Follistatin 315 vs ARA-290
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315Immune SupportRecovery & Repair
ARA-290- Summary
- Follistatin 315 is a splice variant isoform of follistatin produced by alternative mRNA processing. Unlike Follistatin 344 which is tethered to cell surfaces via heparan sulfate proteoglycans, FST-315 circulates freely in the bloodstream and has broader systemic distribution. It is the predominant circulating form and exerts systemic myostatin inhibition as well as FSH suppression, making it relevant to both muscle growth and reproductive endocrinology.
- ARA-290 is a synthetic 11-amino acid peptide derived from the helix B region of erythropoietin (EPO). Unlike EPO, it selectively activates the innate repair receptor (IRR) without stimulating hematopoiesis, providing tissue protection, anti-inflammation, and neuropathy relief.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- ~2–4 hours (SC administration)
- Admin Route
- SubQ, IM
- SubQ
- Research
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- Typical Dose
- No established human dosing protocol
- 4 mg (fixed dose)
- Frequency
- Research use only
- Once daily
- Key Benefits
- Systemic myostatin inhibition for whole-body muscle growth
- Freely circulating — broader tissue distribution than FST-344
- Strong FSH-suppressive activity useful in certain hormonal protocols
- Potential for greater anabolic effect across multiple muscle groups simultaneously
- May be more relevant to reproductive endocrinology applications
- Studied in gene therapy approaches for muscular dystrophy
- Reduces neuropathic pain from small fiber neuropathy
- Anti-inflammatory without immune suppression
- Tissue protection after ischemia/reperfusion injury
- Promotes nerve fiber regeneration
- Improves symptoms of sarcoidosis-associated neuropathy
- May reduce insulin resistance and improve metabolic health
- Shown to improve autonomic neuropathy symptoms
- Side Effects
- Systemic FSH suppression — significant concern for fertility
- Greater potential for off-target effects vs FST-344 due to systemic distribution
- Limited human safety data
- Potential cardiac hypertrophy with prolonged high-dose exposure
- Injection site reactions
- Mild fatigue at initiation
- Transient warm sensation post-injection
- Rare: mild headache
- Stacks With
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