PinnyPeptide

B7-33 vs Follistatin

Side-by-side comparison: effects, dosing ranges, side effects, regulatory status, and reconstitution.

Peptide A

B7-33

Muscle Growth

Single-chain relaxin peptide analog with anti-fibrotic and cardioprotective activity.

Peptide B

Follistatin

Muscle Growth

Endogenous activin/myostatin binding protein — the gene-therapy myostatin inhibitor.

Typical vial

2 mg

Typical dose

1000-2000 mcg

Half-life

~2-3 hours

FDA status

Not FDA approved.

Typical vial

1 mg

Typical dose

100-300 mcg

Half-life

~30 minutes (recombinant); years (AAV expression)

FDA status

Not FDA approved as recombinant protein. AAV-Follistatin gen…

B7-33 effects

  • Anti-fibrotic action in heart, lung, kidney tissue
  • Activates RXFP1 receptor via cGMP signaling arm
  • Vasodilatory effects
  • May support tissue remodeling and scar prevention
  • Reduces collagen deposition in injury models

Follistatin effects

  • Binds and neutralizes myostatin, activin A, and GDF-11
  • Promotes skeletal muscle hypertrophy
  • Increases muscle fiber size and strength
  • May enhance recovery from muscle injury
  • Sustained effect when delivered via AAV gene therapy

B7-33 side effects

  • Human safety data essentially absent
  • Theoretical: hypotension from vasodilation
  • Injection-site reactions
  • Possible effect on uterine / cervical tissue (relaxin family)

Follistatin side effects

  • Limited human safety data for recombinant protein
  • Theoretical disruption of HPG axis (activin binding)
  • Injection-site reactions
  • Potential off-target effects on tissues using activin signaling

B7-33 dosing ranges

Research / anti-fibrotic

1-2 mg · Daily (SubQ or IV in preclinical work) · Per research protocol

Follistatin dosing ranges

Research / muscle hypertrophy (recombinant)

100-300 mcg · Daily (SubQ) · 10-30 days per cycle

AAV gene therapy (clinical)

Single high-titer AAV infusion · One-time · Durable expression (years)

Full B7-33 guide → Full Follistatin guide →

B7-33 vs Follistatin — common questions

What is the difference between B7-33 and Follistatin?

B7-33: Single-chain relaxin peptide analog with anti-fibrotic and cardioprotective activity. Typical dose 1000-2000 mcg. Follistatin: Endogenous activin/myostatin binding protein — the gene-therapy myostatin inhibitor. Typical dose 100-300 mcg. Both fall under the Muscle Growth category.

Can you stack B7-33 and Follistatin?

Stacking B7-33 with Follistatin is a protocol-design question best raised with a clinician — it depends on your goal, current bloodwork, and whether both peptides target overlapping mechanisms. Both peptides should be tracked independently with separate injection sites and timing. PinnyPeptide supports multi-peptide stacks with automatic injection site rotation.

Which is dosed more frequently, B7-33 or Follistatin?

B7-33 is typically dosed: Daily (SubQ or IV in preclinical work) for Research / anti-fibrotic. Follistatin is typically dosed: Daily (SubQ) for Research / muscle hypertrophy (recombinant); One-time for AAV gene therapy (clinical).

Are B7-33 and Follistatin FDA approved?

B7-33: Not FDA approved. Follistatin: Not FDA approved as recombinant protein. AAV-Follistatin gene therapy in clinical trials.

Related peptide comparisons

ace-031 vs b7-33ara-290 vs b7-33b7-33 vs bpc-157b7-33 vs gdf-8-95b7-33 vs igf-1-lr3ace-031 vs follistatin

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