TB-500: Reference Overview and Reconstitution Notes

TB-500

What it is

TB-500 is a synthetic, N-acetylated heptapeptide (sequence Ac-LKKTETQ) that corresponds to the amino acid 17 to 23 region of thymosin beta-4, a naturally occurring actin-binding protein. It is a short peptide fragment, not the full 43 amino acid thymosin beta-4 molecule, though the two names are often used interchangeably in marketing.

Research context and categorization

TB-500 is generally grouped under the healing and tissue-repair category of research peptides. The fragment corresponds to the actin-binding region of thymosin beta-4, and in that context it is studied in relation to actin regulation and cell migration. Because of this proposed mechanism, it is commonly discussed in relation to wound healing, angiogenesis, and general tissue repair in preclinical and animal models.

These uses are investigational. Much of the peer-reviewed literature that specifically names TB-500 is oriented toward detecting it as a doping agent in human and equine sport, rather than confirming therapeutic outcomes. Human clinical data on the TB-500 fragment itself are limited, and products sold under the TB-500 name are not always chemically identical to the full-length recombinant thymosin beta-4 used in clinical studies. None of the tissue-repair or healing effects described in preclinical work should be read as confirmed or approved benefits.

Status

  • Regulatory status: Research-only. TB-500 is not FDA-approved for human or veterinary use, and no pharmaceutical sponsor has an approved indication for it. It is handled as a research chemical for laboratory use.
  • Sport status: Prohibited under the WADA Prohibited List. Thymosin beta-4 and its derivatives, including TB-500, are named as examples under the growth factors and growth factor modulators class, prohibited at all times, both in and out of competition.

Reconstitution notes (general)

TB-500 is typically supplied as a lyophilized (freeze-dried) powder that is reconstituted with bacteriostatic water before use in the lab. The working concentration follows a simple relationship: concentration equals the milligrams of peptide in the vial divided by the millilitres of bacteriostatic water added. For example, 5 mg of powder in 2 mL of water gives 2.5 mg/mL. To work out concentration and volumes for a given vial, use the calculator at /pages/tools.

Dilution and handling notes (compound-specific)

TB-500 is most often sold in 5 mg or 10 mg vials. Common reconstitution volumes produce concentrations in roughly the 1 to 5 mg/mL range: for a 5 mg vial, 1 mL of bacteriostatic water yields about 5 mg/mL, 2 mL yields about 2.5 mg/mL, and 5 mL yields about 1 mg/mL. The volume chosen is a matter of how concentrated the working solution needs to be, not a fixed requirement.

As a short, highly water-soluble heptapeptide, TB-500 generally goes into solution readily and does not have the gelling or cloudiness problems seen with some larger or more hydrophobic peptides. Standard handling still applies: add the water slowly, aiming the stream against the inner glass wall rather than directly onto the powder, then let the vial sit and swirl gently to dissolve. Do not shake vigorously, since mechanical agitation and foaming can stress peptide chains. A properly reconstituted solution should be clear and colorless.

Handling and storage

Keep reconstituted TB-500 refrigerated at 2 to 8 C and out of direct light. Wipe the vial stopper with an alcohol swab before each access, and label the vial with the mix date so age can be tracked. Reconstituted solution is generally considered usable for about four weeks under refrigeration. Discard the solution if it becomes cloudy or discolored, or if visible particles or floaters appear. Unopened lyophilized powder is more stable and should also be stored cold, out of light.

Related reading

Tools and supplies

For laboratory and research reference only. Educational content, not medical, dosing, injection, or therapeutic guidance, and not intended for human or animal use. Any research uses described are investigational and not confirmed or approved benefits. Confirm anything involving health with a licensed professional. References linked above.