Follistatin-344

FST-344 · Follistatin

Rank#999
Growth HormoneNot ApprovedPhase IResearchSubQ

Popular for:Myostatin inhibition, muscle growth, muscular dystrophy research

4

Total Studies

3

Human Studies

Phase I

Evidence Level

Not Approved

FDA Status

Overview

Follistatin-344 is a synthetic version of the naturally occurring follistatin protein, which functions as an inhibitor of myostatin and activin signaling. Myostatin is a negative regulator of muscle growth — by binding and neutralizing myostatin, follistatin effectively removes the body's natural brake on muscle development.

Follistatin gained public attention through gene therapy experiments where mice treated with follistatin gene therapy developed dramatically increased muscle mass. The synthetic injectable form (Follistatin-344 and the related Follistatin-315) allows researchers to study myostatin inhibition without gene therapy approaches.

Mechanism of Action

Follistatin-344 binds directly to myostatin and activin A, preventing them from interacting with their receptors (ActRIIB). This neutralization removes the signaling that normally limits muscle fiber growth and proliferation. Follistatin also binds FSH (follicle-stimulating hormone) in the reproductive system, which is why the 315 isoform (which doesn't bind FSH) is sometimes preferred in research.

Key Research Benefits

Potent myostatin inhibitor — removes natural muscle growth limit
Studied for significant lean muscle mass increases
Researched for muscle wasting conditions (sarcopenia, cachexia)
Gene therapy version showed dramatic results in animal models
May support muscle recovery and regeneration

Clinical Evidence Summary

Research Pipeline

Preclinical
Animal
Phase I
Phase II
Phase III
Approved

4

Total Studies

3

Human Studies

Not FDA-approved. Gene therapy version (AAV-FS344) in clinical trials for inclusion body myositis and muscular dystrophy. Injectable form is a research compound. Regulatory risk due to gene doping concerns in sports.

Key Studies / PubMed References

Detection of black market follistatin 344.

Review

Reichel C, Gmeiner G, Thevis M · Drug testing and analysis · 2020

PMID: 33460286

Central serous chorioretinopathy associated with high-dose follistatin-344: a retrospective case series.

Human Study

Dağ U, Çağlayan M, Öncül H, et al. · International ophthalmology · 2020

PMID: 32671599

Detection of black market follistatin 344.

Review

Reichel C, Gmeiner G, Thevis M · Drug testing and analysis · 2019

PMID: 31758732

The transgenic expression of human follistatin-344 increases skeletal muscle mass in pigs.

Animal Study

Chang F, Fang R, Wang M, et al. · Transgenic research · 2017

PMID: 27787698

Side Effects & Safety

Potential effects on reproductive hormones (FSH binding)
Joint and tendon stress from rapid muscle growth
Limited human safety data for injectable form
Theoretical cancer concerns (removing growth regulation)
High cost

Known Interactions

No curated interaction entry is live for Follistatin-344 yet.

Until the interaction table is fully populated, use the interaction checker and related peptides below to explore adjacent compounds and likely research pairings.

Frequently Asked Questions

Research Disclaimer

This page is for research and educational purposes only. The information presented is based on published scientific literature and does not constitute medical advice, diagnosis, or treatment recommendations. Follistatin-344 is not approved by the FDA for human therapeutic use. Always consult a qualified healthcare professional before making any health-related decisions. The studies referenced are linked to their original PubMed sources for verification.