- What it is: A synthetic copy of Thymosin Alpha-1 (TA1), a 28-amino-acid peptide from the thymus.
- Research areas: Severe sepsis in the ICU, chronic hepatitis B trials, and broader immune-modulation research.
- Evidence level: Randomized human trials exist, in sepsis and hepatitis B. The catch is the results are mixed, and the largest recent trial came back close to a tie.
- The short version: Thymosin Alpha-1 has been tested in randomized human trials in sepsis and hepatitis B. The record is real, but it is mixed, and none of it is a green light to use anything.
What it is
Thymosin Alpha-1 is a synthetic copy of a 28-amino-acid peptide first isolated from calf thymus tissue. It was isolated and sequenced in 1977 in Allan Goldstein’s lab. Its generic drug name is thymalfasin.
Specs at a glance. Reference values for the compound named on the label, from PubChem or KEGG. They describe the compound, not a measurement of the vial you receive. Molecular weight is the free base (the peptide alone, without a salt). Synthetic peptides are usually supplied as a salt such as acetate or TFA, and the salt in this vial has not been confirmed.
| Compound | Thymosin Alpha-1 (thymalfasin) |
|---|---|
| Sequence | Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN-OH (28 aa, N-acetyl) |
| Molecular formula | C129H215N33O55 |
| Molecular weight | 3108.3 g/mol (average, free base) |
| CAS number | 62304-98-7 |
| Reference record | PubChem CID 16130571 |
| Form | Lyophilized (freeze-dried) powder in one sealed vial |
| Vial size | 10 mg per vial |
| Storage (dry powder) | -20°C or colder, long term. Keep the vial sealed and away from light. |
| Lab report | Janoshik Analytical, May 2026. Ordered by the supplier, not by Etched Research. The report carries no lot number, so it is not matched to the vial you receive. Results on this page ↓ · All lab reports → |
What the evidence is
Thymosin Alpha-1 has more human randomized trials behind it than most compounds in this category, mostly in hospital patients with sepsis. The record is mixed. The largest and best-controlled trial found no clear difference from placebo.
| Study | Type | Who | What was given | What it measured | What it found |
|---|---|---|---|---|---|
| Mutchnick et al., Journal of Viral Hepatitis, 1999 | Human, phase 3, placebo-controlled | 97 adults with chronic hepatitis B | 1.6 mg twice weekly for 6 months | Virus cleared from the blood and stayed cleared at 12 months | 14% vs 4% on placebo, not statistically significant. The authors said it did not confirm earlier positive studies |
| Wu et al. (ETASS), Critical Care, 2013 | Human, randomized, single-blind, no placebo | 361 ICU patients with severe sepsis, 6 hospitals in China | Added to standard ICU care, compared with standard care alone | Death from any cause at 28 days | 26.0% vs 35.0%. Borderline: the range of likely effect included no difference |
| Wu et al. (TESTS), BMJ, 2025 | Human, phase 3, double-blind, placebo-controlled | 1,106 adults with sepsis, 22 centres in China | Every 12 hours for 7 days | Death from any cause at 28 days | 23.4% vs 24.1% on placebo. No clear difference |
| Gu et al., Frontiers in Cellular and Infection Microbiology, 2025 | Pooled analysis of 11 randomized trials | 1,927 patients with sepsis | Varied by trial | Death at 28 days | Lower overall, but no clear difference when limited to the higher-quality or multicenter trials. The authors said more patients are needed |
Last reviewed 2026-09-23. TESTS was funded in part by SciClone Pharmaceuticals. The mechanism work behind these trials, and what none of it establishes, is on the full research summary →
Lab reference
Janoshik Analytical tested Thymosin Alpha-1 10mg from supplier stock in May 2026. The sample measured 99.901% purity and 12.31 mg of peptide against the 10 mg label. See it on the lab reference page →
What that report does not cover: it is a reference test of the compound from supplier stock, not a test of the vial in your order. No endotoxin, sterility or heavy-metal result is published for it.
Storage and shipping
Ships as lyophilized powder in a sealed vial. Store the powder frozen at -20°C, away from light. US addresses only. Shipping costs and cutoff times →
Questions about Thymosin Alpha-1
Is Thymosin Alpha-1 the same thing as thymalfasin?
Yes. Thymalfasin is the generic drug name for thymosin alpha-1. TA1 and Tα1 are the short forms used in papers.
Is there human data?
Yes, three trials and one pooled analysis are listed above. The largest trial (1,106 people with sepsis) found no clear difference from placebo, and the hepatitis B trial did not reach statistical significance. The most positive result came from a smaller trial without a placebo arm.
Where can I buy Thymosin Alpha-1 for research?
Etched Research sells Thymosin Alpha-1 on this page as a 10mg vial of lyophilized powder, for laboratory research use only, shipped to US addresses. Where an independent laboratory report exists for a compound, the measurements are published on the lab reference page, including the compounds we hold no report for.
Does Etched Research sell Zadaxin?
No. Zadaxin is a prescription drug whose active ingredient is thymalfasin. It is sold in some countries outside the US. The FDA has approved no drug containing thymosin alpha-1. Etched Research sells Thymosin Alpha-1 as a research compound for laboratory use only. It is not for human use.
Shipping, eligibility and what comes in the box: store FAQ →
For research use only. Not for human consumption.
