DOSE LEDGER · RESEARCH CONTEXT ONLY
TB-500 Dosage as the Studies Recorded It
The doses below are what researchers administered to animals and, for the parent protein, to Phase 1 volunteers — read as study parameters, never as human guidance.
TB-500 Dosage in the Research Literature
TB-500 dosage figures in the published record are study parameters, not protocols — and most belong to full-length thymosin beta-4, not the 7-mer. Animal studies dose Tβ4 across a wide range: roughly 6–12 mg/kg in cardiac and neurological rodent models, and 2, 12 and 18 mg/kg intraperitoneally in the rat embolic-stroke dose-response study, where the modeled optimum landed near 3.75 mg/kg [8]. The mdx muscular-dystrophy study used 150 µg twice weekly intraperitoneally for six months.
Picogram-to-nanogram amounts are bioactive in vitro — about 10 pg was active in keratinocyte migration assays, and nanomolar Tβ4 stimulated hair-follicle stem cells [7][5]. These are mechanistic potencies, not dosing instructions.
The most important dosing lesson is the non-monotonic curve: in the stroke study, 2 and 12 mg/kg improved outcomes but 18 mg/kg did not [8]. Higher was not better, which directly undercuts community "loading" rationales.
Human dosing on record: the Phase 1 ladder
The only human dosing data are for synthetic full-length Tβ4. A randomized, placebo-controlled Phase 1 study administered it intravenously at 42, 140, 420 and 1260 mg — a single dose, then daily for 14 days — to 40 healthy volunteers across four cohorts of ten [10]. It was well tolerated to the top dose, with no dose-limiting toxicities and dose-proportional pharmacokinetics in which half-life increased with dose [10].
This is a labeled study ladder for the parent protein, reported here as what the trial administered. It is not a human protocol for the TB-500 fragment, for which no completed human trial exists [10]. Non-clinical "loading then maintenance" schedules circulated in athletic and peptide-research communities are not derived from controlled human trials and have no published clinical validation.
Routes studied
The routes in the literature are specific to the molecules and models tested. Intraperitoneal injection predominates in rodent efficacy studies [8]. Intravenous administration was used in the human Phase 1 of full-length Tβ4 and in some cardiac models [10]. Topical and ophthalmic routes appear in corneal and dermal wound work and the dry-eye trials of full-length Tβ4 / RGN-259 [7][10]. Subcutaneous and intramuscular routes appear in community research use but not in controlled human efficacy trials.
As a short acetylated peptide, TB-500 is supplied lyophilized for research use and reconstituted in bacteriostatic or sterile water with refrigeration. It is more chemically robust than the full-length protein but still subject to proteolysis and freeze-thaw degradation. Identity and purity of research-grade material — including whether a vial contains the fragment or the full-length protein — is a recurring concern.
TB-500 Half-Life: What Is and Is Not Known
No validated human pharmacokinetic half-life exists for the TB-500 heptapeptide [10]. That is a flagged gap, not an oversight: the only human PK on record is for full-length Tβ4, where the Phase 1 study reported dose-proportional kinetics with half-life increasing as dose increased [10]. Anti-doping LC-MS work has characterized TB-500 and its metabolites in equine plasma and urine — but for detection, not for human pharmacokinetic modeling [1]. Any single TB-500 half-life figure presented as a human number is unsupported by the literature.