Follistatin 315 vs AOD-9604
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315Fat Loss & Metabolic
AOD-9604- 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.
- AOD-9604 is a modified fragment of human growth hormone (residues 177-191) with an additional tyrosine residue that significantly enhances bioavailability. Originally developed as an anti-obesity drug by Metabolic Pharmaceuticals, it stimulates lipolysis and inhibits lipogenesis without the diabetogenic effects of full GH.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- 30-45 minutes injectable; longer with nasal spray formulation
- Admin Route
- SubQ, IM
- SubQ, Intranasal, Oral
- Research
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- Typical Dose
- No established human dosing protocol
- 300-600 mcg
- 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
- Selective fat loss without anabolic side effects
- No effect on blood glucose or insulin resistance
- Improved bioavailability over Fragment 176-191
- GRAS (Generally Recognized As Safe) status in Australia
- Potential cartilage repair and anti-inflammatory properties
- Does not suppress natural GH production
- 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
- Localized injection site reactions
- Headache (rare)
- Hypoglycemia risk in combination with insulin (very rare)
- Stacks With
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