Short answer: Both are unapproved peptides whose evidence is mostly from animals. A 2026 systematic review found only 3 human BPC-157 studies, with 30 people in total and very low certainty.1 TB-500 is a 7-amino-acid fragment (Ac-LKKTETQ) of thymosin beta-4 whose biological effects have not been documented in humans.2 Human trials exist only for full-length thymosin beta-4.
| BPC-157 | TB-500 | |
|---|---|---|
| What it is | 15-amino-acid synthetic peptide based on a gastric protein fragment | Ac-LKKTETQ, a 7-amino-acid fragment from the active site of thymosin beta-42 |
| Approval status | Not FDA approved | Not FDA approved |
| FDA compounding status (2026) | Moved from Category 2 to "nominated but withdrawn" (nominators withdrew); FDA cites limited safety information3 | Same: moved to "nominated but withdrawn"3 |
| Advisory committee | Reviewed by FDA's compounding advisory committee in July 2026; non-binding, no FDA decision yet4 | Reviewed at the same meeting4 |
| Human studies | 3 small studies, 30 people: knee pain chart review (16), bladder pilot (12), IV safety pilot (2)1 | None for TB-500 itself. Full-length thymosin beta-4 has phase 1 IV safety trials and eye and wound trials5 |
| Doses reported in humans | 10 mg total injected into the bladder wall;6 10 mg then 20 mg IV7 | None for TB-500 |
| Half-life | Under 30 minutes in rats and dogs (IV, IM); no human value8 | No value for TB-500. Full-length thymosin beta-4 IV: 0.5 to 2.08 hours5 |
| Typical vial sizes | 5 or 10 mg powder | 2, 5 or 10 mg powder |
| Sport | WADA S0 (non-approved substances) | WADA S2 (thymosin beta-4 and derivatives, e.g. TB-500) |
A 2026 systematic review of these concluded the evidence is "largely limited to animal models" with very low certainty.1 A 2025 scoping review called human data "extremely limited."10 Most BPC-157 research uses rats, often at microgram-per-kilogram doses, such as 10 mcg/kg in a tendon study.11
No. Thymosin beta-4 is a full-length protein; TB-500 is a 7-amino-acid piece of it. The human trials people cite are for full-length thymosin beta-4: IV phase 1 safety studies with no dose-limiting toxicity,512 eye-drop trials with mixed results (a phase 3 neurotrophic keratopathy trial with 18 people did not reach significance),13 and a topical gel for venous ulcers.14 A 2024 doping-control paper notes that TB-500's own biological effects "have not been documented."2
In 2026 FDA moved both from its Category 2 list (substances that may present significant safety risks in compounding) to a "nominated but withdrawn" list, because the nominators withdrew them, not because FDA cleared them.3 FDA's compounding advisory committee reviewed both in July 2026. Its vote is advisory, and FDA has not made a decision. Neither is an approved drug.4