Thymosin Alpha-1 is an immune-modulating peptide that, under the brand name Zadaxin (thymalfasin), holds regulatory approval in roughly 35 countries for hepatitis B/C and certain cancers, though it is not broadly FDA-approved in the United States.
Not FDA-approved in the US, despite approval in 35+ other countries
Thymosin Alpha-1 (Thymalfasin, brand name Zadaxin) is approved in more than 35 countries — including China and Italy — primarily for chronic hepatitis B, but has never been FDA-approved in the United States for any indication, despite the FDA granting orphan-drug status for several indications (malignant melanoma, chronic hepatitis B, DiGeorge anomaly, hepatocellular carcinoma). This is a real, well-documented, extensively human-trialed compound — the accuracy point is specifically about US regulatory status, not about whether real trial evidence exists.
Benefits
Studied in over 20 human clinical trials at varying evidence levels, with a 2024 narrative review covering 11,000+ patients across 30+ trials. Meta-analysis, chronic hepatitis B (lamivudine + thymosin alpha-1 vs. lamivudine alone): the combination significantly outperformed lamivudine alone on ALT normalization (80.2% vs. 68.8%), virological response (84.7% vs. 74.9%), and HBeAg seroconversion (45.1% vs. 15.2%). Also studied for hepatitis C, certain cancers (melanoma, hepatocellular, lung), and as a vaccine-response enhancer.
Is Thymosin Alpha-1 FDA-approved?+
The branded form, Zadaxin, is approved in around 35 countries for hepatitis B/C and specific cancers, but it does not hold broad FDA approval in the United States, where it sits under regulatory review as a compounding substance.
What is Thymosin Alpha-1 researched for?+
Immune modulation, particularly enhancing T-cell response, studied across infections, vaccine response, and certain cancers.
Is Thymosin Alpha-1 the same as Thymulin?+
No, both are thymus-related immune peptides, but they are structurally distinct with different research histories.
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