Vendor comparison · 2026
Thymosin Alpha-1 vendors: 20 compared on COAs and price
Tissue & recoveryAlso known as Thymalfasin, Zadaxin, Tα1
Evidence tier
Regulator-reviewed human evidence
2 human trials · 2 reviews
- Vendors carrying it
- 20
- 18 with a listed price
- Vendors with checkable COAs
- 7
- 7 publish any certificate
- Lots tested
- 11
- 11 naming a checkable lab
- Independent assays
- 0
- none on file yet
- Newest assay
- 24 Sept 2026
- oldest 10 Dec 2025
- Laboratories named
- 5
- most often Freedom Diagnostics Testing
- Median label gap
- 6.2%
- 27% of lots within 5% of label
- Median purity
- 99.44%
- 11 of 11 lots at 99% or above
- Lowest price per mg
- $3.90
- peer median $7.60
- Publications located
- 864
- researched since 1979
Source: PepIndex, an independent index of research-peptide vendors. No vendor can pay for a rank, every score is computed by a published formula, and every figure links to the document it was read from.
Next Gen Peptides has the most checkable Thymosin Alpha-1 testing in this index: 2 lots assayed by ILS Laboratories, the newest on 3 Sept 2026. The lowest listed price is $3.90 per mg at Eternal Peptides, against a peer median of $7.60. 20 vendors carrying Thymosin Alpha-1 are compared below. 7 publish at least one certificate naming a checkable laboratory, 11 lot records are on file, and none is an independently commissioned assay. Figures are PepIndex's own: it is an independent index of research-peptide vendors, no vendor can pay for a rank, and each figure links to the certificate it was read from.
Every vendor carrying Thymosin Alpha-1
| # | Vendor | Score here | Price / mg | Lots | Newest test | Laboratory | Mean purity | Label gap | Reports |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Next Gen PeptidesISO/IEC 17025 | 93.697% | — | 2 / 2 | ILS Laboratories | 99.4% | 5.6% | ||
| 2 | Ascend ScienceISO/IEC 17025 | 92.694% | $5.25 (69%) | 0 | — | — | — | — | |
| 3 | Amino ClubISO/IEC 17025Age-gated COAs | 92.598% | $4.00 (53%) | 0 | — | — | — | — | |
| 4 | PeptidePlugs | 88.594% | $6.00 (79%) | 2 / 2 | Freedom Diagnostics Testing | 99.5% | 7.3% | ||
| 5 | CuroISO/IEC 17025 | 88.197% | $6.00 (79%) | 0 | — | — | — | — | no reportVisit site |
| 6 | Hydro Research PeptidesISO/IEC 17025 | 85.989% | — | 1 / 1 | ILS Laboratories | 99.3% | 6.1% | ||
| 7 | Ascension Peptides | 82.789% | $7.10 (93%) | 2 / 2 | Kovera Labs, MZ Biolabs | 99.4% | 22.2% | ||
| 8 | Modern AminosISO/IEC 17025COAs need an account | 79.897% | $8.00 (105%) | 2 / 2 | Freedom Diagnostics Testing | 99.6% | 3.7% | ||
| 9 | Simple Peptide | 76.592% | $8.60 (113%) | 1 / 1 | Freedom Diagnostics Testing | 99.6% | 1.4% | ||
| 10 | Good Science Bio | 74.571% | $4.50 (59%) | 0 | — | — | — | — | no reportVisit site |
| 11 | Evo Labs Research | 73.487% | $7.20 (95%) | 0 | — | — | — | — | no reportVisit site |
| 12 | Protide HealthAge-gated COAs | 70.592% | $10.50 (138%) | 0 | — | — | — | — | no reportVisit site |
| 13 | Eternal Peptides | 6963% | $3.90 (51%) | 0 | — | — | — | — | no reportVisit site |
| 14 | Bench Grade Peptides | 68.989% | $12.10 (159%) | 0 | — | — | — | — | no reportVisit site |
| 15 | Mile High Compounds | 62.191% | $7.00 (92%) | 0 | — | — | — | — | no reportVisit site |
| 16 | Licensed Peptides | 6187% | $12.40 (163%) | 1 / 1 | Vanguard Laboratory | 99.1% | 19.2% | ||
| 17 | BioLongevity Labs | 54.572% | $13.00 (171%) | 0 | — | — | — | — | no reportVisit site |
| 18 | GenX Peptides | 52.869% | $14.67 (193%) | 0 | — | — | — | — | no reportVisit site |
| 19 | True Research Labs | 5168% | $12.90 (170%) | 0 | — | — | — | — | no reportVisit site |
| 20 | Biotech Peptides | 49.160% | $13.00 (171%) | 0 | — | — | — | — | no reportVisit site |
Independent assays
No independently commissioned assay of Thymosin Alpha-1 is on file. All 11 records below were published by the vendor that sells the product, naming the laboratory shown. PepIndex does not yet commission its own assays, so nothing on this page establishes what is in a vial beyond the vendor’s own certificate. A record moves into this section the moment an assay commissioned by anyone other than the seller is indexed.
What the certificates show
11 of 11 lots at 99% or above; median 99.44%.
| Range | lots |
|---|---|
| <95% | 0 |
| 95–97% | 0 |
| 97–98% | 0 |
| 98–99% | 0 |
| 99–99.5% | 7 |
| ≥99.5% | 4 |
27% of lots within 5% of the labelled mass; median gap 6.2%.
| Range | lots |
|---|---|
| ≤2% | 3 |
| 2–5% | 0 |
| 5–10% | 4 |
| 10–20% | 3 |
| >20% | 1 |
18 vendors, $3.90 to $14.67; median $7.60.
| Range | vendors |
|---|---|
| $0–$5.00 | 3 |
| $5.00–$10.00 | 8 |
| $10.00–$15.00 | 7 |
Purity and mass are read from each certificate as published; the label gap is |labeled − assayed| ÷ labeled. Every value behind these bars is in the certificate table below.
Laboratories used
| Laboratory | Lots | Vendors | Share | Verify |
|---|---|---|---|---|
| Freedom Diagnostics TestingUS | 5 | 3 | 45% | Public lookup |
| ILS LaboratoriesUS | 3 | 2 | 27% | Public lookup |
| Kovera Labs | 1 | 1 | 9% | No public lookup found |
| MZ BiolabsUS | 1 | 1 | 9% | No public lookup found |
| Vanguard LaboratoryUS | 1 | 1 | 9% | No public lookup found |
Every certificate record
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 11 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 9.5%
How tightly assayed purity and labeled-versus-actual mass hold across different lots. Rewards reproducible manufacturing.
20 of 20 listing vendors publish an accessible certificate policy
Whether the vendors carrying this compound publish per-lot certificates anyone can read without an account.
11 of 11 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.