Thymosin Alpha-1

Immune

Also known as thymalfasin, Zadaxin, Ta1

A 28-amino-acid thymic peptide. Approved in around 35 countries, though not the US.

How it works

Immunomodulator cleaved from prothymosin alpha. Promotes T-cell maturation and raises peripheral CD4+ and CD8+ counts, while also damping excessive immune activation.

Subcutaneous

In the body

Half-life

2 hours

Time to peak

1 h

90% gone after

6.6 h

Builds up to

1×

Steady state after about 10.1 h at twice weekly.

Shape of a single dose, modelled as one compartment with first-order absorption. The peak is normalised to 100% because bioavailability and volume of distribution are not published for most of these compounds.

Described in the literature as short. The 2-hour figure is commonly cited but was not verified against a primary source. The existence of PEGylated versions confirms the short half-life is a real development problem.

Doses

1.6 mgtwice weeklyApproved label

1.6 mg subcutaneously twice weekly is the canonical maintenance regimen across hepatitis B and C trials.

1.6 mg, 3.2 mgonce or twice dailyClinical trial

Front-loaded daily dosing used in acute settings such as sepsis and acute-on-chronic liver failure.

Vial sizes

1.6 mg5 mg10 mg

Side effects

Consistently favourable across large trials. Grade 3 or worse treatment-related events in about 4% when combined with checkpoint inhibitors.

Cautions

No established contraindications from the approved labels were retrieved.

Status

Approved in around 35 countries for chronic hepatitis B and C and as a vaccine adjuvant. Not FDA approved. Not named on the WADA list.

Sources

Reference information for personal record-keeping. Not medical advice, and not a recommendation to use any of these compounds.