# TB-500 Dosage in the Research Literature

> TB-500 dosage in preclinical research ranges from 1 µg local delivery in rodent ligament models to 30 mg/kg in rat TBI studies. This page reviews research-context dosing data — not human dosing recommendations.

The TB-500 dosage data that exists in the peer-reviewed literature is preclinical — rodent intraperitoneal injection studies, equine intramuscular administration, local delivery in fibrin sealant, and one Phase I IV study of the full-length Tβ4 protein (not the TB-500 fragment) in humans [16]. No validated human dose-response study for injectable TB-500 has been published.

## TB-500 Loading Phase Protocols in Research

Equine literature references protocols of 2–5 mg given subcutaneously or intramuscularly, 1–2 times per week, over 4–6 weeks — giving rise to WADA's doping-control methodology [18]. These are equine protocols, not validated human doses.

## Preclinical Dose Data by Study

| Dose | Route | Model | Ref |
|---|---|---|---|
| 5.37 mg/kg | IP | Rat cardiac infarction — 43% infarct reduction at 28 days | [6] |
| 6 or 30 mg/kg | IP | Rat TBI — 30 mg/kg superior for sensorimotor recovery | [7] |
| 2–18 mg/kg (optimal 3.75) | IP | Rat embolic stroke — day-56 neurological recovery | [8] |
| 1 µg local | Fibrin sealant | Rat MCL — superior biomechanics at 4 weeks | [9] |
| 150 µg ×2/week, 6 months | IP | Dystrophin-deficient mice — more regenerating fibers, no functional improvement | [11] |
| 12 mg/kg/day, 4 weeks | IP | NAFLD mice — M1→M2 macrophage polarization | [22] |
| 0.05–25 µg/kg (single IV) | IV | Human — full Tβ4 protein (NL005), no serious adverse events | [16] |

## TB-500 Half-Life and Elimination

No validated half-life data exists for injectable TB-500 fragment in humans.

**Full Tβ4 protein (IV, human):** Half-life 0.5–2.08 hours, Tmax 3–15 minutes [16]. Applies to the full 43-amino-acid protein, not the heptapeptide fragment.

**TB-500 fragment (rat):** Primary metabolite Ac-LK peaked at 0–6 hours post-injection; secondary metabolite Ac-LKK detectable up to 72 hours. Metabolite Ac-LKKTE showed significant wound-healing activity. No cytotoxicity for parent or metabolites [19].

## Administration Route

Most preclinical studies used intraperitoneal injection — not clinically relevant for humans. Subcutaneous and intramuscular routes are referenced in equine contexts without head-to-head comparison [18]. No human pharmacokinetic route comparison exists.

## Research-Grade Purity

Internet-marketed TB500/TB1000 products are "not systematically consistent with their descriptions" [17]. Bacterial endotoxin contamination, incorrect sequences, undisclosed excipients, and heavy metals represent independent safety hazards.

## References

[3] Malinda KM, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999.
[6] Bao W, et al. Cardioprotection by systemic dosing of thymosin beta four. Front Pharmacol. 2013.
[7] Xiong Y, et al. Neuroprotective effects of thymosin beta4 in TBI rats. J Neurosurg. 2012.
[8] Morris DC, et al. Dose-response study of thymosin β4 for acute stroke. J Neurol Sci. 2014.
[9] Xu B, et al. Thymosin β4 enhances MCL healing in rat. Regul Pept. 2013.
[11] Spurney CF, et al. Chronic Thymosin β-4 in the dystrophin-deficient mouse. PLoS One. 2010.
[16] Wang X, et al. Phase I study of recombinant human thymosin β4. J Cell Mol Med. 2021.
[17] Delcourt V, et al. TB500/TB1000 and SGF1000. Drug Test Anal. 2023.
[18] Barton C, et al. Doping control analysis of TB-500. Drug Test Anal. 2013.
[19] Rahaman KA, et al. Simultaneous quantification of TB-500 and metabolites in rats. J Chromatogr B. 2024.
[22] Zhu Z, et al. Thymosin β4 promotes M2 polarization in NAFLD. J Inflamm Res. 2025.

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Peer-reviewed findings on TB-500, read warmly and honestly — the evidence gaps are noted alongside the findings, and no clinic sits behind this page.