Specialized Research

Thymosin Alpha-1

Also known as: Tα1, Zadaxin, Timosina Alfa-1

Molecular Identifiers

Molecular Formula

C129H215N33O55

CAS Number

62304-98-7

PubChem CID

16130571

Molecular Weight

3108 Da

Overview

Immunomodulatory peptide of 28 amino acids originally isolated from the thymus. Activates dendritic cells, promotes T lymphocyte maturation and enhances the adaptive immune response. Approved in several countries for hepatitis B and C.

The main clinical interest around Thymosin Alpha-1 is its immunomodulatory role: it activates dendritic cells, promotes T lymphocyte maturation, increases NK cell activity, and modulates cytokines such as IL-2 and interferons. Additional research lines explore its adjuvant use in vaccines, in cancer patients, and in states of immunosuppression associated with chronic infections or immune senescence.

It is the only thymic peptide with broad regulatory approval for clinical use. Marketed as Zadaxin in more than 30 countries, it is mainly indicated for chronic hepatitis B and C, generally in 6 to 12 month protocols, with subcutaneous administration twice a week. Outside these indications, it is prescribed off-label in shorter cycles for general immunomodulation, with a safety profile considered excellent after decades of clinical use.

Despite the shared name, Thymosin Alpha-1 should not be confused with TB-500 (Thymosin Beta-4): they are distinct proteins with different sequences, structures, and functions. TB-500 is a fragment of thymosin β-4, acting on tissue repair via G-actin sequestration and cell migration, whereas Thymosin Alpha-1 is a 28-amino acid chain with an immunomodulatory role and no regenerative indication. The naming overlap is historical — both were originally isolated from thymic extracts — but their clinical use is entirely separate.

Sequence (1 letter): SDAAVDTSSEITTKDLKEKKEVVEEAEN
Extended notation: Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn

Half-life

~2 hours

Administration Route

Subcutaneous

Category

Specialized Research

Mechanism of Action

  • Dendritic cell activation and antigen presentation
  • Promotion of T lymphocyte maturation and differentiation
  • Increased NK (natural killer) cell activity
  • Cytokine modulation (IL-2, IFN-α, IFN-γ)
  • Enhancement of vaccine response

Dosage Protocol

Data compiled from the literature. This does not constitute medical advice.

Parameter Value
Dose 1.6 mg per injection
Frequency Twice per week
Timing Any time of day
Duration 6-12 months (hepatitis) or 2-4 week cycles (immunomodulation)

Reported Side Effects

Adverse effects described in the literature. Severity and frequency vary between individuals.

  • Injection site pain
  • Erythema
  • Mild fatigue
  • Low-grade fever (rare)

Product Properties

Purity >99%
Appearance White lyophilized powder
Solubility Soluble in water and bacteriostatic water
Source Solid-phase peptide synthesis (SPPS)
Storage Lyophilized: -20°C for up to 2 years, 2-8°C for up to 6 months. Reconstituted: 2-8°C for up to 4 weeks. Protect from light and moisture. Avoid repeated freeze-thaw cycles.

Presentations & Preparation

Vials of Thymosin Alpha-1 found in the research market:

1.6 mg3 mg10 mg

Reconstitution

  • Diluent: Bacteriostatic water or water for injection
  • Volume: 1 ml per 1.6 mg vial
  • Slowly inject diluent
  • Gently swirl without shaking
  • Use immediately after reconstitution

Storage

  • Lyophilized: Refrigerated 2-8°C
  • Reconstituted: Refrigerated 2-8°C (use within 24 hours)
  • Do not freeze
  • Protect from light
Reconstitution Calculator

Scientific Studies

Published studies on Thymosin Alpha-1.

2013 · Critical Care

The efficacy of thymosin alpha 1 for severe sepsis (ETASS) - a multicenter, single-blind, randomized and controlled trial

Wu J, Zhou L, Liu J, Ma G, Kou Q, He Z, Chen J, Ou-Yang B, Chen M, Li Y, Wu X, Gu B, Chen L, Zou Z, Qiang X, Chen Y, Lin A, Zhang G, Guan X
1998 · Hepatology

Efficacy of thymosin alpha1 in patients with chronic hepatitis B - a randomized, controlled trial

Chien RN, Liaw YF, Chen TC, Yeh CT, Sheen IS

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