Follistatin 344

Follistatin 344 (FS-344) is a naturally occurring glycoprotein that inhibits myostatin and activin A, members of the TGF-β superfamily that suppress muscle growth. The FS-344 gene encodes a 344-amino acid precursor that is cleaved to produce the circulating FS-315 isoform. Gene therapy studies in primates and human clinical trials for muscular dystrophy have demonstrated significant muscle hypertrophy and strength gains. However, injectable peptide use has very limited human data, a short half-life (~90 minutes), and most research involves gene delivery rather than exogenous peptide administration. Follistatin has been banned by WADA since 2019.

• Myostatin Inhibition
• Activin A Blockade
• Satellite Cell Activation

Myostatin and activin A inhibition, potential muscle growth enhancement, studied for muscular dystrophy therapy

Binds and neutralizes myostatin and activin A, preventing their interaction with ActRIIB receptors on muscle cells. This blocks TGF-β signaling that normally suppresses muscle growth, allowing enhanced hypertrophy.

Peak plasma concentration: 9 min. Elimination half-life: 1.5 hrs. Largely cleared by: ~7.5 hrs.

Research protocols from published literature — not dosing recommendations.

• IGF-1 LR3 — Unknown: Both promote muscle growth through different pathways. Theoretical synergy but no studies on combination. Increased anabolic signaling may compound risks.
• BPC-157 — Unknown: Different mechanisms - BPC-157 promotes tissue repair while follistatin inhibits growth suppressors. No interaction data available.
• TB-500 — Unknown: Both involved in tissue regeneration through different pathways. No published studies on combination effects.
• CJC-1295 — Unknown: Some protocols combine follistatin with GH secretagogues. Different mechanisms but no safety data on combinations.
• HGH — Monitor Combination: Both promote anabolic effects. Theoretical additive muscle growth but combined use increases risk of excessive growth factor stimulation. No clinical data.
• Testosterone/Androgens — Monitor Combination: Androgens increase muscle mass through androgen receptors while follistatin inhibits myostatin. Combined use studied in some animal models but human data lacking.
• ACE-031 — Avoid Combination: Both target myostatin pathway. ACE-031 was discontinued due to vascular side effects. Combining myostatin inhibitors may increase adverse event risk.
• Other Myostatin Inhibitors — Avoid Combination: Stacking multiple myostatin inhibitors provides no proven benefit and may increase risk of off-target TGF-β pathway disruption.

Supplies:

• Follistatin 344 lyophilized powder (typically 1mg vial)
• Bacteriostatic water or sterile water
• Insulin syringes (29-31 gauge)
• Alcohol prep pads

1. 1Store lyophilized powder at -20°C until use
2. 2Add sterile/bacteriostatic water slowly down vial side
3. 3Gently swirl - do not shake vigorously as protein may denature
4. 4Solution should be clear - discard if cloudy
5. 5Use reconstituted solution within 7 days
6. 6Store reconstituted solution at 2-8°C, never freeze

Week 1-2: No reliable timeline established for injectable peptide use. Week 2-4: Gene therapy studies showed measurable changes by week 8. Important: Most dramatic results (15% muscle increase) are from gene therapy providing sustained expression, not short-acting injections. Injectable peptide effects likely much more modest due to rapid clearance.

CRITICAL: Most safety data is from gene therapy, not injectable peptide. Gene therapy trials showed no serious adverse events in BMD patients. Potential FSH suppression - may affect reproductive function. Minor LDL cholesterol increase reported (~8 mg/dL) in some subjects. Theoretical concerns: bone density reduction, organ fibrosis with chronic TGF-β inhibition. Case report of vision impairment at 10x dose - never exceed recommended amounts. Not recommended for those with active cancer due to growth factor modulation. Contraindicated in pregnancy - follistatin affects reproductive signaling.

CRITICAL: Most safety data is from gene therapy, not injectable peptide. Gene therapy trials showed no serious adverse events in BMD patients. Potential FSH suppression - may affect reproductive function. Minor LDL cholesterol increase reported (~8 mg/dL) in some subjects. Theoretical concerns: bone density reduction, organ fibrosis with chronic TGF-β inhibition. Case report of vision impairment at 10x dose - never exceed recommended amounts. Not recommended for those with active cancer due to growth factor modulation. Contraindicated in pregnancy - follistatin affects reproductive signaling.

Follistatin 344 should be stored at Lyophilized: -20°C. Reconstituted: 2-8°C, use within 7 days.