Follistatin 315 vs AHK-Cu
Side-by-side comparison of key properties, dosing, and research.
Anabolic & IGF
Follistatin 315Skin & CosmeticAnti-Aging & Longevity
AHK-Cu- 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.
- AHK-Cu is a copper tripeptide composed of alanine, histidine, and lysine chelated to copper. Distinct from GHK-Cu, AHK-Cu exhibits strong affinity for hair follicle receptors and demonstrates potent hair growth stimulation alongside wound healing and skin regeneration properties.
- Half-Life
- ~3–5 hours (longer systemic circulation vs FST-344)
- Hours (topical, variable by formulation)
- Admin Route
- SubQ, IM
- Topical, Scalp application, Subcutaneous (research)
- Research
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- Typical Dose
- No established human dosing protocol
- 0.01–0.1% concentration
- Frequency
- Research use only
- Once or twice 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
- Stimulates hair follicle growth and reduces shedding
- Increases dermal papilla cell proliferation
- Promotes wound healing and skin regeneration
- Antioxidant protection via superoxide dismutase activation
- Improves skin elasticity and firmness
- Supports collagen and elastin 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
- Generally well-tolerated topically
- Mild scalp irritation or redness in sensitive individuals
- Possible temporary hair shedding phase at treatment initiation
- Copper accumulation with excessive systemic use (rare)
- Stacks With
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