Thymosin Alpha-1
Also sold as TA1, Zadaxin, Tα1.
- Half-life
- 2 h
- Steady state
- ~0 d
- Class
- Immune
- Category
- Peptide
Published population averages. Steady state is the usual five half-life rule of thumb, not a measurement. See peptide half-life, explained.
Overview
Thymosin Alpha-1 (Tα1) is a 28-amino acid peptide naturally produced by the thymus gland. It is the primary thymic peptide responsible for T-cell maturation and immune system regulation. Synthetic Tα1 (thymalfasin, brand: Zadaxin) is approved in over 35 countries for hepatitis B/C and as an immune adjunct. Thymic output and Tα1 levels decline significantly with age, contributing to immunosenescence.
How it works
Activates toll-like receptors (TLR2, TLR9) on dendritic cells and monocytes, enhancing antigen presentation. Promotes T-cell differentiation from bone marrow progenitors, increases CD4+/CD8+ T-cell populations, enhances NK cell activity, stimulates IL-2 and IFN-α production, and reduces inflammatory cytokines (IL-6, TNF-α). Acts as an immune system 'reset' rather than simple stimulation.
Half-life and peak
Plasma half-life approximately 2 hours after subcutaneous injection. Peak concentration reached in 1–2 hours. Immunomodulatory effects persist 48–72 hours beyond plasma clearance due to downstream cascade activation. Typically dosed 1.6 mg subcutaneously, 2–3 times per week.
What it is studied for
Immune restoration in aging, hepatitis B and C, cancer immunotherapy adjunct, sepsis, vaccine response enhancement, HIV/AIDS, COVID-19 (studied during pandemic).
Research status
Approved in 35+ countries (Zadaxin). Not FDA-approved in the US (SciClone Pharmaceuticals NDA was withdrawn). Extensive clinical data from Asia and Europe. Used off-label in integrative medicine. Phase 3 data exists for Hepatitis B.
Sources
- Thymosin Alpha-1 clinical overview — Annals NY Acad Sci · doi.org
- Tα1 in COVID-19 — International Immunopharmacology · pubmed.ncbi.nlm.nih.gov
- Thymosin Alpha-1 mechanism review · doi.org
- Thymalfasin pharmacokinetics — BioDrugs · doi.org
Educational reference only. This page describes what is published about a compound; it is not medical advice, not a recommendation to take anything, and not a dosing guide. Several compounds in this catalog are investigational and are not approved medicines. Talk to a doctor.