Thymosin Alpha-1
Also known as: Ta1 · Zadaxin · Thymalfasin
Contents
MW
3108.29 Da
Amino Acids
28 AA
Half-Life
2 hours
Route
SubQ
CAS
62304-98-7
Formula
C129H215N33O55
Amino Acid Sequence
SDAAVDTSSEITTKDLKEKKEVVEEAEN
Mechanism of Action
Thymosin Alpha-1 (Tα1) is a 28-amino acid peptide naturally produced in the thymus gland. FDA-approved in over 35 countries as Zadaxin (thymalfasin) for hepatitis B, hepatitis C, and as a vaccine adjuvant.
PRIMARY — T-CELL MATURATION: Binds TLR7/TLR9 on dendritic cells and macrophages → innate immune signaling → differentiation of naïve T-cells into mature Th1 and CTLs. Shifts from Th2-dominant toward Th1-dominant cellular immunity.
SECONDARY — NK CELL ENHANCEMENT: Directly activates NK cells independently of T-cell pathways — effective even in T-cell-depleted states (HIV, chemotherapy).
THIRD — DENDRITIC CELL MATURATION: Drives pDC maturation → Type I interferons (IFN-α, IFN-β) — primary antiviral signaling molecules.
FOURTH — MHC CLASS I UPREGULATION: Increases MHC-I on tumor cells, making them visible to CTLs.
TLR SIGNALING: TLR7/9 → MyD88 → NF-κB and IRF7 → cytokine production (TNF-α, IL-6, IL-12, IFN-α).
COVID-19: Multiple Chinese clinical trials demonstrated reduced mortality in severe COVID-19 (11.4% vs 30.0%, p=0.032), shorter ICU stays, faster immune reconstitution.
Dosing Protocol
Low Dose
███ – ███ mcg/day
Standard Dose
███ mcg/day
High Dose
███ – ███ mcg/day
Dosing protocols are for paid members
Get exact dosing ranges, injection frequency, timing rationale, and reconstitution math.
Get Clinical Access — $79/moFrequency
Standard: twice weekly (Monday/Thursday).
Half-Life
2 hours
Reconstitution Guide
Full reconstitution protocol with BAC water volumes, concentration math, and units-to-draw per dose is available on the Clinical plan.
Unlock reconstitution guide →Clinical Warnings
Organ transplant ABSOLUTE CONTRAINDICATION — may trigger rejection.
Autoimmune caution (Th1 shift may exacerbate RA, lupus, MS).
Checkpoint inhibitor interaction — additive immune activation.
Not FDA approved in USA (approved in 35+ other countries).
Pregnancy caution.
GvHD risk post-allogeneic transplant.
Contraindications
Absolute
Organ transplant recipients on immunosuppressants
Pregnancy
Relative Cautions
Autoimmune disease
Current immunotherapy
Side Effect Profile
Mild
- ●Injection site reaction
- ●Mild fatigue
Moderate
- ●Flu-like symptoms
- ●Muscle aches
Severe (Rare)
- ●Autoimmune flare (theoretical)
- ●Graft rejection
Synergistic Peptides
Common Stacks
LL-37
Selank
Research Status
STRONG — APPROVED IN 35+ COUNTRIES. COVID-19 RCT (PMID 32425019): 11.4% vs 30.0% mortality. Hepatitis B: meta-analysis of 22 RCTs confirmed efficacy. Cancer: Phase III adjuvant trials in NSCLC, HCC, melanoma. Vaccine adjuvant Phase II/III data.
Frequently Asked Questions
How does Thymosin Alpha-1 work?
Thymosin Alpha-1 (Tα1) is a 28-amino acid peptide naturally produced in the thymus gland. FDA-approved in over 35 countries as Zadaxin (thymalfasin) for hepatitis B, hepatitis C, and as a vaccine adjuvant. PRIMARY — T-CELL MATURATION: Binds TLR7/TLR9 on dendritic cells and macrophages → innate immune signaling → differentiation of naïve T-cells into mature Th1 and CTLs. Shifts from Th2-dominant toward Th1-dominant cellular immunity. SECONDARY — NK CELL ENHANCEMENT: Directly activates NK cells
What is the standard dose of Thymosin Alpha-1?
Thymosin Alpha-1 dosing protocols are available with a ClinPep Clinical subscription. Dosing varies by indication and patient factors — consult a licensed healthcare provider. General frequency: Standard: twice weekly (Monday/Thursday).
What is the half-life of Thymosin Alpha-1?
The half-life of Thymosin Alpha-1 is 2 hours. This determines optimal dosing frequency and timing.
Who should not use Thymosin Alpha-1?
Thymosin Alpha-1 is absolutely contraindicated in: Organ transplant recipients on immunosuppressants; Pregnancy. Use with caution in: Autoimmune disease; Current immunotherapy.
What are the side effects of Thymosin Alpha-1?
Common mild side effects include: Injection site reaction, Mild fatigue. Moderate effects: Flu-like symptoms, Muscle aches.
What peptides stack well with Thymosin Alpha-1?
Thymosin Alpha-1 is commonly stacked with: LL-37, Selank, BPC-157.
How do you reconstitute Thymosin Alpha-1?
Thymosin Alpha-1 is reconstituted with bacteriostatic water. Exact volumes, concentrations, and units-to-draw calculations are available in the ClinPep Clinical plan. Always follow your compounding pharmacy's instructions.
How long should you cycle Thymosin Alpha-1?
Thymosin Alpha-1 cycle protocols vary by indication. Detailed cycle length, on/off schedules, and monitoring guidelines are available with ClinPep Clinical access. Consult your healthcare provider for personalized cycling guidance.
References & Citations
10 PubMed studies · 3 clinical trials
Aging and Thymosin Alpha-1.
Simonova Maria A, Ivanov Igor, Shoshina Natalia S, Komyakova Alina M et al.. International journal of molecular sciences. 2025
Aging is characterized by immune decline, mainly due to thymic involution-the age-related shrinkage of the thymus gland. This leads to reduced T-cell production, chronic inflammation, and increased su
Thymosin α1 Combined With 2HRZE/4HR Regimen as a Potential Treatment of Pulmonary Tuberculosis: An Analysis of Immune Function, Pulmonary Function and Inflammatory Response.
Wu Guofeng, Sun Xuelian. British journal of hospital medicine (London, England : 2005). 2025
Aims/Background Immunotherapy plays a critical role in the clinical treatment of tuberculosis, an infectious disease caused by Mycobacterium tuberculosis, in which immune damage promotes the occurrenc
Efficacy of thymosin α1 for sepsis: a systematic review and meta-analysis of randomized controlled trials.
Gu Bin, Zhou Yu, Nie Yao, Wang Luhao et al.. Frontiers in cellular and infection microbiology. 2025
Despite advances in understanding sepsis pathophysiology and extensive research, few treatments effectively target its underlying immune dysfunction. Thymosin α1 (Tα1) shows promise as an
The Immunomodulatory Activity of Thymosin Alpha 1 on Tumor Cell Lines and Distinct Immune Cell Subsets.
Solmonese Laura, Lofiego Maria Fortunata, Fazio Carolina, Marzani Francesco et al.. OncoTargets and therapy. 2025
The immune-balancing role of thymosin alpha 1 (Tα1) is well-recognized in contexts of immune dysregulation. Within the anti-tumor context, Tα1 demonstrated to act as an immune-enhancer, wi
Unveiling lymphocyte dynamics: Navigating postoperative immune landscapes in gastric cancer patients undergoing laparoscopic D2 gastrectomy.
Gao Chun, Zhu Li, Tong Yi Xin, Zhang Sheng. International journal of immunopathology and pharmacology. 2025
Patients with locally advanced gastric cancer often face postoperative complications and insufficient short-term outcomes. Understanding the changes in peripheral lymphocyte subsets following laparosc
Thymosin alpha 1 alleviates inflammation and prevents infection in patients with severe acute pancreatitis through immune regulation: a systematic review and meta-analysis.
Tian Yong, Yao Jiaqi, Ma Yihan, Zhang Pengcheng et al.. Frontiers in immunology. 2025
Immune and inflammatory disorders are part of the complex pathophysiological processes that exacerbate severe acute pancreatitis (SAP) and subsequent infection. Thymosin alpha 1 (Tα1) is an impo
The Synergistic and Attenuated Mechanism of Action of the Xihuang Pill in Dual Immunotherapy After Stenting for Advanced Cholangiocarcinoma: A Controlled Clinical Trial.
Wang Peng, Wang Yu-Huan, Tao Yun, Zheng Xiang-Long et al.. International journal of general medicine. 2025
This study aims to investigate the synergistic and attenuation mechanism of Xihuang pill in the treatment of cholangiocarcinoma (CCA), thereby providing a reliable scientific basis for the selection o
Effect of thymosin α1 on Immune response and organ function in acute aortic dissection surgery: PANDA II trial protocol.
Liu Hong, Qian Si-Chong, Zhang Ying-Yuan, Tang Cheng-Bin et al.. Future cardiology. 2025
This multicenter randomized controlled trial evaluates the efficacy of thymosin alpha 1 (Tα1) supplementation in preventing organ dysfunction following acute type A aortic dissection (ATAAD) rep
Registered Clinical Trials
Dendritic Cell Based Therapy for Breast Cancer Patients
A Trial of Thymalfasin in Adult Patients With Hepatocellular Carcinoma
Protective Effect of Thymosin Α1 Against Negative Immune Dysregulation and Organ Dysfunction After Acute Aortic Dissection Surgery (PANDA II)
Symptom Indications
Full Clinical Access
Complete Thymosin Alpha-1 Protocol
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This information is for educational and research reference purposes only. ClinPep does not provide medical advice, diagnosis, or treatment recommendations. All protocols should be reviewed by a licensed healthcare provider.