Follistatin half-life & pharmacokinetics

Reported half-life

Approximately 3-8 hours plasma half-life depending on isoform (follistatin-315 has shorter half-life than follistatin-344). Recombinant preparations have been engineered for extended half-life through Fc-fusion (ACE-083) and other modifications. Local intramuscular injection produces prolonged tissue residence beyond systemic pharmacokinetics.

The half-life and pharmacokinetic profile of Follistatin reported above is drawn from the published pre-clinical literature. Plasma half-life describes the time taken for the circulating concentration to fall by half after a single dose; tissue half-life — which may be longer for peptides retained in specific organs or matrices — is a distinct and often more relevant parameter for healing research, where the duration of exposure at the injury site matters more than the systemic exposure profile.

Routes of administration studied

• Subcutaneous injection (research)
• Intramuscular injection (research; local delivery to target muscle)
• Intravenous infusion (clinical trial contexts)

Different routes produce materially different pharmacokinetic profiles for the same peptide. Subcutaneous administration generally produces flatter, more sustained plasma profiles than intravenous bolus dosing; intraperitoneal administration (common in rodent models) is not directly translatable to human routes; oral administration faces the additional challenge of luminal and brush-border peptidase degradation, which is why most research peptides have very low oral bioavailability without protective formulation.

Drug class

Secreted glycoprotein; high-affinity antagonist of TGF-β superfamily ligands, particularly myostatin (GDF-8) and activins; skeletal-muscle-hypertrophy-promoting compound.

Mechanism context

Half-life interpretation depends on the underlying mechanism. Follistatin acts as follows:

Follistatin is a 315- or 344-amino-acid secreted glycoprotein (two principal isoforms generated by alternative splicing) originally isolated by Nakatani Ueno and colleagues from bovine ovarian follicular fluid in 1987 as a factor suppressing pituitary follicle-stimulating hormone (FSH) secretion. Subsequent characterisation established the compound as a high-affinity antagonist of TGF-β superfamily members, with particularly notable inhibition of activins (the original FSH-suppressing mechanism) and myostatin (GDF-8, the principal endogenous negative regulator of skeletal muscle mass).

See the full Follistatin research profile for the complete mechanism summary, history, study citations, and references.

Practical considerations

Short plasma half-life does not necessarily mean short duration of biological effect. Many peptides — including BPC-157, GHK-Cu, and the thymosin-derived compounds — exhibit tissue retention or mechanistic effects (gene expression, signalling cascades) that outlast plasma exposure by hours to days. The pharmacological half-life and the biological-effect half-life are distinct parameters that must both be specified in any rigorous research design. Repeated-dose protocols should account for accumulation only where tissue half-life is genuinely long; for most peptides with short plasma half-life and rapid degradation, accumulation is not a practical concern.

For dose ranges in published research, see the dosing reference page. For reconstitution guidance, see the reconstitution reference page.