Both are short peptides with claimed immune or longevity effects, and they differ enormously in how independently they have been studied. Thymosin alpha-1 is approved in a number of countries. Epithalon's evidence comes from essentially one research group.
Side by side
| Epithalon | Thymosin Alpha-1 | |
|---|---|---|
| Class | Pineal tetrapeptide | Immunomodulatory peptide |
| Status | Research compound | Approved in 35+ countries (Zadaxin); not FDA approved; barred from US 503A compounding |
| Route | Subcutaneous injection | Subcutaneous injection |
| Typical vials | 10 mg, 20 mg, 50 mg | 5 mg, 10 mg |
| Dose range | 5 mg to 10 mg | 0.8 mg to 3.2 mg |
| Frequency | Daily, in courses | Twice weekly |
| Half-life | No human data | ~2 hours |
| Dosing unit | milligrams | milligrams |
Pharmacokinetics
No curves are shown, on purpose.
No published human pharmacokinetics for Epithalon. Drawing one curve against an absent one would imply a comparison that cannot be made.
What the evidence supports
These grade how well each outcome has been studied in humans, never how well either compound works. A strong grade can sit on a negative result.
The strongest evidence for any claimed outcome is Human RCT for Thymosin Alpha-1 and Human, observational for Epithalon. That gap is the most important line on this page.
Epithalon
| Outcome | Evidence |
|---|---|
| Human aging markers and mortality | Human, observational |
| Lifespan in rodents | Animal only |
| Telomerase activity in cell culture | Mechanistic only |
| Independent replication of any result | No data |
Thymosin Alpha-1
| Outcome | Evidence |
|---|---|
| Chronic hepatitis B | Human RCT |
| Immune modulation markers | Human RCT |
| Sepsis outcomes | Human RCT |
| COVID-19 outcomes | Human, observational |
How to choose
Thymosin alpha-1 has independent clinical use
Approved in several countries for hepatitis B and C and as an immune adjuvant, though not by the FDA.
Epithalon has never been independently replicated
Decades of work from one Russian group, and no confirmation from anyone else. That is the single most important fact about it.
Telomerase induction is a cell-culture finding
It is the basis of the longevity claim and has not been connected to any human outcome.
At the syringe
At the default setup on each compound's own page, a 10 mg vial in 2 mL puts 50 mcg on every insulin unit, while a 5 mg vial in 2 mL puts 25 mcg on every unit. That is the number that decides whether a dose lands on a readable mark, and it is set by how much water goes in, not by the compound.