Contents: Thymosin α₁ (thymalfasin).

Description: Each vial also contains the following excipients: Mannitol 50 mg and sodium phosphate buffer to adjust the pH to 6.8. The diluent used is sterile water for injection.
Zadaxin for SC injection is a purified, sterile, lyophilized preparation of chemically synthesized thymosin α₁.
Thymosin α₁ is an acetylated polypeptide with the following sequence: Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH. It has a molecular weight of 3108 daltons and a pl of 3.8.
Thymosin α₁ is also known as thymalfasin.