Head to head
TB-500 against Pentadeca Arginate
Two products whose evidence belongs to other molecules. One is a fragment sold on the parent peptide's trials; the other is a salt form sold on BPC-157's animal literature. Neither has a study of its own.
Column A
TB-500TB-500 (N-acetylated thymosin beta-4 fragment 17 to 23, Ac-LKKTETQ)
A seven-residue fragment of thymosin beta-4 sold under a research name. No published study has given TB-500 to people; the clinical trial record usually quoted for it belongs to the full 43-residue parent peptide, which is a different molecule.
Column B
Pentadeca ArginatePentadeca Arginate (PDA, pentadecapeptide arginate)
The same 15 amino acid sequence as BPC-157 with an arginine salt instead of acetate, created as a compounding workaround; it has no studies of its own and inherits BPC-157's animal-only evidence.
Side by side, on the facts we can check
| Attribute | TB-500 | Pentadeca Arginate |
|---|---|---|
| Category | Healing & Recovery | Healing & Recovery |
| FDA status | Not FDA-approved. Removed from Category 2 (April 2026); PCAC voted 8 to 6, one abstention, to recommend for compounding (July 2026) against the FDA reviewers' recommendation; awaiting FDA action | Not approved; not an FDA-recognized distinct substance |
| Half-life | Not established in humans | No human pharmacokinetics for either salt form |
| Molecular weight | 889.0 Da (free base); 949.1 Da (acetate) | 1,419.5 Da for the BPC-157 pentadecapeptide it is based on; supplied as the arginate salt, which is heavier |
| Mechanism | The LKKTET sequence inside the fragment is the actin-binding region of thymosin beta-4. The hypothesis is that it binds monomeric G-actin the way the parent peptide does, supporting actin filament turnover, cell migration and angiogenesis at an injury site. FDA's review notes that the wound-healing work was done mostly with the non-acetylated heptapeptide or with the full parent peptide, and that those results cannot be extrapolated directly to the acetylated fragment sold as TB-500. | Presumed identical to BPC-157: FAK-paxillin, VEGFR2 and nitric-oxide signaling supporting angiogenesis and tissue repair in animal models. |
| Human studies cited | 2 | 0 |
| Legal status, US | Not approved; research use only | Not approved; sold 'for research use only' |
Frequently asked questions
What is the difference between TB-500 and Pentadeca Arginate?
TB-500: A seven-residue fragment of thymosin beta-4 sold under a research name. No published study has given TB-500 to people; the clinical trial record usually quoted for it belongs to the full 43-residue parent peptide, which is a different molecule. Pentadeca Arginate: The same 15 amino acid sequence as BPC-157 with an arginine salt instead of acetate, created as a compounding workaround; it has no studies of its own and inherits BPC-157's animal-only evidence.
Which has stronger research evidence, TB-500 or Pentadeca Arginate?
This database does not grade compounds. It counts what was run in people: 2 of the 9 studies cited on the TB-500 profile were human work, against 0 of 3 for Pentadeca Arginate. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are TB-500 and Pentadeca Arginate FDA-approved?
TB-500: Not FDA-approved. Removed from Category 2 (April 2026); PCAC voted 8 to 6, one abstention, to recommend for compounding (July 2026) against the FDA reviewers' recommendation; awaiting FDA action. Pentadeca Arginate: Not approved; not an FDA-recognized distinct substance.
Related posts
Blog articles that cover TB-500 or Pentadeca Arginate, newest first.
- Healing & Recovery / Sep 8, 2026 / 9 minPeptides for Joint Pain: BPC-157, TB-500, Lorecivivint, Pentosan and Collagen Peptides, Evidence Tiered
- Healing & Recovery / Sep 8, 2026 / 8 minPeptides for Gut Health: BPC-157, KPV and Larazotide Ranked by Human Evidence
- Safety / Sep 8, 2026 / 9 minPeptide Side Effects by Class: What Is Documented, What Is Anecdotal
- Safety / Sep 8, 2026 / 8 minHow to Read a Peptide Certificate of Analysis: HPLC Purity, Mass Spec Identity, Endotoxin, and Janoshik Verification
Reviewed Sep 2026. This page sets two published records side by side. It is educational, it is not medical advice, and it contains no dosing protocols or recommendations for personal use.