Is the research real?

Yes. Published academic work from neuroscience groups, showing increased hippocampal neurogenesis and reduced tau pathology in mouse models. That is a better research base than most compounds in this category have. It is also entirely preclinical.

What does the adamantane group do?

It makes the peptide lipophilic enough to cross the blood–brain barrier and slows its breakdown. Without it, a peptide injected under the skin would not reach the brain at all.

Anti-aging & longevity

P21

P021 · Cel-N-adamantyl Ac-DGGL-NH2 · CNTF-derived peptide

PreclinicalReviewed 18 Aug 2026

P21 comes from actual neuroscience rather than from a vendor. It is a four-amino-acid fragment of ciliary neurotrophic factor, modified with an adamantane group to cross the blood–brain barrier and resist degradation. Same engineering as the other modified peptides here, applied to a growth factor instead of a nootropic.

The published work is in mouse models of Alzheimer's disease, from academic groups, and it is genuinely interesting: increased neurogenesis in the hippocampus, raised BDNF, and reduced tau pathology. That is a more substantive research base than most of what surrounds it in this category.

It is also entirely preclinical. No human has been studied on P21 in any trial, for anything, and the gap between a mouse model of Alzheimer's and a person is the gap where nearly every Alzheimer's drug candidate of the last thirty years has died.

How it works

P21 is derived from ciliary neurotrophic factor, a protein that supports neuron survival. The four-residue fragment retains the neurogenic activity without the size that would prevent it reaching the brain.

The adamantane modification does two things: it slows enzymatic breakdown, and it makes the molecule lipophilic enough to cross the blood–brain barrier. Both are necessary for a peripherally administered peptide to act centrally at all.

In mouse models it increases hippocampal neurogenesis, raises BDNF expression and reduces abnormal tau phosphorylation. Those are three different mechanisms of interest in dementia research. That is why the compound attracted academic attention.

None of this has been shown in a human. Neurogenesis in adult humans is itself a contested question, which makes the translation harder rather than easier.

Quick reference

Commonly described dose: 500 mcg–1.5 mg
How often: Once daily
Route: Subcutaneous or Nasal
Where: Abdomen, Thigh
Timing: No timing effect established.
Storage once mixed: Refrigerated, 21 days

These describe what sources report, not what you should do. Full detail and provenance in the dosing section below.

Price index

Per-milligram pricing across vendors arrives with the directory. We are recording prices now so the history exists when the page ships.

Vocabulary on this page

Evidence level: The category of human evidence behind a compound, from preclinical through to approved. Stated on every profile here as a category, not an adjective.
Injection site: Where on the body an injection is given. Rotating between sites is standard practice for anything given repeatedly.
Peptide: A short chain of amino acids: the same building blocks as a protein, in a chain short enough to behave differently.

The whole glossary →

Regulatory status — United States

Not approved anywhere and never studied in a human trial. Developed in academic research with associated patents; no clinical programme has reported. Sold only as a research chemical.

Last reviewed 18 Aug 2026. Regulatory positions in this category change frequently; we date this line so you can see how current it is.

What it is studied for

Each entry states the evidence behind it. We do not rank indications by effectiveness — for most compounds here, that would be a claim nobody can support.

Neurogenesis and cognitive decline

Published review

What the published research addressed.

EvidenceIncreased hippocampal neurogenesis, raised BDNF and reduced tau pathology in mouse models of Alzheimer's disease. No human study of any kind.

Cognitive enhancement in healthy people

Community practice

Why it is bought.

EvidenceNever studied. The animal work is in models of disease, where restoring a deficit is a different question from improving intact function.

Identity and clearance

Molecule

Class: Adamantylated tetrapeptide derived from ciliary neurotrophic factor
Length: 4 amino acids

The adamantane group exists to get it across the blood–brain barrier, not to change what it does once there.

Dose protocols reported in sources

Displayed for reference only. Every row says where it came from, and a trial protocol and a community convention are not the same kind of information. None of this is fed into the calculator, and none of it is a recommendation.

Dose protocols reported in sources, with the source of each.
Goal	Dose	Frequency	Route	Units, 5 mg vial	Source	Start this protocol
Commonly described community protocol	500 mcg – 1.5 mg	Once daily	SubcutaneousNo human pharmacokinetic study exists, so these are not scaled from anything. They are conventions that formed in the absence of data.	10–30 u	Community practice	Start this

Start this copies a row into a protocol of your own, which you can then edit. Where a source gave a dose range or an ambiguous frequency, those fields arrive empty — we will not pick a number on your behalf.

CheckRows marked community practice describe what people commonly do, drawn from public discussion. They are not derived from any trial and are not evidence that a dose is safe or effective.

Calculator

Work out what to draw

Pre-filled with a 10 mg vial as a worked example. These are not recommended values — change them to match the vial in front of you.

Draw to 20 units on a 1 mL U-100 syringe. That is 0.2 mL, containing 1 mg of P21.

Concentration5mg / mL

Volume drawn0.2mL

Doses per vial10doses

Per unit50mcg / unit

20 units sits exactly on a printed line.

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Bioalmanac performs arithmetic on values you enter. It does not recommend doses, schedules or compounds, and nothing here is medical advice. Confirm every calculation against your vial and syringe before drawing, and speak with a licensed healthcare provider.

Open this calculation in the full calculator

Units, concentration, bacteriostatic water — the glossary defines the vocabulary, and a unit is not a fixed volume.

Safety

Reported effects

EverythingCommunity practice
Unknown
No human study exists at any dose by any route.
HeadacheCommunity practice
Anecdotally reported
Consequences of driving neurogenesis in a healthy brainPublished review
Unknown
The animal work is in brains with disease. Adding neurons to a brain that is working normally is a different intervention, and not obviously a good one.

When to stop

Any new neurological symptom: persistent headache, visual change, confusion, mood change or seizure activity. Seek assessment.
Any allergic response: rash, hives, facial swelling or difficulty breathing. Seek urgent care.
An injection site that becomes hot, spreading or produces pus.

Interactions and situations that need care

Any neurological or psychiatric conditionAvoid
A compound that alters neurogenesis and growth factor signalling in the brain, with no human data, should not be added to a brain already behaving unpredictably.
Active or previous cancerAvoid
Growth factor signalling drives cell proliferation. Raising it deliberately in someone with malignancy has no supporting evidence and an obvious direction of concern.
Pregnancy and breastfeedingAvoid
Growth factor signalling is central to development, and there is no safety data at all.
Self-treating cognitive declineUse caution
Memory problems have many causes, several of them treatable and some urgent. Treating them with an unstudied compound instead of establishing the cause lets a diagnosable condition progress.

What to expect

HonestlyThere is no human efficacy data for this compound, so there is no evidence-based timeline to give. Any site publishing a week-by-week schedule of expected effects has invented it.

The research is genuine academic neuroscience, and it is entirely in mice.
No human has been studied on this compound in any trial.
Mouse models of Alzheimer's are where nearly every drug candidate of the last thirty years has looked promising and then failed.
The animal work is in diseased brains. Restoring a deficit and enhancing intact function are different questions, and only the first has been asked.
Dose figures are conventions, not scaled from any study.

Storage and handling

Freeze-dried powder: Refrigerated at 2–8 °C, protected from light.
After mixing: Refrigerated at 2–8 °C. Nasal solutions are handled more than injectables and are correspondingly easier to contaminate.
Long-term, frozen: Unopened powder is stable at −20 °C or colder.

Printable one-pager How to reconstitute a vial, step by step

Checking your vial

Research chemicals carry no manufacturing standard, so what the vial looks like is often the only quality signal available before you use it. More on assessing quality and COAs.

White cake, clear solution
Standard for a short peptide.
Collapsed cake or cloudy solution
Heat damage or degradation. Do not use it.

Questions

Is the research real?: Yes. Published academic work from neuroscience groups, showing increased hippocampal neurogenesis and reduced tau pathology in mouse models. That is a better research base than most compounds in this category have. It is also entirely preclinical.
What does the adamantane group do?: It makes the peptide lipophilic enough to cross the blood–brain barrier and slows its breakdown. Without it, a peptide injected under the skin would not reach the brain at all.

References

P21, a CNTF-derived peptide: neurogenesis and tau pathology in mouse models
Neuroscience and neurodegeneration literature, 2013 · Animal studies
Mouse models of Alzheimer's disease
Increased hippocampal neurogenesis, raised BDNF expression and reduced abnormal tau phosphorylation. No human studies have been conducted.
Commonly reported community protocols
Bioalmanac editorial summary of public community sources, 2026 · Not a study
Records dose and route patterns described in public discussion. Carries no evidential weight about safety or effect.

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Keep this page honest

If something here is wrong, out of date, or missing a source, tell us and we will fix it and say that we did.

Suggest a correction

This page is educational. It describes what published research reports, not what you should do. Peptides discussed here are largely not approved for human use, and nothing on Bioalmanac is medical advice. No clinician reviews these pages.

Page last updated 18 Aug 2026