P21
Quick summary
A small peptide derived from ciliary neurotrophic factor (CNTF), studied in rodent models of neurogenesis. Research focus: neurogenesis models and CNTF-derived peptides. This page leads with SRP's low-and-slow starting dose.
Overview
A small peptide derived from ciliary neurotrophic factor (CNTF), studied in rodent models of neurogenesis.
Looking for research material? Simple Research Peptides lists P21 10mg for laboratory research use.
Mechanism
A CNTF-derived small peptide reported to increase neurogenesis in the hippocampus of rodents.
Research areas
- neurogenesis models
- CNTF-derived peptides
Storage & reconstitution
Supplied as a freeze-dried (lyophilized) powder in a sealed vial. Unopened vials are generally kept cold and away from light. Labs usually reconstitute it with bacteriostatic or sterile water, letting the liquid run down the vial wall and swirling gently instead of shaking. The solution is then kept refrigerated.
Recommended starting dose (low and slow)
| Starting dose | Low end of the studied range: 100 mcg. |
|---|---|
| Frequency | Reported schedules: 100–300mcg daily AM. |
| Reconstitution | Examples: 10mg vial + 2mL diluent (as listed). |
Studied higher doses
Studies have used doses up to the amounts below. Higher doses can be dangerous. Whether a person can reach them safely depends on height, weight, activity level, training and pre-existing conditions. We recommend following the lower starting dose above, and contacting SRP with any questions.
| Highest amount reported in studies | Top of the studied range: 300 mcg. These are range tops, not verified ceilings. |
|---|
Route and timing
Route: Subcutaneous injection after reconstitution is the route most often described in research protocols.
Timing: Pending - to be added by SRP
Cycle length and repeat
Pending - to be added by SRP
Half-life
Approximate, for Bobby's review: Not well characterized in published research.
Side effects
Pending - to be added by SRP
Suggested bloodwork and monitoring
Draft, for Bobby's review: CBC and comprehensive metabolic panel (kidney and liver function, electrolytes) before starting and again after a few weeks.
Cautions
Pending - to be added by SRP
Reconstitution calculator
Math aid only. It converts the numbers you enter; it is not dosing advice. For research use only. Prefilled with this page's vial size, reconstitution and low-and-slow starting dose where known; change any value.
Frequently asked questions
What is P21 studied for?
In research it is studied for neurogenesis models and CNTF-derived peptides. A CNTF-derived small peptide reported to increase neurogenesis in the hippocampus of rodents.
How is P21 given in research?
Subcutaneous injection after reconstitution is the route most often described in research protocols. See the dosing frequency block on this page for how often.
What amount should a researcher start with?
This page lists SRP's low-and-slow starting dose in the Recommended starting dose section. Higher amounts that appear in studies are listed separately with their safety context. Start with the lower dose and contact SRP with any questions.
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Last updated: October 19, 2026