TB-500 dosage in the research literature, read as what was given to which species.

TB-500 Dosage in the Research Literature

TB-500 dosage in the research literature is a record of what was administered to animals and in vitro — not a human instruction. Animal studies dose full-length thymosin beta-4 across a wide range: roughly 6-12 mg/kg in cardiac and neuro rodent models, 2-18 mg/kg intraperitoneally in the embolic-stroke dose-response study (with a modeled optimal dose near 3.75 mg/kg) ^[4], and 150 ug twice weekly intraperitoneally for 6 months in the mdx muscular-dystrophy study ^[5]. Picogram-to-nanogram amounts are bioactive in vitro — about 10 pg was active in keratinocyte migration assays, and nanomolar thymosin beta-4 stimulates hair-follicle stem cells ^[3][5].

The single human dosing dataset is intravenous and used the protein, not the fragment: a Phase 1 study dosed synthetic thymosin beta-4 at 42, 140, 420 and 1260 mg as a single dose then daily for 14 days ^[6]. Two cautions belong on every dose number here. First, the routes studied differ from the routes used in research-peptide communities — intraperitoneal predominates in rodent efficacy work, intravenous in the human Phase 1, and topical/ophthalmic in corneal and dermal trials ^[12]. Second, the non-clinical loading-then-maintenance protocols that circulate in athletic and peptide-research communities are not derived from controlled human trials and have no published clinical validation ^[12].

Why 'higher' is not 'better': the non-monotonic signal

The stroke dose-response study is the clearest argument against scaling doses up. In male Wistar rats with embolic middle cerebral artery occlusion, intraperitoneal thymosin beta-4 at 2 and 12 mg/kg improved neurological function — significant from day 14 through day 56 — but 18 mg/kg gave no significant benefit, and the authors modeled an optimal dose near 3.75 mg/kg ^[4]. That is a non-monotonic, inverted-U response: the highest dose was not the best dose.

That single result undercuts the rationale behind community loading schemes, which assume more peptide yields more effect ^[12]. It also reinforces why the doses on this page are reported strictly as studied at X mg/kg in [species] and never recast as a human regimen. The dose that helped a rat brain at 12 mg/kg is not a human dose, and 18 mg/kg helped nothing ^[4].

Half-life, routes studied, and material quality

No validated human pharmacokinetic half-life exists for the TB-500 heptapeptide. The only relevant human PK comes from the intravenous full-length thymosin beta-4 Phase 1 study, where half-life increased with dose — dose-proportional pharmacokinetics across the 42-1260 mg cohorts ^[6]. Anti-doping LC-MS work characterizes TB-500 and its metabolites in equine plasma and urine for detection, not for human PK ^[12]. So the half-life question, honestly answered, is not characterized for the fragment in humans.

The routes studied are intraperitoneal (predominant in rodent efficacy studies), intravenous (the human Phase 1 of the protein and some cardiac models), topical and ophthalmic (corneal and dermal wound and dry-eye trials of the full-length protein), and subcutaneous or intramuscular as community research-use routes that do not come from controlled human efficacy trials ^[12]. One practical caveat sits over all of it: research-grade material quality is a recurring concern — peptide identity, purity, and whether the supplied material is the fragment or the full-length protein are not guaranteed in unregulated supply, which complicates interpreting any result ^[12].

What is the half-life of TB-500?

No validated human half-life exists for the TB-500 heptapeptide ^[12]. In the intravenous full-length thymosin beta-4 Phase 1 study, half-life increased with dose (dose-proportional PK) across 42-1260 mg ^[6]. Anti-doping work characterizes the fragment's metabolites in equine matrices for detection, not human pharmacokinetics ^[12].