TB-500 Dosage Chart.

Fifty units, if you mixed a 10 mg vial with 2 mL of bacteriostatic water. That gives 5 mg/mL, and one unit on a U-100 syringe is 0.01 mL, so one unit equals 0.05 mg (50 mcg). On that same mix, 2 mg is 40 units and 5 mg is 100 units. Change the vial size or the water volume and every one of those numbers changes: a 5 mg vial in the same 2 mL makes each unit 0.025 mg, so 2.5 mg becomes 100 units, not 50. Always recalculate from the vial in front of you.

No, and this is the most consequential misunderstanding about the compound. Analytical work published in Drug Testing and Analysis identified the active substance in TB-500 as Ac-LKKTETQ: the N-terminally acetylated 17–23 fragment of thymosin beta-4, seven amino acids, about 889 Da. Full-length thymosin beta-4 is 43 amino acids, about 4,963 Da. Sellers use the two names interchangeably. The molecules are not interchangeable, and the clinical literature belongs to the larger one.

For TB-500 itself in humans, nobody has measured it; there is no published human pharmacokinetic study of the fragment. The closest real number is for full-length thymosin beta-4 given intravenously in the 2021 first-in-human Phase 1, where terminal half-life ran from 0.5 to about 2.08 hours and rose with dose. In rats given TB-500, the parent is degraded quickly: Ac-LK dominates in the first six hours, while Ac-LKK is still detectable at 72 hours. Any confident half-life figure on a product page is not sourced from human data on this molecule.

Because three separate worlds keep getting blended together. The 2010 Phase 1 gave 42 to 1,260 mg of full-length protein intravenously. The modern development programme, including the Phase 2b in acute myocardial infarction, gives 0.5 to 1.0 micrograms per kilogram intravenously, well under 100 mcg for an adult. Research-peptide users inject 2 to 5 mg of a smaller, different fragment subcutaneously. Comparing any two of those directly is meaningless, and a chart that cites a trial number to justify a vial number is doing exactly that.

Clinical reviews describe TB-500 as usually injected subcutaneously or intramuscularly, with limited oral bioavailability. Subcutaneous into the abdomen with rotated sites is the lower-risk default. The popular idea of injecting close to the injured tendon has no human evidence behind it and the proposed mechanism is systemic anyway (actin binding and angiogenesis, not a local depot effect), so deliberately injecting into or beside an inflamed joint or tendon adds real infection risk for a theoretical benefit.

Whatever volume gives you a comfortable draw. The water changes the concentration only, never the dose. A 10 mg vial in 2 mL gives 5 mg/mL, so 2.5 mg is 50 units on a U-100 syringe. The same vial in 1 mL gives 10 mg/mL and that same 2.5 mg becomes 25 units, where a one-unit misread costs you twice as much peptide. Aim for doses that land between roughly 20 and 60 units, add the water slowly down the vial wall, and swirl rather than shake.

No stability study for reconstituted TB-500 has been published, so the common 3–4 week refrigerated window is convention rather than data. What is documented is the diluent: bacteriostatic water contains 0.9% benzyl alcohol as a preservative, which is what makes repeated entry into the vial reasonable at all. Reconstitute with plain sterile water instead and there is no preservative, so the vial should be treated as single-use. Keep it at 2–8 °C, out of light, and discard it if the solution turns cloudy or shows particles.

In sport, assume yes. Thymosin beta-4 is classified by WADA as a prohibited growth factor, and a validated method for detecting Ac-LKKTETQ in plasma and urine was published in 2012, with equine doping-control assays reaching 0.02 ng/mL in plasma and 0.01 ng/mL in urine. It will not appear on a standard workplace or clinical drug screen, which tests for something entirely different. If you are tested in competition, there is no safe protocol here at any dose.

There is no published human study of either compound alone for musculoskeletal repair, and none at all of the two together. No interaction data, no combined safety data, nothing. Beyond the unknown risk, stacking destroys your ability to learn anything: if something improves, you will not know which vial to credit or repeat. Run one at a time, against a measurement you took beforehand.