Thymosin alpha-1 and thymosin beta-4 (TB-500)

The two peptides sit at very different points on the evidence curve, and neither has longevity evidence. Thymosin alpha-1 has a real clinical trial record, but in infectious disease and oncology adjunct settings, not healthspan. The most decisive recent datapoint is negative: the TESTS trial (BMJ, 2025), a multicentre double-blind placebo-controlled phase 3 study in 1,106 adults with sepsis, found 28-day all-cause mortality of 23.4% on thymosin alpha-1 versus 24.1% on placebo (HR 0.99, 95% CI 0.77-1.27, P=0.93) and did not meet its primary endpoint. Earlier meta-analyses in sepsis and COVID-19 suggested a possible mortality benefit, but those were built on smaller, mostly single-country trials and are outweighed by the adequately powered phase 3 result. Thymosin beta-4 is weaker still: its human data come from RegeneRx's phase 2 programme in dermal wound healing and dry eye disease (topical/ophthalmic RGN-259), and no completed phase 2 or phase 3 RCT has tested systemic injectable thymosin beta-4 or TB-500 for tendon, ligament or muscle injury, which is the use most buyers are actually seeking. Regeneration and anti-ageing claims for TB-500 rest on rodent and in-vitro work plus mechanism. Two further caveats: TB-500 is a fragment and is not pharmacologically interchangeable with the full-length thymosin beta-4 used in the trials, and compounded peptide supplied outside the ARTG carries no assurance of identity, purity or dose. Thymosin beta-4 is also banned in sport at all times by WADA under the growth factors category, which matters for any athletic client.

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What is Thymosin alpha-1 and thymosin beta-4 (TB-500)?

The two peptides sit at very different points on the evidence curve, and neither has longevity evidence. Thymosin alpha-1 has a real clinical trial record, but in infectious disease and oncology adjunct settings, not healthspan. The most decisive recent datapoint is negative: the TESTS trial (BMJ, 2025), a multicentre double-blind placebo-controlled phase 3 study in 1,106 adults with sepsis, found 28-day all-cause mortality of 23.4% on thymosin alpha-1 versus 24.1% on placebo (HR 0.99, 95% CI 0.77-1.27, P=0.93) and did not meet its primary endpoint. Earlier meta-analyses in sepsis and COVID-19 suggested a possible mortality benefit, but those were built on smaller, mostly single-country trials and are outweighed by the adequately powered phase 3 result. Thymosin beta-4 is weaker still: its human data come from RegeneRx's phase 2 programme in dermal wound healing and dry eye disease (topical/ophthalmic RGN-259), and no completed phase 2 or phase 3 RCT has tested systemic injectable thymosin beta-4 or TB-500 for tendon, ligament or muscle injury, which is the use most buyers are actually seeking. Regeneration and anti-ageing claims for TB-500 rest on rodent and in-vitro work plus mechanism. Two further caveats: TB-500 is a fragment and is not pharmacologically interchangeable with the full-length thymosin beta-4 used in the trials, and compounded peptide supplied outside the ARTG carries no assurance of identity, purity or dose. Thymosin beta-4 is also banned in sport at all times by WADA under the growth factors category, which matters for any athletic client.

How strong is the evidence for Thymosin alpha-1 and thymosin beta-4 (TB-500)?

Preclinical. Evidence comes from laboratory or animal work, not from human trials.

Is Thymosin alpha-1 and thymosin beta-4 (TB-500) approved in Singapore?

Health Sciences Authority position on record: Split status, and different from the Australian picture. Thymosin alpha-1 IS registered with HSA: Zadaxin Injection is a live HSA-registered product (licence SIN07483P, subcutaneous), indicated as monotherapy or in combination with interferon for chronic hepatitis B. It is not subsidised and it is not registered for any immune-ageing, healthspan or longevity indication, so any longevity use would be off-label prescribing of a registered medicine. Thymosin beta-4 / TB-500 could not be verified as an HSA-registered product in this session and appears not to be registered; it is therefore treated as an unregistered therapeutic product, which in Singapore may only reach a patient through a doctor under HSA's unregistered-product import/supply provisions. No Singapore clinic from the supplied universe was verified as offering either peptide.. An evidence grade and a regulatory approval are different questions.

Is Thymosin alpha-1 and thymosin beta-4 (TB-500) approved in Australia?

Therapeutic Goods Administration position on record: Not on the ARTG. Neither peptide is TGA-approved or registered for any indication in Australia. Thymosin beta-4 and TB-500 are explicitly named in Schedule 4 and in Appendix D of the Poisons Standard, confirmed on the NSW Health Schedule 4 Appendix D list of prescribed restricted substances, which are prescription-only substances judged liable to abuse, misuse and diversion and subject to more stringent possession and supply controls. Possession without a lawful prescription or professional authority is an offence. Where supplied lawfully, they are prescriber-directed compounded preparations from a licensed Australian compounding pharmacy, or accessed via the TGA Special Access Scheme or Authorised Prescriber pathway. The specific scheduling entry for thymosin alpha-1 could not be verified from an authoritative TGA source and is left unstated rather than guessed; it is in any case not ARTG-registered. Australian clinics were verified offering these peptides (GL Vitality Drips lists both for consultation and prescription; Folium Health in Sydney references TB-500), but neither clinic appears in the supplied variis universe.. An evidence grade and a regulatory approval are different questions.

What else is Thymosin alpha-1 and thymosin beta-4 (TB-500) called?

Also known as thymosin, Thymosin Alpha-1, Ta1, Thymalfasin, Zadaxin, Thymosin Beta-4, Tbeta4, TB-500.