What is the difference between Splenin and Thymosin Alpha-1?

Splenin: Spleen-derived tetrapeptide bioregulator; normalizes leukocyte and platelet production; modulates splenic immune cell activity Thymosin Alpha-1: Tα1 modulates both innate and adaptive immune responses by stimulating the differentiation and maturation of T-cells, dendritic cells, and natural killer cells.

Is Splenin FDA approved?

Splenin is not evaluated or approved by the FDA. It is discussed for research and educational purposes only, not as medical guidance.

How is Splenin administered in research settings?

In research settings, Splenin is typically administered via the subcutaneous or intramuscular routes. PeptideBase does not provide dosing or administration instructions.

How is Thymosin Alpha-1 administered in research settings?

In research settings, Thymosin Alpha-1 is typically administered via the subcutaneous route. PeptideBase does not provide dosing or administration instructions.

Home›Research›Compare›Splenin vs Thymosin Alpha-1

Peptide Comparison

Splenin vs Thymosin Alpha-1

Name: Splenin vs Thymosin Alpha-1 — Per-mg Price Comparison
Creator: PeptideBase
License: https://peptidebase.io/terms

Both are Immune & Thymic peptides.

Splenin

Spleen peptide bioregulator

RecoveryNot EvaluatedResearch Only

Half-life: Unknown

1 providers listed

Full Splenin profile →

Thymosin Alpha-1

Thymosin Alpha

RecoveryResearch Only

Half-life: 2 hours

215 providers listed

Full Thymosin Alpha-1 profile →

Bottom line

Thymosin Alpha-1 carries stronger published evidence (RCT, 2 key studies) than Splenin (Review, 2); both are research compounds.

Quick Verdict

Splenin

Half-life

Unknown

Thymosin Alpha-1

Half-life

2 hours

Which One Should You Choose?

Your goal	Better option
Stronger clinical evidence	Thymosin Alpha-1
More provider options (1 vs 215)	Thymosin Alpha-1

Research summary only — not medical advice. Consult a qualified provider before making any decisions.

Side-by-Side Comparison

Splenin

Thymosin Alpha-1

Mechanism Family

Immune & Thymic

Half-life

Unknown

2 hours

FDA Status

not evaluated

nomination withdrawn

Admin Routes

subcutaneous, intramuscular

subcutaneous

Availability

Research Only

Providers

1 listed

215 listed

Avail. Notes

Russian peptide bioregulator from spleen (Khavinson Institute). Immunomodulatory. No FDA approval, no NDA or IND. Not on any FDA list. Research chemical in US only.

Approved as Zadaxin in China, Italy, and other countries but NOT FDA-approved. Not on FDA 503A Category 1 bulks list. Research use only in US. Immunomodulatory thymic peptide.

Research Evidence

Splenin

Review · 2 key studies · most recent 2022

Thymosin Alpha-1

RCT · 2 key studies · most recent 2026

Research Citations

Splenin

Review2022 · International Journal of Molecular Sciences

Neuroepigenetic Mechanisms of Action of Ultrashort Peptides in Alzheimer's Disease

Review2020 · Stem Cell Reviews and Reports

Peptide Regulation of Cell Differentiation

Thymosin Alpha-1

RCT2018 · Expert Opinion on Biological Therapy

Combination of entecavir with thymosin alpha-1 in HBV-related compensated cirrhosis: a prospective multicente…

Animal2026 · J Gastroenterol Hepatol

IL-15 Plus Thymosin α1 Reduces Senescent Hepatic CD8(+) T Cells in Hepatocellular Carcinoma via PI3K/AKT Supp…

About Splenin

Spleen-derived tetrapeptide bioregulator; normalizes leukocyte and platelet production; modulates splenic immune cell activity

Research Areas

immune restorationblood cell productionsplenic function support

About Thymosin Alpha-1

Tα1 modulates both innate and adaptive immune responses by stimulating the differentiation and maturation of T-cells, dendritic cells, and natural killer cells. It upregulates MHC class I and II expression, enhancing antigen presentation. It also promotes the production of key cytokines including interferon-γ and interleukin-2, which are central to immune surveillance.

Research Areas

TH1 immune activation via Toll-like receptor upregulationhepatitis B and C treatment adjuvant — approved in 35+ countriesdendritic cell maturation and antigen-specific T-cell potentiationCOVID-19 immune support research (2020–2021 Chinese clinical data)

Safety Profile

Information below reflects published research data only — not medical advice. Consult a qualified provider before use.

Splenin

No established clinical contraindications. This is an investigational compound with limited human data and has not been evaluated by the FDA for safety in this context. Consult a qualified clinician.

Thymosin Alpha-1

Absolute Contraindications

Under clinical review

Being verified by our medical team before we display contraindications for this peptide.

Price (per mg)

Splenin

Not enough vendor pricing yet.

Thymosin Alpha-1

$7.71/mg

$6.50 – $9.20 range

41 vendors

View price index →Find providers →

Find Providers

Where to source these peptides

Providers offering

Splenin

1 listed

Browse directory →

Providers offering

Thymosin Alpha-1

215 listed

Browse directory →

PeptideBase lists providers for educational research purposes only. Always consult a qualified healthcare professional before obtaining or using any peptide.

More Immune & Thymic Comparisons

Browse all peptides →

Educational research tools — not medical advice.

Cite this page

Data last updated August 26, 2026

Free to reference and republish with attribution to PeptideBase. Choose a format:

PeptideBase. (2026). Splenin vs Thymosin Alpha-1 — Per-mg Price Comparison. Retrieved September 11, 2026, from https://peptidebase.io/peptides/compare/splenin/thymosin-alpha-1

https://peptidebase.io/peptides/compare/splenin/thymosin-alpha-1 Methodology License Download JSON Download CSV