Thymosin alpha-1 research: studies, doses and safety
An immune-signaling peptide with overseas approvals and mixed trial results.
Also called: Thymalfasin, TA1, Tα1, Thymosin α1, Zadaxin.
Immune peptides · Synthetic 28-amino-acid thymic immune modulator · Evidence: Approved drug.
Major sepsis and hepatitis C trials found no clear benefit. Hepatitis B findings remain uncertain, and reviews reuse some of the same trial data.
Key studies
- Early injection dose study (1983): Short-lived immune-test changes did not establish an anticancer benefit. (source)
- Absorption and half-life (1999): Formulation affects exposure; a short blood half-life does not set an effective dosing interval. (source)
- Early hepatitis B pilot (1991): A tiny mixed-product pilot cannot isolate TA1 benefit. (source)
- Hepatitis B versus interferon (1996): This small trial did not show a clear advantage over interferon. (source)
- Hepatitis B: six or twelve months (1998): A delayed viral response favored six months of dosing in this small trial. (source)
- Hepatitis B placebo trial (1999): The placebo-controlled phase 3 trial did not confirm efficacy. (source)
Related to Thymosin alpha-1
- VIP: A blood-vessel and immune signal studied in lung disease; nasal CIRS benefits remain unproven.
- BPC-157: An experimental repair peptide with mostly animal evidence and a few small human reports.
- TB-500: A short piece of thymosin beta-4 with no proven repair benefit in humans.
- GHK-Cu: A copper-binding skin peptide with small topical studies and untested systemic injections.
- MOTS-c: A peptide the body makes; injection benefits and safety remain unproven.
- Epitalon: A peptide with telomerase effects in cells, but no proof that people live longer.
Sources
- 21 CFR 216.23 — Bulk drug substances that can be used to compound drug products in accordance with section 503A of the Federal Food, Drug, and Cosmetic Act., Office of the Federal Register · eCFR · 2026
- 503B Bulk Drug Substances List, FDA · FDA · 2026
- Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act, FDA · FDA · 2026
- Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, FDA · FDA · 2026
- MHRA Products | Home, MHRA · MHRA · 2026
- TGA strengthens compliance focus on unapproved peptide products as part of evolving risk response, Therapeutic Goods Administration · TGA · 2026
- The 2026 Prohibited List, World Anti-Doping Agency · WADA · 2026
- The Prohibited List, World Anti-Doping Agency · World Anti-Doping Agency · 2026
- Think twice before injecting peptides bought online: unauthorized products can seriously harm you, Health Canada · Health Canada · 2026
- Thymosin Alpha 1 [Zadaxin], Singapore National Drug Formulary · 2026
- Bulk Drug Substances Nominated for Use in Compounding Under Section 503B of the Federal Food, Drug, and Cosmetic Act, FDA · FDA · 2025
- December 4, 2024 Pharmacy Compounding Advisory Committee (PCAC) Meeting, FDA · 2024
- December 4, 2024 Pharmacy Compounding Advisory Committee Meeting, FDA · 2024
- Fraudulent Coronavirus Disease 2019 (COVID-19) Products, FDA · 2020
- Public summary of positive opinion for orphan designation of thymalfasin for the treatment of hepatocellular carcinoma, European Medicines Agency
Sources checked: 2026-10-18.
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