Comparison
AOD-9604 vs. Follistatin (FST)
Two peptides side-by-side — identity, evidence base, legal status and known adverse events.
Identity
Category
Growth
Growth
CAS no.
221231-10-3
122956-17-2
Molecular weight
1815.09 g/mol
35000 g/mol
Half-life
0.4 h
no data
Sequence
Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-PheGlykoprotein, ~315 Aminosäuren in der zirkulierenden Hauptform (Sequenz isoformabhängig, kein einheitliches kurzes Peptid)Mechanism of action
AOD-9604
AOD-9604 corresponds to the C-terminal fragment 176-191 of human growth hormone with an additional N-terminal tyrosine. In animal models, lipolytic effects without GH-typical adverse events (insulin resistance, IGF-1 rise) were reported. In humans, these preclinical findings did not translate into clinically relevant weight reduction in the four phase-2 obesity trials. The exact human mechanism of action is unclear; the GH receptor is not classically activated by the fragment.
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.
Evidence base
Highest evidence
Human RCT
Human trial
Studies
3
4
of which in humans
2
1
Effects recorded
3
4
Open conflicts
1
1
Documented adverse events
1
1
Legal status
Full entries
Frequently asked questions
- What is the difference between AOD-9604 and Follistatin (FST)?
- AOD-9604 is classified as "Growth", while Follistatin (FST) is classified as "Growth". AOD-9604: Synthetic 16-amino-acid peptide corresponding to the C-terminal fragment of human growth hormone (hGH 176-191). Originally developed by Metabolic Pharmaceuticals as an oral obesity therapy; all phase-2 trials missed the primary endpoint. No marketing approval. The Australian TGA Schedule 4 classification is often misunderstood. 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. This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, AOD-9604 or Follistatin (FST)?
- The highest available evidence level is "Human RCT" for AOD-9604 and "Human trial" for Follistatin (FST). 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 AOD-9604 and Follistatin (FST) in Germany and the United States?
- Germany: AOD-9604 — Unapproved, Follistatin (FST) — Unapproved. United States: AOD-9604 — Unapproved, Follistatin (FST) — Unapproved. These are factual summaries with source and review date on the individual pages.