Thymosin Alpha-1
Tissue & recoveryAlso known as Thymalfasin, Zadaxin, Tα1
Evidence tier
Regulator-reviewed human evidence
2 human trials · 2 reviews
- Researched since
- 1979
- Publications
- 864
- Mean purity
- 99.5%
- Vendors listing
- 12
American Peptides shows the highest mean assayed purity for Thymosin Alpha-1 at 99.8% across 1 lot record. Purity figures below come from the certificates named in each row.
Score breakdown
The score has two halves: the research base — how long the compound has been studied and how much has been published — and the quality of the evidence the market produces for it, aggregated across every vendor that carries it: assayed purity, lot-to-lot consistency, readable third-party certificates and those vendors’ review record. It measures the evidence base, not the merits or safety of the substance.
Studied since 1979 — 47 years of published research
How long the compound has been studied. Fifteen years or more of published literature earns full marks; a newer compound earns less.
864 publications indexed in PubMed
The volume of published literature located. Full marks at fifty or more publications.
Mean assayed purity 99.5% across 10 certificates
Average assayed purity on the certificates published by vendors that carry this compound. Full marks at 99.5%+, nothing at 95% or below.
±0.23 pts purity across lots, mean label deviation 9.1%
How tightly assayed purity and labeled-versus-actual mass hold across different lots. Rewards reproducible manufacturing.
12 of 12 listing vendors publish an accessible certificate policy
Whether the vendors carrying this compound publish per-lot certificates anyone can read without an account.
10 of 10 certificates from a recognised independent lab
Share of certificates issued by a recognised third-party testing lab rather than an unnamed or self-named one.
What is Thymosin Alpha-1?
A 28–amino-acid peptide derived from the thymus gland, studied for effects on immune modulation. An approved form is marketed in some countries as thymalfasin.
Studied in published research for immune modulation and infection response.
Regulatory status
Labeled by vendors for laboratory research use only. Not approved as a medicine in the United States, United Kingdom, or European Union.
What the research examines
The areas of published research this compound appears in. These describe what the literature has studied — never a claim of benefit, effect or suitability for any use.
Published research
The approved drug thymalfasin (Zadaxin) has been studied in humans for immune and infectious conditions. PepIndex does not evaluate clinical significance and does not describe administration.
- Thymosin alpha-1 — American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacist (2001)
Peer-reviewed article indexed in PubMed, published in American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists (2001).
- Aging and Thymosin Alpha-1 — International journal of molecular sciences (2025)
Peer-reviewed article indexed in PubMed, published in International journal of molecular sciences (2025).
- Thymosin alpha-1 treatment in chronic hepatitis B — Expert opinion on biological therapy (2015)
Peer-reviewed article indexed in PubMed, published in Expert opinion on biological therapy (2015).
- The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial — BMJ (Clinical research ed.) (2025)
Peer-reviewed article indexed in PubMed, published in BMJ (Clinical research ed.) (2025).
- A Pilot Trial of Thymalfasin (Thymosin-α-1) to Treat Hospitalized Patients With Hypoxemia and Lymphocytopenia Due to Coronavirus Disease 2019 Infection — The Journal of infectious diseases (2023)
Peer-reviewed article indexed in PubMed, published in The Journal of infectious diseases (2023).
- Clinical applications of thymosin alpha-1 — Cancer investigation (1994)
Peer-reviewed article indexed in PubMed, published in Cancer investigation (1994).
- Thymosin alpha 1 treatment for patients with sepsis — Expert opinion on biological therapy (2018)
Peer-reviewed article indexed in PubMed, published in Expert opinion on biological therapy (2018).
- Thymosin alpha 1 and HIV-1: recent advances and future perspectives — Future microbiology (2017)
Peer-reviewed article indexed in PubMed, published in Future microbiology (2017).
Indexed studies4 human-evidence of 4
- The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial — Human — controlled trial, 2025
To evaluate whether the immunomodulatory drug thymosin α1 reduces mortality in adults with sepsis. Multicentre, double blinded, placebo controlled phase 3 trial. 22 centres in China, September 2016 to December 2020. 1106 adults aged 18-85 years with a diagnosis of sepsis according to sepsis-3 criteria and randomly assigned in a 1:1 ratio to receive thymosin α1 (n=552) or placebo (n=554). A stratified block method was used for randomisation, and participants were s…
- Neoadjuvant immunochemotherapy plus thymalfasin in locally advanced gastric cancer: a prospective clinical trial — Human — controlled trial, 2026
Neoadjuvant immunochemotherapy has emerged as a promising strategy for locally advanced gastric and gastroesophageal junction (G/EGJ) adenocarcinoma, but a substantial proportion of patients derive limited benefit. Thymalfasin is an immunomodulatory peptide that may amplify antitumor immunity while attenuating toxicity. We conducted a phase II trial to evaluate anti-PD-1 plus SOX (S-1 and oxaliplatin) immunochemotherapy combined with thymalfasin as neoadjuvant treatment for G…
- Comprehensive Review of the Safety and Efficacy of Thymosin Alpha 1 in Human Clinical Trials — Systematic review, 2024
This study aims to assess the safety and efficacy of Thymosin Alpha 1 (Tα1) through a comprehensive narrative review of clinical studies involving over 11 000 human subjects in more than 30 trials. The focus was on Tα1's application in COVID-19, autoimmune conditions, and cancer treatment, with implications for future considerations. We systematically searched articles relevant to critical studies on COVID-19, infectious diseases, cancer, and autoimmune diseases i…
- Efficacy of thymosin α1 for sepsis: a systematic review and meta-analysis of randomized controlled trials — Meta-analysis, 2025
Despite advances in understanding sepsis pathophysiology and extensive research, few treatments effectively target its underlying immune dysfunction. Thymosin α1 (Tα1) shows promise as an immunomodulator, but its impact on sepsis remains unclear. A search strategy was designed to include any prospective clinical studies using Tα1 for assessing 28-day mortality in patients with sepsis, excluding combination therapy studies. We conducted trial sequential analy…
Evidence digest
What the research on Thymosin Alpha-1 actually shows
The indexed literature on Thymosin Alpha-1 includes human clinical or observational records (4 human-clinical or observational records). This digest describes the shape of that evidence and links the records behind it. It does not judge whether Thymosin Alpha-1 is safe or effective for any purpose, and nothing here is medical advice — the material sold by the vendors in this index is labeled for laboratory research use only.
3 things the literature does not establish →
PepIndex describes what literature exists. We do not interpret it, assess clinical significance, or publish quantities, protocols or instructions for use.
Vendor comparison
| Vendor | Score here | Price / mg | Certificates | Mean purity | Label deviation | Get it |
|---|---|---|---|---|---|---|
| Next Gen PeptidesISO/IEC 17025 | 93.897% | $4.50 (53%) | 2 | 99.6% | 5.8% | |
| PeptidePlugs | 89.790% | — | 2 | 99.5% | 7.3% | |
| Ascension Peptides | 85.186% | $5.00 (59%) | 1 | 99.4% | 29.4% | |
| Polaris PeptidesISO/IEC 17025 | 84.597% | $10.00 (118%) | 0 | — | — | |
| Northline LabsISO/IEC 17025 | 81.893% | $10.00 (118%) | 0 | — | — | |
| Good Science Bio | 79.275% | $4.50 (53%) | 0 | — | — | |
| American PeptidesISO/IEC 17025 | 77.1100% | $12.50 (147%) | 1 | 99.8% | 7.6% | |
| Licensed Peptides | 7789% | — | 1 | 99.1% | 19.2% | |
| Modern AminosISO/IEC 17025 | 74100% | — | 2 | 99.6% | 3.7% | |
| Simple Peptide | 7489% | — | 1 | 99.6% | 1.4% | |
| Mile High Compounds | 67.694% | $7.00 (82%) | 0 | — | — | |
| BioLongevity Labs | 61.674% | $13.00 (153%) | 0 | — | — |
Certificate records
| Vendor | Lot | Tested | Lab | Labeled | Assayed | Discrepancy | Purity | Source |
|---|---|---|---|---|---|---|---|---|
| PeptidePlugs | Red Cap | Freedom Diagnostics Testing | 10 mg | 10.18 mg | 1.8% | 99.2% | Vendor-published | |
| Modern Aminos | BX-P-L9B4 | Analysis FreedomDiagnostics | 10 mg | 10.67 mg | 6.7% | 99.7% | Vendor-published | |
| Next Gen Peptides | TA1-05 | ILS Laboratories | 10 mg | 10.54 mg | 5.4% | 99.5% | Vendor-published | |
| PeptidePlugs | SM-140-10 | Freedom Diagnostics Testing | 10 mg | 11.29 mg | 12.9% | 99.9% | Vendor-published | |
| Simple Peptide | THYMA10-052026-7 | Analysis FreedomDiagnostics | 10 mg | 10.14 mg | 1.4% | 99.6% | Vendor-published | |
| Next Gen Peptides | TA1-04 | ILS Laboratories | 10 mg | 10.62 mg | 6.2% | 99.7% | Vendor-published | |
| American Peptides | TA110-0318 | Excellence in HPLC-MS Analysis | 10 mg | 10.76 mg | 7.6% | 99.8% | Vendor-published | |
| Ascension Peptides | 33-01260229 | MZ Biolabs | 10 mg | 12.94 mg | 29.4% | 99.4% | Vendor-published | |
| Modern Aminos | BX-P-H7P4 | Freedom Diagnostics Testing | 5.44 mg | 5.4 mg | 0.7% | 99.5% | Vendor-published | |
| Licensed Peptides | 102415 | Vanguard Laboratory | 5 mg | 5.96 mg | 19.2% | 99.1% | Vendor-published |