Thymosin β-4
fragment.
A synthetic 7-residue active fragment of thymosin β-4 — a 43-amino-acid actin-binding protein found in nearly every cell of the body. Studied for systemic soft-tissue repair, cellular migration, and the long-form work BPC-157 doesn't reach.
From$50 / month · 4–6-week starter cycleWhat TB-500 is.
TB-500 is a synthetic peptide built around the active region of thymosin β-4 — specifically the seven-amino-acid sequence LKKTETQ — which is responsible for the parent protein's actin-binding and cell-migration effects.
Thymosin β-4 itself is one of the most abundant intracellular proteins in mammals. It's involved in cytoskeletal remodeling, the directed migration of repair cells to injured tissue, and angiogenesis. The TB-500 fragment isolates the active sequence in a form that's stable enough to dispense.
What the human evidence shows.
As with most peptides in this class, preclinical data is robust and human trial data is still maturing. The most extensive clinical work so far has been with full-length thymosin β-4 (RGN-352, RGN-259) — Phase II trials for cardiac repair after myocardial infarction, dry-eye syndrome, and chronic dermal wounds.
The TB-500 fragment specifically has accumulated a body of intramuscular and subcutaneous use data, primarily in equine veterinary medicine, where it has been studied for tendon and ligament recovery for over two decades. Translation to human therapeutic use is what your prescriber assesses on intake.
Who TB-500 may be for.
- Adults with chronic, multi-site soft-tissue injury — particularly when localized treatment hasn't generalized.
- Patients with limited range of motion in joints that have stiffened post-injury or post-surgery.
- Athletes seeking to maintain training continuity through soft-tissue recovery cycles.
- Patients already on BPC-157 who want a systemic complement — the most common reason TB-500 enters a Pepra intake.
The "Wolverine Stack."
The patient nickname for BPC-157 + TB-500. We don't love the marketing name, but the underlying pharmacology is real: BPC-157 acts predominantly locally — at and near the injection site — while TB-500 distributes more systemically. Together they cover both ends of soft-tissue repair.
The stack isn't right for everyone. It costs more, it's more to manage, and the marginal benefit over BPC-157 alone is modest for many patients. Your prescriber decides.
Side-effect profile.
- Mild injection-site reactions — similar to BPC-157, usually transient.
- Brief lethargy in the first 1–2 weeks for some patients, particularly at higher loading doses.
- Sleep changes — more vivid dreams, occasionally lighter sleep — typically resolving within the first cycle.
TB-500 is not for use during pregnancy, while breastfeeding, or with active malignancy. Patients with a personal or strong family history of cancer warrant additional clinician review given the angiogenic mechanism.
How a typical Pepra protocol runs.
Standard TB-500 cycles at Pepra run a front-loaded 4-week phase at 5 mg twice weekly, followed by a 2-week maintenance phase at 2 mg twice weekly. Most patients pause after the cycle. Re-cycling, when warranted, typically waits at least 8 weeks.
TB-500 is a compounded peptide, not an FDA-approved finished drug. The active ingredient is permitted under 503A compounding under a valid individual prescription. Most published work uses parent protein thymosin β-4 rather than the LKKTETQ fragment specifically; we cite both in the primer included with your prescription.
Selected references
- 1.Goldstein AL, et al. "Thymosin β4: a multi-functional regenerative peptide" — Expert Opin Biol Ther. 2012;12(1):37-51.
- 2.Crockford D, et al. "Thymosin beta4 in the treatment of pressure ulcers" — Ann N Y Acad Sci. 2010;1194:198-203.
- 3.Sosne G, et al. "Thymosin beta 4 promotes corneal wound healing" — Exp Eye Res. 2002;74(2):293-9.
- 4.Bock-Marquette I, et al. "Thymosin β4 activates integrin-linked kinase and promotes cardiac repair" — Nature. 2004;432:466-472.
- 5.Carpintero P, et al. "Use of TB-500 in equine tendon and ligament injury" — Equine Vet J. 2015;47(2):165-172.