Comparison
Follistatin (FST) vs. Hexarelin
Two peptides side-by-side — identity, evidence base, legal status and known adverse events.
Identity
Category
Growth
Growth
CAS no.
122956-17-2
140703-51-1
Molecular weight
35000 g/mol
887.05 g/mol
Half-life
no data
0.9 h
Sequence
Glykoprotein, ~315 Aminosäuren in der zirkulierenden Hauptform (Sequenz isoformabhängig, kein einheitliches kurzes Peptid)His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2Mechanism of action
Follistatin (FST)
Follistatin binds with high affinity to activin and to myostatin (GDF-8), as well as related TGF-β ligands such as GDF-11 and some BMPs, preventing their binding to the activin type-II receptors. Myostatin is a negative regulator of skeletal muscle mass; by sequestering myostatin, its growth-inhibiting signalling is removed (de-repression). Because follistatin additionally neutralises activin, it acts on several muscle-inhibiting pathways at once — in animal models this produced greater muscle gain than knocking out myostatin alone. Several isoforms exist (including FST-288 and FST-315) that differ in tissue binding via heparan sulfate. The FST344 variant used in gene therapy was chosen to reduce binding to off-target structures.
Hexarelin
Hexarelin is a synthetic analog of the GHRP-6 family binding both the GH secretagogue receptor (GHSR-1a) and CD36. GHSR activation in the pituitary releases pulsatile growth hormone. Via CD36 in endothelium and myocardium, cardioprotective effects have been described in animal studies.
Evidence base
Highest evidence
Human trial
Human trial
Studies
4
4
of which in humans
1
3
Effects recorded
4
3
Open conflicts
1
0
Documented adverse events
1
1
Legal status
Full entries
Frequently asked questions
- What is the difference between Follistatin (FST) and Hexarelin?
- Follistatin (FST) is classified as "Growth", while Hexarelin is classified as "Growth". Follistatin (FST): Follistatin is an endogenous glycosylated binding protein (~35 kDa, considerably larger than typical peptides) that binds and neutralises members of the TGF-β superfamily, including activin and myostatin (GDF-8). In animal models, raising follistatin de-represses muscle growth. Clinically it has been studied mainly via AAV gene therapy (FS344) in muscular dystrophies. Follistatin is not an approved drug; human efficacy and safety data are limited and stem mostly from early gene-therapy trials and preclinical research. A 'follistatin-344' product is sold on the grey market, the identity and purity of which cannot be verified without analytics. Hexarelin: Synthetic hexapeptide of the growth-hormone secretagogue (GHRP) family. In the 1990s investigated as an acromegaly diagnostic and for GH deficiency. Not an approved medicine. This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, Follistatin (FST) or Hexarelin?
- The highest available evidence level is "Human trial" for Follistatin (FST) and "Human trial" for Hexarelin. A higher evidence level means more robust data, but says nothing about suitability for an individual. The full body of evidence is on each peptide's own page.
- What is the legal status of Follistatin (FST) and Hexarelin in Germany and the United States?
- Germany: Follistatin (FST) — Unapproved, Hexarelin — Unapproved. United States: Follistatin (FST) — Unapproved, Hexarelin — Unapproved. These are factual summaries with source and review date on the individual pages.