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Thymosin Alpha-1

Also known as: Thymalfasin, Zadaxin, Tα1

FDA Banned (Category B)

Molecular Formula

C129 H215 N33 O55

Molecular Weight

3,108.315 Da

Half-Life

~1.933 hours

Sequence

Ac-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-OH

Clinical Applications & Evidence

Mechanism of Action

Tα1 engages primarily with membrane-bound and endosomal Toll-like receptors (specifically TLR2, TLR3, TLR4, TLR7, and TLR9) on dendritic and innate immune cells. This receptor engagement initiates complex intracellular signaling cascades—including MyD88, p38MAPK, NF-κB, and IRF3—which orchestrate the production of immune-related cytokines, stimulate Th1 lineage polarization, enhance natural killer (NK) cell activity, and reduce cellular oxidative stress.

Investigated Uses

  • Chronic hepatitis B and C (approved in 30+ countries)
  • Immune reconstitution in immunocompromised patients
  • Adjunct cancer immunotherapy
  • Vaccine response enhancement
  • Chronic fatigue and post-viral syndromes
Extensive Clinical Data

Regulatory & Safety Status

FDA Status

FDA Banned (Category B)

WADA / Athletic Status

Prohibited in Competition

Known Side Effects

Injection site rednessMild fatigueRarely: rash

Contraindications

  • Organ transplant recipients on immunosuppression
  • Active autoimmune flares

Drug Interactions

  • Concomitant use with systemic immunosuppressants and corticosteroids requires careful clinical evaluation, though no significant adverse drug interactions have been definitively established in critical care settings

Citations & Clinical Trials

PubMed Thymosin alpha 1: A comprehensive review of the literature PubMed Thymosin α1 and its role in viral infectious diseases FDA Pharmacy Compounding Advisory Committee Meeting Alternative Therapies Comprehensive review of the safety and efficacy of thymosin alpha 1