P21

Mechanism

Associated with BDNF up-regulation and synaptic plasticity enhancement.

Reported effects

What sources associate with this compound. Reported categories, not outcomes we have graded — each would need its own citation and rung.

• Motor learning
• Neuroplasticity
• Post-TBI recovery

Reconstitution

mass ÷ diluent = concentration; dose ÷ concentration = volume; volume × the syringe factor = units on the barrel (100 for U-100, 40 for U-40). Run your own numbers.

Literature on file 6

• animal in vivo
  Effects of a ciliary neurotrophic factor (CNTF) small-molecule peptide mimetic in an in vitro and in vivo model of CDKL5 deficiency disorder. graded on: an animal model — read from the indexed abstract — “mice”
• animal in vivo
  Diffusion MRI measures detect brain microstructure changes due to early treatment with neurotrophic peptide mimetic P021 in the 3xTg-AD mouse model of Alzheimer's disease. graded on: an animal model — “mouse”
• animal in vivo
  Neurotrophic Treatment Initiated During Early Postnatal Development Prevents the Alzheimer-Like Behavior and Synaptic Dysfunction. graded on: an animal model — read from the indexed abstract — “mice”
• animal in vivo
  Prenatal to early postnatal neurotrophic treatment prevents Alzheimer-like behavior and pathology in mice. graded on: an animal model — “mice”
• animal in vivo
  Prevention of dendritic and synaptic deficits and cognitive impairment with a neurotrophic compound. graded on: an animal model — read from the indexed abstract — “Mice”
• animal in vivo
  Early neurotrophic pharmacotherapy rescues developmental delay and Alzheimer's-like memory deficits in the Ts65Dn mouse model of Down syndrome. graded on: an animal model — “mouse”

What is circulated not evidence 5

Claims passed around in community guides and vendor copy, recorded because they circulate — not because they are true. Each is shown with the page it was read from and what this record actually holds. Checked 2026-08-24.

• unverified community data dose common contradicts the record

  Roughly 500 mcg to 1 mg once daily is the most-repeated dose, within a broader cited range of about 100 mcg to 2 mg a day, and one guide states every value is anecdotal and vendor-derived.

  every value is anecdotal and vendor-derived.

  On the record The record holds 100-500 mcg per administration daily, and marks it unverified. The lower bounds agree; the circulated upper bound of 2 mg is four times the maximum on file. The record's dosing has no cited source, and molecular weight, formula, CAS number, sequence and half-life are all not on file.

  Source 1 · Source 2 · Source 3

• unverified community data dose common nothing on file either way

  Intranasal administration is widely recommended over injection on the grounds of direct nose-to-brain delivery, while the original rodent studies used oral and peripheral dosing.

  There is no clinically established dose, because no human clinical trial has ever defined one.

  On the record No route is on file for p21, and the record names that absence rather than papering over it. The community has filled the gap with a route that does not match the animal studies the compound's grading rests on.

  Source 1 · Source 2

• unverified community data side effect common nothing on file either way

  Sleep disruption or overstimulation is the most frequent community complaint, which is why morning-only dosing is advised; injection-site reactions and headache are also reported.

  sleep disruption or overstimulation

  On the record No side effect is on file for p21. The single most-reported effect in the community, and the timing rule derived from it, has no entry in the record.

  Source 1

• unverified community data storage common nothing on file either way

  A specific reconstitution recipe circulates: a 5 mg vial in 2 to 2.5 mL of bacteriostatic water, giving about 0.20 mL for a 500 mcg dose, or 25 units daily for a ten-day course.

  ~0.20 mL

  On the record Nothing on file. The record holds no reconstitution or storage entry for p21. A ten-day course also conflicts with the 4-8 week cycle on file.

  Source 1 · Source 2

• unverified community data titration common agrees with the record

  Courses of four to eight weeks with time off are the community convention.

  4-8 weeks, with time off

  On the record The record holds a cycle of 4 to 8 weeks, matching exactly. Neither the record nor the community can name a study behind those numbers; the record's grading rests on an animal model.

  Source 1

Identity

Classified as

BDNF/TrkB Signalingmechanism

Nearly every nootropic record on the site points here, so it is where a cognitive claim can be checked against something measurable instead of taken as a description of how someone felt.

Neuroplasticitypathway

Nearly every nootropic claim reduces to a claim about this pathway, and the supporting measurement is usually a protein level in rodent brain tissue, an animal_in_vivo finding that does not carry across to human cognition.

Also called

• P21

Listed prices 47

What 33 shops we track listed for P21, read from their own public catalogues on 2026-09-14. We take no commission on these and they are not ranked by any payment — how vendors are scored.