Thymosin Alpha-1
aka Tα1 · Zadaxin
An immunomodulating thymic peptide approved in more than 30 countries for hepatitis B/C and used as an adjuvant in sepsis and oncology settings, though not FDA-approved.
Mechanism of action
Signals through Toll-like receptor 9 on dendritic cells, promoting Th1 differentiation, restoring T-cell counts in lymphopenia, and enhancing NK-cell cytotoxicity.
Doses used in published studies
1.6 mg subcutaneously twice weekly in hepatitis trials; sepsis trials used 1.6 mg every 12 hours initially.
These figures describe what researchers administered under supervision. They are reported for accuracy and are not a protocol, recommendation, or substitute for clinical guidance.
Reported benefits
- Reduced 28-day mortality signal in a Chinese sepsis RCT
- Improved response rates alongside antivirals in chronic hepatitis B
- T-cell count restoration in lymphopenic patients
Risks & unknowns
- Injection-site reactions
- Theoretical autoimmune flare risk
- Heterogeneous trial quality across regions
Legal & regulatory status
Approved in China, Italy, and dozens of other markets; FDA orphan-drug designations only. Added to the FDA 503A Category 2 bulk list in 2023, restricting US compounding.
Check status in your state or country →Key studies
- Thymosin Alpha 1 in Severe Sepsis: A Randomized Controlled Trial (ETASS)
Critical Care · 2013