Cognitive
P21
Longevity
4
Amino acids
Molecular weight
Peptide
Type
P21 (also designated P021 or Peptide 6) is a synthetic hexapeptide (Ac-DGGLAG-NH2) derived from the tetrapeptide core at CNTF residues 148–151, extended with an adamantylated glycine at the C-terminus to enhance blood-brain barrier permeability and resist exopeptidase degradation. It promotes adult hippocampal neurogenesis by upregulating BDNF expression and competitively inhibiting leukemia inhibitory factor (LIF) signaling that suppresses neural progenitor proliferation. P21 is studied primarily in preclinical models of Alzheimer's disease and age-related cognitive decline.
Top researched benefits
Overview of P21
P21 binds to CNTF receptor epitopes to inhibit LIF signaling, which normally suppresses neural progenitor cell proliferation, while simultaneously upregulating BDNF expression and activating the TrkB–PI3K–Akt–GSK-3β pathway to inhibit GSK-3β activity (phosphorylation at Ser9). This dual action promotes hippocampal neurogenesis, reduces tau hyperphosphorylation, and enhances synaptic plasticity through upregulation of glutamate receptor expression and dendritic spine formation.
neurodegenerative disease
- P021 markedly reduced tau pathology, attenuated Aβ generation, and rescued episodic memory impairment in 3xTg-AD mice.
- Treatment during synaptic compensation period can prevent neurodegeneration and reduce mortality.
- Robust attenuation of tau pathologies through BDNF/TrkB/PI3-K/AKT/GSK3β pathway.
cognitive enhancement
- Enhances dentate gyrus neurogenesis so effectively it exceeds levels in healthy untreated brains.
- Enhances memory processes through increased BDNF and restored synaptic function.
- May reduce natural decline in learning and memory in aged models by rescuing neurogenesis deficit.
neuroprotection
- Restores synaptic deficits in cortex and hippocampus.
- Rescues deficits in neuronal plasticity.
Typical Dose
250mcg per administration (speculative; extrapolated from animal models — no validated human dose exists)
Frequency
once daily
Cycle Duration
up to 12 weeks, based on preclinical protocols
Storage
Lyophilized: -20°C, stable 12–24 months. Reconstituted in bacteriostatic water: 2–8°C for up to 28 days; protect from light.
Chemical Makeup
Key benefits
Promotes adult hippocampal neurogenesis in aged and diseased animal models by upregulating BDNF and inhibiting LIF-mediated suppression of neural progenitors
Reduces tau hyperphosphorylation and slows amyloid-beta pathology progression in triple-transgenic Alzheimer's disease mouse models
Enhances short-term memory and spatial reference memory in normal adult mice after peripheral administration
Rescues episodic memory impairments and dramatically reduces mortality rates in 3xTg-AD mouse models (87% vs 41% survival at week 71)
Community interest
This peptide is still gaining traction in the community.
CNTF Mimetic | Neuroprotection & Cognitive Enhancement
This overview is informational and based on aggregated descriptions from studies and user reports.
Was it helpful?YesNoP21 Molecular Information
View the scientifc details of P21.
4
Amino Acids
P21
Asp
Asp
Position 1
Gly
Gly
Position 2
Gly
Gly
Position 3
Leu
Leu
Position 4
Molecular Weight
578.3DaChain Length
4Amino AcidsType
PeptideP21 Protocols
Subcutaneous injection is an established route for P21, delivering the CNTF-derived peptide systemically for neurogenic and neuroprotective effects. Preferred sites include the abdomen, thighs, or upper arm, with morning administration most commonly used in research protocols.
| Goal | Dosage | Frequency | Route |
|---|---|---|---|
| Begin neurogenic stimulation at a conservative dose to establish tolerance over 2–4 weeks before escalating | 250 | 1 day range | SubQ |
| Sustain cumulative neuroplasticity and working memory improvement through a full 8–12 week cycle | 500 | 1 day range | SubQ |
| Maximize neurotrophic signaling in experienced users who have completed at least one standard cycle without adverse effects | 1000 | 1 day range | SubQ |
| Support long-term tau pathology reduction and neuronal survival as studied in preclinical Alzheimer's models | 500 | 1 day range | SubQ |
| Maintain baseline neurotrophic factor activity and protect against age-related cognitive decline at a low maintenance dose | 250 | 1 day range | SubQ |
Reconstitution Instructions
Materials needed:
Steps to reconstitute
- Allow the lyophilized P21 vial to reach room temperature before opening to prevent condensation inside the vial
- Draw the desired volume of bacteriostatic water into an insulin syringe — a 5 mg vial reconstituted with 2.5 mL yields 2000 mcg/mL (20 mcg per unit on a U-100 syringe)
- Inject the bacteriostatic water slowly down the inner wall of the vial — never squirt directly onto the lyophilized powder
- Gently swirl the vial until the powder is fully dissolved — do not shake, as agitation can degrade the peptide
- Inspect the solution — it should be clear and colorless; discard if cloudy or discolored
- Store the reconstituted vial refrigerated at 2–8°C and use within 28 days
- Wipe the injection site with an alcohol swab and allow it to air dry
- Pinch a fold of skin at the chosen site (abdomen, thigh, or upper arm) and insert the needle at 45–90 degrees
- Inject slowly over 5–10 seconds, then withdraw the needle and apply gentle pressure with a gauze pad
- Rotate injection sites with each administration to prevent tissue irritation
P21 Cycle
The P21 Cycle section explains how long a typical cycle lasts and what to expect during each phase. Over time, your body can become less responsive with continuous use.
Taking breaks between cycles may help maintain effectiveness and support better overall results.
- Week 0-0
- BDNF elevation begins
- Week 0-0
- Neurogenesis enhancement measurable
- Week 0-0
- Cognitive improvements in research models
- Week 0-0
- Disease-modifying effects in AD models
Dosing tools
P21 Peptide Dosage Calculator
Calculate peptide doses with our visual syringe guide.
mg
Enter the total amount of peptide in the vial in milligrams (as stated on the label).
The dose you want to inject per administration, in mcg or mg.
1,000 mcg = 1 mg
1 mL
2 mL
3 mL
5 mL
Custom
Volume of bacteriostatic water you add to reconstitute the powder. Use BAC water for preservation.
Injection Results
Based on your vial and dilution inputs.
P21
SINGLE COMPOUNDVolume per injection
0.05
mL
Concentration
10.00
mg/mL
Doses per vial
20
doses
Total injections per vial
20 injections
How it works
Based on a 10 mg P21 vial diluted with 1 mL of bacteriostatic water, each 500 mcg injection equals 0.05 mL.
1mL / 100 units
5 units
0.050 mL
Reference Guide
Dosing Cycle
- Peptide
- P21
- Dosing
- 250mcg per administration (speculative; extrapolated from animal models — no validated human dose exists)
- Dosing Frequency
- once daily
- Cycle Duration
- up to 12 weeks, based on preclinical protocols
- Storage
- Lyophilized: -20°C, stable 12–24 months. Reconstituted in bacteriostatic water: 2–8°C for up to 28 days; protect from light.
Note: Triple agonist; microdose for fewer side effects
Reconstitution Tips
- Use bacteriostatic water (BAC) — contains 0.9% benzyl alcohol for preservation
- Inject water slowly — aim down the vial wall, not directly onto powder
- Never shake — gently swirl or roll the vial until dissolved
- Store properly — refrigerate at 2-8°C after reconstitution
- Use within 28 days — most reconstituted peptides remain stable for about 4 weeks
- Keep sterile — always clean vial tops with alcohol before drawing
Peptide Interactions
Research suggestions of P21 interactions with other common peptides and substances.
Cognitive
dih
Longevity
Dihexa
COMPATIBLE
Both promote neurogenesis through different pathways.
Cognitive
sema
Longevity
Semax
COMPATIBLE
Different nootropic mechanisms; may complement each other.
Side effects
Contraindications
Not approved for human use
Pregnancy or breastfeeding
Unknown safety profile in humans
Stop signs
Allergic reactions
Unusual neurological symptoms
Bad signs
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Frequently asked questions
What is a peptide dosage calculator?
A peptide dosage calculator is a free tool that converts your vial size, bacteriostatic water volume, and target dose into an exact syringe draw volume. Instead of doing the reconstitution math by hand, you enter three inputs and instantly get the concentration of your solution and how many milliliters or syringeunits to draw. This calculator works for single peptide compounds and multi-peptide blends.
How do I calculate peptide dosage from a vial?
To calculate your peptide dose, divide the total peptide content of your vial in micrograms by the volume of bacteriostatic water you added in milliliters. This gives you your solution concentration in mcg/mL. Then divide your target dose by that concentration to get your draw volume. For example, a 5mg (5,000 mcg) vial reconstituted with 2mL of BAC water gives a concentration of 2,500 mcg/mL. A 250 mcg dose would require drawing 0.1mL. This calculator automates all of those steps instantly.
How much Bacteriostatic water should I add to a peptide vial?
Most people add 2mL to 3mL of bacteriostatic water per vial, but the right amount depends on the dose you want to draw and the syringe size you are using. Adding 1mL to a 5mg vial gives you a concentration of 5,000 mcg/mL, making each dose very small in volume. Adding 2mL gives you 2,500 mcg/mL, which is easier to measure on a standard insulin syringe. A general guideline is to choose a volume that puts your typical dose somewhere between 10 and 30 units on a U-100 syringe. Use the calculator above to test different water volumes and find what works for your dose.
How are peptides different from proteins?
Both are made of amino acids, but peptides are much smaller than proteins. Because of their tiny size, peptides can act like tiny messengers in the body, sending specific signals to your cells to tell them exactly what to do.
P21Research References
P21 is a preclinical compound
P21
P21 is a preclinical compound
P021 Treatment in 3xTg-AD Mice
P021 markedly reduced tau pathology, attenuated Aβ, rescued episodic memory, and reduced mortality in AD mice.
n.d.
P21 and BDNF/TrkB Pathway
Disease-modifying effect via BDNF/TrkB/PI3-K/AKT/GSK3β pathway; rescued neurogenesis and cognition.
n.d.
P21 in Cognitive Aging
May reduce age-related cognitive decline by restoring BDNF expression and synaptic function.
n.d.
P21 as Promising AD Drug Candidate
Beneficial effects in preclinical studies make P21 highly promising for AD drug development.
n.d.
Calculate peptide dosages
Learning how to calculate a peptide dose? Use our beginner-friendly peptide dosage, blend, and accumulation calculators. Enter vial size, reconstitution volume, and target dose to get exact draw volumes instantly. No guesswork, just clear guidance that helps prevent common mistakes.
