# TB-500 Dosage in the Research Literature: Routes, mg/kg, and Half-Life > TB-500 dosage as it appears in the research literature: animal mg/kg ranges, the human Phase 1 IV doses of full-length thymosin beta-4, routes studied, and the half-life gap. What was administered, to which species, by which route, at which figure. Plus the half-life line, which for the fragment reads NONE-VALIDATED. ## TB-500 Dosage in the Research Literature TB-500 dosage figures in the literature describe what was given to animals or to volunteers in a controlled study — not a human regimen, and not a recommendation. Animal efficacy work dosed full-length thymosin beta-4 across a wide range. In the rat embolic-stroke dose-response study, intraperitoneal thymosin beta-4 was given at 2, 12 and 18 mg/kg, with a modeled optimal near 3.75 mg/kg; benefit appeared at 2 and 12 mg/kg but not at 18 mg/kg [4]. Cardiac and neurological rodent models have used figures in the single-digit-to-low-double-digit mg/kg range [2][4]. In a muscular-dystrophy (mdx) mouse study, the protein was dosed at 150 micrograms twice weekly intraperitoneally for six months — a research schedule, with that study finding more regenerating fibers but no gain in strength. Human dosing exists only for full-length thymosin beta-4 and only in a safety setting: a Phase 1 study gave synthetic thymosin beta-4 intravenously at 42, 140, 420 and 1260 mg — a single dose, then daily for 14 days — and found it well tolerated to the top dose [6]. In vitro, the protein is bioactive at picogram-to-nanogram amounts; roughly 10 pg stimulated keratinocyte migration [3]. None of these are TB-500-heptapeptide human doses, and none translate to an administration instruction. ## Half-Life and Pharmacokinetics in the Literature No validated human pharmacokinetic half-life exists for the TB-500 heptapeptide. The closest human pharmacokinetic data are from the intravenous full-length thymosin beta-4 Phase 1 study, where pharmacokinetics were dose-proportional and half-life increased with dose [6]. Anti-doping LC-MS work characterizes TB-500 and its metabolites in equine plasma and urine for detection purposes — not for human pharmacokinetic modeling. As a short acetylated peptide, TB-500 is more chemically robust than the full-length protein but is still subject to proteolysis and freeze-thaw degradation. It is supplied as a lyophilized powder for research use, reconstituted in bacteriostatic or sterile water and kept refrigerated. The TB-500 half-life question, read honestly, returns no human number for the fragment. ## Routes studied and what they are not The routes that appear in the literature are intraperitoneal (predominant in rodent efficacy studies), intravenous (the human Phase 1 of full-length thymosin beta-4 and some cardiac models), and topical or ophthalmic (corneal and dermal wound and dry-eye trials of full-length thymosin beta-4 / RGN-259) [3][6][11]. Subcutaneous and intramuscular routes circulate in research-use community contexts but are not drawn from controlled human efficacy trials. One caution sits over all of it. Non-clinical loading-then-maintenance protocols circulated in athletic and peptide-research communities are not derived from controlled human trials and have no published clinical validation. The non-monotonic stroke result — where 18 mg/kg underperformed 2 and 12 mg/kg [4] — directly undercuts the more-is-better logic those protocols assume. The dosage record is a research record, and this page reports it as one. Route also shapes the safety question that governs the compound's standing. FDA's concern for this fragment centers on potential immunogenicity for certain routes of administration and a lack of important safety information [16] — a regulatory reading of exactly the parenteral routes (intraperitoneal, intravenous, subcutaneous, intramuscular) that the research and community contexts use. The routes are documented; what is absent is a controlled human safety dataset for the heptapeptide by any of them [13]. ## Why a research dose is not a dose The reason this page reports figures without translating them is that the numbers do not transfer. The mg/kg values come from full-length thymosin beta-4 in rodents [2][4]; the milligram values come from intravenous dosing of the protein in a 40-person Phase 1 safety study [6]; the picogram activity comes from cell-culture migration assays [3]. Three different molecules-in-context — protein versus fragment, rat versus human, in vivo versus in vitro — sit behind those numbers, and none of them maps onto a person taking the heptapeptide. The stability picture sharpens the point. TB-500 is supplied as a lyophilized powder for research use, reconstituted in bacteriostatic or sterile water and refrigerated; as a short acetylated peptide it is more robust than the full-length protein but still degrades through proteolysis and freeze-thaw. Identity and purity of research-grade material are a recurring concern, because an unverified sequence or an impure preparation makes any reported figure meaningless [13]. A dose is only a dose when the molecule, the route, the recipient and the material are all pinned down — and for the TB-500 fragment in humans, they are not. This is the [TB-500 dosage in the research literature](/dosage), reported as a research record and nothing more. --- Legit TB-500 runs the thymosin beta-4 literature like a status check: the seven-mer marked present, the full-length protein where the data actually live marked separately, the human-evidence column returning zero, and FDA's standing quoted straight — a console for verifying claims, not a clinic, a pharmacy, or a place anything is sold.