Is thymosin alpha 1 the same as TB-500?
No. They are different molecules that come from different parent peptides. Thymosin alpha-1 (thymalfasin, Zadaxin) is an immune-adjusting peptide from the thymus, with a molecular weight of 3,108 daltons. Its record includes the 1,106-person TESTS sepsis study and a 98-person hepatitis B study. TB-500 is a piece of thymosin beta-4 (building blocks 17 to 23, with an acetyl group on the front), with the chain Ac-LKKTETQ and a molecular weight of 889.01 daltons in its plain form. The FDA's 2026 review found no published study giving TB-500 to a person. Sharing the word thymosin does not mean they share a molecule or an evidence record. This site does not rank them. Full records at /compounds/thymosin-alpha-1 and /compounds/tb-500.
Studies in people from the compound pages this answer belongs to
- Thymosin Alpha-1
- Efficacy of thymosin alpha1 in patients with chronic hepatitis B: a randomized, controlled trial 1998 PMID 9581695
- The efficacy and safety of thymosin alpha 1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial 2025 PMID 39814420
- The efficacy of thymosin alpha 1 for severe sepsis (ETASS): a multicenter, single-blind, randomized and controlled trial 2013 PMID 23327199
Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.
Part of immune and longevity peptides. Thymosin alpha-1, thymalin, epitalon, MOTS-c, humanin, and the bioregulator family.