tumor growth in users with active or latent cancer; users with current or recent malignancy are contraindicated in clinical-practice guidelines for regenerative peptides. Reasonable practice is cycling on/off rather than continuous indefinite use, with breaks every 8-12 weeks.