# TB-500 Dosage in the Research Literature — Preclinical and Clinical Data > TB-500 dosage in the research literature: rodent protocols 2–12 mg/kg, equine field use, and human Phase I IV dosing of full-length thymosin beta-4. All data indexed from published sources. ## TB-500 Dosage in the Research Literature TB-500 dosage data in the peer-reviewed literature comes from three model categories: rodent preclinical studies, equine field administration (documented through doping-control analysis), and human Phase I trials of full-length thymosin beta-4 (not the TB-500 fragment specifically). No validated human dosing protocol for TB-500 (Ac-LKKTETQ) exists in indexed literature as of 2026. This page indexes what was administered, to which species, by which route, at what dose — as reported in cited studies. It does not constitute a dosing recommendation. TB-500 is not FDA-approved for any human indication. ## TB-500 Dose Ranges in Preclinical Literature Rodent studies span a wide dose range depending on the tissue model and species: **Dermal wound healing (rat, mouse):** Topical or intraperitoneal administration. Malinda et al. (1999) did not report a single dose-escalation curve but demonstrated dose-dependent effects; the LKKTETQ fragment was active at approximately 50 nM in vitro [3][1]. **Skeletal muscle (mouse, dystrophin-deficient):** 150 µg flat dose, twice weekly, for 6 months via systemic injection — the mdx model [9]. **Neurological (rat, embolic stroke):** 2–12 mg/kg systemically. Morris et al. (2014) modeled an optimal dose of 3.75 mg/kg for neurological outcome at 14 and 56 days [17]. **Neurological (rat, TBI):** Systemic injection initiated 6 hours post-injury; specific mg/kg not consistently reported across abstracts [18]. **Equine:** TB-500 (N-acetylated LKKTETQ) was detected in post-administration field samples at concentrations consistent with milligram-range intravenous or intramuscular use, but specific equine dose protocols are not published in indexed literature — the published work is doping-control detection methodology [2]. **Human Phase I (full-length Tβ4, synthetic):** 42–1260 mg IV in single and 14-day multiple-dose regimens. Dose-proportional pharmacokinetics; no dose-limiting toxicities [13]. **Human Phase I (full-length Tβ4, recombinant NL005):** 0.05–25.0 µg/kg IV single dose; 0.5, 2.0, and 5.0 µg/kg IV once daily for 10 days. Well tolerated; no serious adverse events [21]. These are research doses from specific study designs and species. They do not constitute dosing guidance for any human use. ## TB-500 Study Duration in the Literature Protocol durations in the published literature: **Wound healing (rodent):** Most studies run 14–21 days. The 4-day and 7-day time points in Malinda et al. (1999) were within a 21-day overall study window [3]. **Cardiac (mouse):** Assessments typically at 2–4 weeks post-infarction [4][5]. **Neurological (rat):** 56-day follow-up in the stroke model [17]; multi-week assessment in the TBI model [18]. **Muscle (mouse, mdx):** 6-month continuous dosing [9]. **Human Phase I (synthetic Tβ4):** 14-day repeated dosing in the multi-dose cohort [13]. **Human Phase I (recombinant Tβ4):** 10-day daily dosing in the multiple-dose cohort [21]. No validated human protocol duration exists for TB-500. Animal study durations reflect the specific outcome being measured (acute wound closure vs. chronic fibrotic remodeling vs. neurological recovery) and should not be interpreted as dosing-duration guidance. ## TB-500 Injection Frequency in Preclinical Studies Most animal studies use 2–3 administrations per week rather than daily: - The 6-month mdx mouse study used twice-weekly systemic injection [9]. - The Morris et al. (2014) stroke study used systemic administration; frequency is not always reported in abstracts [17]. - Philp and Kleinman (2010) reviewed multiple animal models: topical, subcutaneous, intraperitoneal, and systemic routes — 2–3 times weekly was the predominant schedule across wound healing and cardiac models [20]. Daily dosing appeared in the human Phase I multi-dose studies: once-daily IV for 10 days in Wang et al. (2021) [21] and daily-equivalent sub-groupings in Ruff et al. (2010) [13]. Daily protocols are not the predominant design in animal studies. Frequency in the literature reflects study design choices, not optimal therapeutic scheduling. No human frequency data for TB-500 (the heptapeptide fragment) exists. ## Route and Site of TB-500 Administration in Studies Five routes appear in the published literature: 1. **Topical (dermal/ocular):** Used in wound-healing and corneal studies in rats and mice [3][11]. 2. **Intraperitoneal:** Common in rodent wound healing and muscle models — efficient systemic delivery in small rodents [3][10]. 3. **Subcutaneous:** Reported in rodent preclinical models across multiple tissue targets [20]. 4. **Intravenous:** Used in all published human Phase I trials of full-length Tβ4 [13][21], and in the equine doping-detection study [2]. 5. **Intramuscular:** The equine field-use route, inferred from doping-detection methodology [2]. Thymosin beta-4 operates as a systemic signaling molecule — local injection at the site of injury is not required in the published protocols. The mechanism (actin sequestration, ILK-Akt activation) is initiated systemically and mediated by receptor-downstream signaling at target tissues. See the full [injection route comparisons](/dosage#injection-routes) below. ## Injection Route Comparisons in TB-500 Studies Route comparison within a single study is rare in the published TB-500 and Tβ4 literature. The predominant routes by model type: | Model | Predominant route | Reference | |---|---|---| | Rodent dermal | Topical or IP | Malinda 1999 [3] | | Rodent corneal | Topical ocular | Sosne 2002 [11] | | Rodent cardiac | Systemic (IP or IV) | Bock-Marquette 2004 [4] | | Rodent neurological | Systemic (IV or IP) | Morris 2014 [17] | | Rodent muscle | IP or systemic | Spurney 2010 [9] | | Equine | IV or IM (field) | Ho et al. 2012 [2] | | Human Phase I | IV only | Ruff 2010 [13], Wang 2021 [21] | No controlled intravenous vs. subcutaneous vs. intramuscular comparison study for TB-500 in any species has been published in indexed literature. Route choice in animal models is driven by species and study-design convenience; human-validated route data does not exist for the TB-500 heptapeptide fragment. ## TB-500 Half-Life and Pharmacokinetics No published plasma half-life data for the TB-500 heptapeptide fragment (Ac-LKKTETQ) in any species appears in indexed literature. For full-length thymosin beta-4, pharmacokinetic data from the Ruff et al. (2010) human Phase I trial shows dose-dependent half-life: approximately 0.95 hours at 42 mg IV, increasing to approximately 2.1 hours at 1260 mg IV — dose-proportional kinetics with no accumulation [13]. The Wang et al. (2021) Phase I trial of recombinant Tβ4 (NL005) similarly showed dose-proportional pharmacokinetics with no accumulation on 10-day daily dosing at 0.5–5.0 µg/kg [21]. TB-500 at 839 Da is substantially smaller than full-length Tβ4 at 4921 Da. Smaller peptides generally clear more rapidly via renal filtration; on pharmacokinetic grounds, the TB-500 fragment is expected to have a shorter plasma half-life than the parent molecule. However, tissue effects may outlast plasma levels: receptor-mediated downstream signaling (ILK-Akt activation, MMP induction) persists after peptide clearance. N-terminal acetylation of TB-500 confers resistance to aminopeptidase degradation, which would extend functional half-life relative to an unmodified heptapeptide. Precise data on the TB-500 half-life awaits dedicated pharmacokinetic studies. --- The TB-500 research record, ordered — twenty-two findings plotted by evidence class, each citation indexed, no clinic and no vendor behind the grid.