P21
P021 · CNTF-derived peptide · Ciliary Neurotrophic Peptide
CNTF C-terminal fragment, not FGL, not Semax. Animal neurogenesis and metabolic papers are not a human TBI or amyloid protocol.
Use-case scores
0–10 against the evidence we have, not a gym ranking. Hidden domains do not apply here.
- Cognition3/10
Neurotrophic fragment in animal models. Not a human nootropic RCT.
- Metabolic / weight3/10
Hypothalamic energy-expenditure animal data. Not a GLP-1 and not a fat-loss label.
Compound card
- Sequence
- CNTF C-terminal fragment (21 aa)
- Class
- Preclinical CNTF-derived peptide (not FGL)
- Formula
- C-terminal CNTF fragment (21 AA)
- Status
- Not FDA-approved · research use
How it works
P21 is a 21-amino-acid fragment (C-terminal portion) of ciliary neurotrophic factor (CNTF). It was identified through structure-activity relationship studies on CNTF to isolate the neurotrophic and metabolic activity without receptor coupling to the JAK/STAT pathway.
P21 promotes neurogenesis, axonal regeneration, and optic nerve repair in preclinical models. It also has significant effects on hypothalamic energy regulation - animal studies showed marked fat mass reduction, improved insulin sensitivity, and increased energy expenditure without reducing food intake or causing cachexia. The metabolic mechanism involves direct activation of hypothalamic AMPK and changes in neuropeptide Y (NPY) / proopiomelanocortin (POMC) signaling.
Source: PMID: 23877024
Background & History
P21 is a CNTF C-terminal fragment, not FGL, not Semax. Animal neurogenesis and metabolic papers are not a human TBI or amyloid protocol.
Research Use Cases
- ✓CNTF-fragment identity vs FGL vs Semax
- ✓Preclinical Alzheimer-model papers as animal work, not a human indication
- ✓Not a TBI or Parkinson treatment page
Dosing
| Phase | Dose | Frequency | Notes |
|---|---|---|---|
| Research Protocol | 1 - 5 mg | 3x per week SC (research dosing) | Based on preclinical scaling. No established human dosing. Very limited human data. |
Administration
Timeline
Who it is for
Neuroprotection / Neural Repair
LowStrong preclinical data for axonal regeneration and optic nerve repair. Human data lacking.
Metabolic / Fat Loss
LowHypothalamic energy regulation effects in animals. No human clinical data.
Reconstitution
Safety & Considerations
Research compound. No established human safety data. Use only under medical supervision. Preclinical studies show favorable profile.
Regulatory & Legal Status
Not currently on the WADA 2026 Prohibited List. Policies may change - verify before competition.
Research Chemical
US Compounding: Not eligible / not available
⚠️ This information is for educational purposes only and may not reflect the most current regulatory updates. Always verify with official FDA, WADA, and jurisdiction-specific sources before use.
Limits of current evidence
- Different molecule from FGL (NCAM FG loop).
- This site will not treat obesity or neurodegeneration from this leaf.
Verdict
P21 is a CNTF fragment, not FGL, not Semax. Animal neurogenesis and metabolic papers are not a human protocol. Do not treat optic-nerve animal work as an eye drug.
Interactions & Contraindications
Research compound, thin human file. This site will not treat Alzheimer disease from a peptide page.
Synergies & Common Stacks
Different molecules. Complementary neurogenesis marketing is not a combo RCT.
Frequently Asked Questions
What does P21 do?▼
References
- Sleeman MW et al. “"A CNTF-related peptide receptor modulator promotes fat loss".” Endocrinology (2003). PMID: 12949240
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