What thymosin alpha-1 is
Thymosin alpha-1 is a peptide of 28 amino acids. FDA's review gives the formula C129H215N33O55 and a molecular weight of 3,108.3 g/mol, and lists Ta1, thymalfasin and Zadaxin among the names it goes by. The free base is a white to off-white lyophilized powder.
Where it stands with the FDA
Thymosin alpha-1 isn't approved by the FDA, and the agency says it isn't a component of any FDA-approved drug. It was nominated for compounding, the nomination was withdrawn, and FDA reviewed it on its own initiative.
The review covered a long list of uses, among them hepatitis B, hepatitis C, HIV, liver cancer, non-small cell lung cancer and sepsis. It concluded that the criteria weigh against putting thymosin alpha-1 on the list of substances pharmacies may compound with.
On December 4, 2024, FDA's Pharmacy Compounding Advisory Committee voted on it. For both the free base and the acetate the vote was 4 in favor and 17 against. The minutes say the majority voted no for lack of convincing evidence that it works.
The strength in the record
The product described in the nomination was a 3 mg/mL injection under the skin. FDA's review adds that the free base dissolves poorly in water, and that it's unclear how a 3 mg/mL injection could be made from it.
| Strength in the record | Water for a 5 mg vial | One unit holds | 10 units hold |
|---|---|---|---|
| 3,000 mcg/mL | 1.667 mL | 30 mcg | 300 mcg |
Add that much water to a 5 mg vial and it comes to that strength. Any other amount of water works too. It only changes how many units the same dose takes up.
Storing thymosin alpha-1
FDA's review says the free base is expected to be stable stored below -18°C, and repeats a report that the lyophilized powder is stable at room temperature for three weeks. Both describe the dry powder, not a mixed vial.
There's no approved label for thymosin alpha-1, so nothing official says how long a mixed vial keeps.
Thymosin Alpha-1 dosage calculator questions
How do I turn a thymosin alpha-1 dose into syringe units?
Divide the dose by the concentration to get millilitres, then multiply by 100. A 5 mg vial mixed with 2 mL is 2.5 mg/mL, so one unit on an insulin syringe holds 25 mcg and ten units hold 250 mcg.
How much bacteriostatic water goes in a 5 mg vial of thymosin alpha-1?
There's no single right amount. The water only sets the concentration, and the amount of thymosin alpha-1 in the vial stays the same. With 5 mg, 1 mL makes 5 mg/mL, 2 mL makes 2.5 mg/mL and 3 mL makes 1.667 mg/mL. Choose the amount that puts your dose somewhere between about 10 and 40 units, where it's easiest to read.
Is thymosin alpha-1 approved by the FDA?
No. FDA says thymosin alpha-1 isn't a component of any FDA-approved drug. Its advisory committee voted 4 to 17 against allowing it in compounded drugs on December 4, 2024.
Does this page tell me how much thymosin alpha-1 to take?
No. There's no FDA-approved thymosin alpha-1 product, so there's no approved dose to point to. The dose box starts empty for that reason, and the chart only converts.
More peptide calculators by name
The same instrument, set up one peptide at a time. For any other vial, use the peptide reconstitution calculator.