FDA compounding status
Thymosin beta-4 (full-length)
Full-length thymosin beta-4 is not FDA-approved, and there is no pathway for a US pharmacy to compound it today. FDA's 503A and 503B category documents have no entry for it, and it is on neither bulks list. TB-500 is a different substance (a fragment), and its status does not transfer to the full-length molecule.
Full-length thymosin beta-4, not the LKKTETQ fragment sold as TB-500.
Checked against the primary sources on .
The record
- FDA status
- No compounding pathway today.
- Compounding basis
- No compounding pathwayNo facility type may compound this substance today.
- FDA advisory committee
- Not reviewed
- Sport (WADA 2026)
- Prohibited at all times under WADA class S2.3 (growth factors and growth factor modulators).
- Offered by PEPLUX
- No
- Checked on
Basis
What this status traces to.
FDA's 503A categories document of May 14, 2026 and 503B categories document of March 21, 2025 have no entry for full-length thymosin beta-4. It is not on the 503A bulks list (21 CFR 216.23) or the 503B bulks list, it is not FDA-approved, and FDA's Pharmacy Compounding Advisory Committee has not reviewed it.
Primary sources
- FDA 503A categoriesBulk drug substances nominated for use in compounding under section 503A (categories), updated May 14, 2026Document dated . Checked .
- FDA 503B categoriesBulk drug substances nominated for use in compounding under section 503B (categories), updated March 21, 2025Document dated . Checked .
- FDA503B Bulk Drug Substances ListDocument dated . Checked .
- eCFR21 CFR 216.23, Bulk drug substances that can be used to compound drug productsDocument dated . Checked .
- WADAWorld Anti-Doping Code, 2026 Prohibited ListDocument dated . Checked .
Context
A removal or a committee vote is not a listing.
Removal from FDA's Category 2 is not FDA approval and not a listing. FDA removed several peptides from its 503A Category 2 after their nominators withdrew the nominations, not because the substances were found safe: BPC-157, TB-500, MOTS-c, semax and epitalon among others (removal noticed April 15, 2026, effective after 7 days), and CJC-1295 and ipamorelin earlier (removal notice dated September 27, 2024). None was added to the 503A bulks list, so none has a compounding pathway today. A favorable vote by FDA's Pharmacy Compounding Advisory Committee is a recommendation, not a listing: nothing changes unless FDA publishes a final rule.
FDA advisory committee
FDA's Pharmacy Compounding Advisory Committee has not reviewed it.
If you are subject to anti-doping rules
Prohibited at all times under WADA class S2.3 (growth factors and growth factor modulators).
Common questions
Thymosin beta-4 (full-length), answered plainly.
- What is the FDA compounding status of Thymosin beta-4 (full-length)?
- Full-length thymosin beta-4 is not FDA-approved, and there is no pathway for a US pharmacy to compound it today. FDA's 503A and 503B category documents have no entry for it, and it is on neither bulks list. TB-500 is a different substance (a fragment), and its status does not transfer to the full-length molecule.
- What does the status of thymosin beta-4 (full-length) trace to?
- FDA's 503A categories document of May 14, 2026 and 503B categories document of March 21, 2025 have no entry for full-length thymosin beta-4. It is not on the 503A bulks list (21 CFR 216.23) or the 503B bulks list, it is not FDA-approved, and FDA's Pharmacy Compounding Advisory Committee has not reviewed it. Checked against the primary sources on October 13, 2026.
- Does a Category 2 removal or an advisory committee recommendation change the status of thymosin beta-4 (full-length)?
- Removal from FDA's Category 2 is not FDA approval and not a listing. FDA removed several peptides from its 503A Category 2 after their nominators withdrew the nominations, not because the substances were found safe: BPC-157, TB-500, MOTS-c, semax and epitalon among others (removal noticed April 15, 2026, effective after 7 days), and CJC-1295 and ipamorelin earlier (removal notice dated September 27, 2024). None was added to the 503A bulks list, so none has a compounding pathway today. A favorable vote by FDA's Pharmacy Compounding Advisory Committee is a recommendation, not a listing: nothing changes unless FDA publishes a final rule.
- Does PEPLUX offer thymosin beta-4 (full-length)?
- Thymosin beta-4 (full-length) is not FDA-approved, and there is no lawful pathway for a US pharmacy to compound it today. Its safety and effectiveness in people have not been established. PEPLUX does not offer, prescribe or sell it. This page explains its regulatory status and is not a recommendation to use it.
- Is thymosin beta-4 (full-length) prohibited in sport?
- Prohibited at all times under WADA class S2.3 (growth factors and growth factor modulators).