New — Free Peptide Starter Guide (2026): 13 chapters, 34 cited studies

Get it free
ToolsCompareTripeptide-29 vs PE-22-28

Tripeptide-29 vs PE-22-28

Side-by-side comparison of key properties, dosing, and research.

Skin & CosmeticAnti-Aging & Longevity
Tripeptide-29
Cognitive Enhancement
PE-22-28
Summary
Tripeptide-29 is a pro-collagen cosmetic peptide composed of proline, hydroxyproline, and glycine — the core repeating unit of collagen. Applied topically, it signals dermal fibroblasts that collagen degradation has occurred, triggering compensatory new collagen synthesis.
PE-22-28 is a synthetic analog of spadin derived from sortilin, designed to block TREK-1 potassium channels with rapid-onset antidepressant and neurogenic effects. It shows fast-acting depression relief (within 24 hours) and promotes hippocampal neurogenesis.
Half-Life
Not applicable (topical)
Relatively short; CNS effects may persist due to neurogenic mechanisms
Admin Route
Topical
SubQ, Intranasal
Research
Typical Dose
0.01-0.1% in formulation
200–400 mcg
Frequency
Once or twice daily
Once daily
Key Benefits
  • Stimulates fibroblast collagen synthesis via damage-signal mechanism
  • Reduces fine lines and improves skin smoothness
  • Supports dermal matrix integrity
  • Naturally bioidentical to collagen fragment sequences
  • Well-tolerated in all skin types
  • Synergistic with copper peptides and retinoids
  • Rapid-onset antidepressant effects (within 24 hours)
  • Promotes hippocampal neurogenesis
  • Improves cognitive performance and memory
  • Reduces anxiety and depressive behavior
  • Novel mechanism — does not act on serotonin/dopamine/GABA receptors directly
  • May help treatment-resistant depression
  • Neuroprotective effects
Side Effects
  • Excellent tolerability profile
  • No documented significant adverse effects at cosmetic concentrations
  • Rare sensitivity reactions in individuals with peptide allergies
  • Generally well tolerated in animal models
  • Limited human data available
  • Possible mild headache or transient mood changes at initiation
  • Injection site reactions (SC)
Stacks With