P21 vs Synapsin
A side-by-side research comparison of P21 and Synapsin across mechanism, dosing, half-life, benefits, side effects and research status.
Comparison table
| Attribute | P21 | Synapsin |
|---|---|---|
| Full name | P21 (CNTF-Derived Tetrapeptide) | Synapsin Nasal Spray (RG3 + NAD+ + Methylcobalamin) |
| Category | Cognitive & Nootropic | Cognitive & Nootropic |
| Status | Research compound | Compounded medication |
| Mechanism | Mimics CNTF neurogenesis-enhancing portion by increasing BDNF and activating PI3K/Akt. Inhibits LIF signaling to selectively promote neural stem cell proliferation. | Rg3 reduces neuroinflammation and protects neurons. NAD+ supports mitochondrial function and sirtuin activation in brain cells. Methylcobalamin provides methylation support and myelin repair. Nasal route bypasses BBB for direct CNS delivery. |
| Molecular weight | ~450 Da | Combination compound |
| Half-life | 4-6 hours | Variable (nasal depot effect) |
| Bioavailability | Moderate (crosses BBB) | ~60-80% nasal (direct CNS access) |
| Typical dose | 50-100 mcg/kg | 1-2 sprays per nostril |
| Frequency | Daily | 1-2x daily |
| Route | Intranasal or Subcutaneous | Intranasal spray |
P21 reported benefits
- Hippocampal neurogenesis
- BDNF increase
- Cognitive enhancement
- BBB penetrant
- No appetite suppression
- Dendritic branching
Synapsin reported benefits
- Improved mental clarity
- Reduced brain fog
- Neuroprotection
- Enhanced focus
- Nerve repair support
- Anti-neuroinflammatory
Related comparisons
Research and educational reference only. Not medical advice.