Thymosin Alpha-1: research protocol, dosing & reconstitution
Also known as: Tα1, Thymalfasin, Zadaxin
Quick answer
What is Thymosin Alpha-1?
Thymosin alpha-1 is a 28-amino-acid peptide first isolated from the thymus, the organ that trains T cells. It is studied as an immune regulator — it nudges dendritic cells and T cells toward a balanced response rather than switching immunity ‘up’ — and is an approved prescription drug (thymalfasin) in more than 30 countries, though not in Canada or the US.
What Thymosin Alpha-1 is
Thymosin α1 (Tα1) was isolated in 1977 by Allan Goldstein's group from thymosin fraction 5, a crude thymus extract, and was later found to be produced throughout the body as a fragment of prothymosin α [1]. Unlike most research peptides it has a long clinical history: as an adjunct in chronic hepatitis B and C, as a vaccine adjuvant, and in immune-deficient states, under the brand name Zadaxin.
That approval history matters for how it is discussed. There is real dose-ranging and safety data in humans — but all of it comes from pharmaceutical-grade thymalfasin given to patients, not from research-grade material, which in Canada is sold strictly as a Research Use OnlyRUO (Research Use Only)A regulatory classification meaning a product is sold strictly for laboratory research and is not approved, labeled, or intended for human or veterinary use.See glossary → compound.
Mechanism of action
Tα1 acts on innate immunity first. It activates dendritic cells through Toll-like receptorReceptorA protein on or inside a cell that binds specific signaling molecules and triggers a response. Most peptides work by binding particular receptors.See glossary → signalling and switches on tryptophan catabolism (indoleamine 2,3-dioxygenase), establishing a regulatory environment that balances inflammation against tolerance rather than simply amplifying either [2].
Downstream, it promotes T-cell maturation and NK-cell activity, improves antigen presentation, and increases the response to vaccines and viral infection — the basis of its use alongside antivirals in hepatitis B. A meta-analysis of eight trials (583 patients) found lamivudine plus Tα1 beat lamivudine alone on ALT normalisation, virological response, and HBeAg seroconversion (45% versus 15%) [4].
A 2020 review collects the wider literature — sepsis, immunosenescence in older adults, cancer adjunct therapy, and COVID-19 — and the consistent finding of a very benign safety profile across decades of clinical use [3].
What researchers study Thymosin Alpha-1 for
- Dendritic-cell activation and Toll-like receptor signalling
- Antiviral adjunct therapy (hepatitis B and C models)
- Vaccine-response enhancement and immunosenescence
- Sepsis and immune-paralysis models
What dose of Thymosin Alpha-1 do researchers use?
Research literature commonly references doses of 1.6 mg twice weekly (approved regimen abroad); community protocols reference 300–500 mcg daily. This is not a recommendation — the table below summarizes protocols as they appear in published literature and trial designs.
| Context | Dose | Frequency | Duration |
|---|---|---|---|
| Approved regimen abroad — chronic hepatitis B [3][4] | 1.6 mg SC | Twice weekly | 6–12 months |
| Vaccine-adjuvant studies [3] | 1.6 mg SC | Twice weekly around vaccination | Short course (weeks) |
| Community research reference | 300–500 mcg SC | Once daily | 8–12 weeks referenced; not a trial regimen |
← Swipe to see the full table
Half-life and dosing timing
Half-life: ~2 hours. Route referenced in research: Subcutaneous (research). Plasma half-lifeHalf-lifeHow long it takes for half of a compound to be eliminated from the body. Half-life determines how often researchers dose a compound in protocols.See glossary → is about two hours, yet the approved regimen is only twice weekly — because the effect is on immune-cell programming, which persists long after the peptide is gone. Daily community protocols are not more ‘potent’; they simply spread a similar weekly total across more injections.
Titration: start low, go slow
Clinical use does not titrateTitrationStarting at a low dose and increasing gradually on a schedule. Research protocols titrate to assess tolerance — 'start low, go slow.'See glossary →: patients start and stay at 1.6 mg twice weekly. Community protocols sometimes open at 300 mcgMicrogram (mcg / µg)One millionth of a gram, or one thousandth of a milligram. Most peptide research doses are measured in micrograms.See glossary → daily for a week before 500 mcg; that is convention rather than published guidance.
Skip the Thymosin Alpha-1 math
Enter vial size, water volume, and target dose — the free calculator returns concentration, injection volume, and exact U-100 syringe units.
How is Thymosin Alpha-1 reconstituted?
| Vial size | BAC water | Concentration | Worked example |
|---|---|---|---|
| 10 mg | 2 mL | 5,000 mcg/mL | 1.6 mg = 0.32 mL = 32 units on a U-100 syringe |
| 5 mg | 2 mL | 2,500 mcg/mL | 500 mcg = 0.2 mL = 20 units on a U-100 syringe |
Add 2 mL of bacteriostatic waterBAC water (bacteriostatic water)Sterile water containing 0.9% benzyl alcohol, which suppresses bacterial growth. It is the standard diluent used to reconstitute lyophilized peptides for multi-dose research vials.See glossary → to a 10 mg vialVialThe small sealed glass container peptides are supplied in, topped with a rubber septum that a syringe needle can pass through.See glossary →: 10 mg ÷ 2 mL = 5 mg/mL, or 5,000 mcg/mL. The clinical 1.6 mg dose is 1,600 ÷ 5,000 = 0.32 mL — 32 units on a U-100 syringeU-100 syringeAn insulin syringe calibrated so that 100 units equal 1 mL. The standard syringe referenced in peptide research; each unit equals 0.01 mL.See glossary →. A 500 mcg dose from the same vial is 0.1 mL, or 10 units.
New to the process? Read the full step-by-step reconstitution guide.
How long does reconstituted Thymosin Alpha-1 last?
LyophilizedLyophilizedFreeze-dried. Peptides are shipped as a lyophilized powder ('puck') because the dry form is far more stable than a solution. It must be reconstituted before use in research.See glossary →: refrigerated, stable roughly 12–24 months. ReconstitutedReconstitutionThe process of mixing a freeze-dried (lyophilized) peptide powder with bacteriostatic water to create a solution of known concentration.See glossary →: 2–8°C and used within a few weeks. Research-grade material has none of the pharmaceutical product's stability testing behind it, so treat it as fragile.
What is Thymosin Alpha-1 stacked with in research?
Not usually stackedPeptide stackTwo or more peptides used together in a research protocol because their mechanisms are complementary — for example, BPC-157 with TB-500.See glossary →. It is discussed alongside BPC-157 and KPV in inflammation-focused protocols, and with thymosin beta-4 (the parent of TB-500) — a different peptide from the same tissue with a different job: cell migration rather than immune regulation.
Side effects observed in research
Decades of clinical use report injection-site redness and occasional transient fatigue, and little else; the 2020 review describes it as one of the best-tolerated immunomodulators in the literature [3]. Research-grade material has none of that pharmaceutical quality assurance behind it, which is why it is sold as Research Use Only.
- Injection-site redness or irritation
- Transient fatigue
- Generally well tolerated across decades of clinical use
Source in Canada
COA-documented research compounds, sourced from Canada.
RegenBioSignals →Referral partner — we may earn a commission.
Frequently asked questions
Is thymosin alpha-1 approved in Canada?
No. Thymalfasin (Zadaxin) is approved in more than 30 countries, mostly in Asia and southern Europe, as an adjunct in hepatitis B and for immune support [3]. It has no approval from Health Canada or the FDA, so any product sold here is Research Use Only.
What dose do clinical trials use?
1.6 mg subcutaneously twice weekly is the near-universal clinical regimen, from hepatitis B trials through vaccine-adjuvant studies [3][4]. The daily 300–500 mcg schedules seen online are community protocols with no trial behind them.
Does it ‘boost’ the immune system?
The literature describes regulation rather than boosting: it activates dendritic cells and at the same time switches on tolerance pathways such as tryptophan catabolism [2]. That is why it is studied in both under-active states (immunosenescence) and over-active ones (sepsis).
How is it different from TB-500?
Both were named after the thymus, and that is where the similarity ends. TB-500 is a fragment of thymosin beta-4, studied for cell migration and tissue repair; thymosin alpha-1 is a separate peptide studied for immune regulation.
Related research peptides
Glutathione
The body's main antioxidant — a three-amino-acid molecule made inside every cell — studied for oxidative stress, immune function and, more controversially, skin lightening.
Immune / GutVIP
A 28-amino-acid signalling peptide found in the gut, lungs, brain and immune system, studied for immune regulation and for relaxing airways and blood vessels. Survives about a minute in blood, so research uses inhaled or intranasal routes.
Healing & RecoveryBPC-157
A synthetic peptide fragment studied for tissue repair, tendon/ligament and gut healing in animal research.
Browse all Immune / Gut peptides or start with the beginner’s guide to research peptides.
References
- 1.Garaci E. Thymosin alpha1: a historical overview. Ann N Y Acad Sci. 2007. PubMed ↗
- 2.Romani L, et al. Thymosin alpha1 activates dendritic cell tryptophan catabolism and establishes a regulatory environment for balance of inflammation and tolerance. Blood. 2006. PubMed ↗
- 3.Dominari A, et al. Thymosin alpha 1: A comprehensive review of the literature. World J Virol. 2020. PubMed ↗
- 4.Zhang YY, et al. Treatment with lamivudine versus lamivudine and thymosin alpha-1 for e antigen-positive chronic hepatitis B patients: a meta-analysis. Virol J. 2009. PubMed ↗