Thymalfasin (Thymosin alpha-1)
A 28-amino-acid immunomodulatory peptide derived from thymic tissue. Marketed in several countries (as Zadaxin) for chronic hepatitis B and C and as an immune adjuvant, and studied in sepsis and as a vaccine enhancer, though it is not FDA-approved in the US.
01 Overview
Thymalfasin, the synthetic form of thymosin alpha-1, enhances T-cell maturation and function and modulates innate immune signalling. It is licensed in numerous countries outside the US for chronic viral hepatitis and as an adjunct in immunocompromised states, and has been trialled in sepsis and to boost vaccine responses.
The evidence base is moderate and geographically uneven: several controlled trials support hepatitis and immune-adjuvant uses, but results are not uniformly strong and it lacks US approval. It is also sold in the wellness/peptide market for general 'immune support', a use far less substantiated than its licensed indications.
02 Mechanism
Modulates T-lymphocyte differentiation and function and toll-like-receptor signalling, augmenting cell-mediated and innate immune responses.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Chronic hepatitis (licensed abroad) | 1.6 mg | SubQ | 1.6 mg twice weekly is the common licensed regimen. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Enhanced antiviral immune responseAugments T-cell responses, supporting its licensed hepatitis B/C use in several countries. | Improved response in some hepatitis trials | Clinical | |
| Immune adjuvant effectMay improve vaccine and immune responses in immunocompromised patients, though data are mixed. | Variable | Observational |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Injection-site reactionsLocal redness or discomfort at the injection site. | Mild | Common | Clinical | |
| Uncertain benefit in wellness useGeneral 'immune-boosting' use lacks robust evidence and product quality varies. | Mild | Unknown | Unconfirmed |