No human data · Grade D
P21
P21 (CNTF-Derived Peptide)
Score
48 / 100
Origin
CNTF-derived
Route
Oral (animal studies)
Status
Preclinical only
TL;DR
01
A small synthetic peptide (P021) derived from the active region of ciliary neurotrophic factor (CNTF), designed to be brain-penetrant and orally active.
02
In aged rats, oral P021 reduced cognitive decline, boosted BDNF, and restored neurogenesis and synaptic markers — encouraging preclinical results.
03
It has never been tested in humans; there are no clinical trials, so it is rated No Human Data.
04
Its rationale (mimicking a neurotrophic factor to support neurogenesis) is shared with several other unproven neuro peptides.
05
It is a research compound with no approval, purity guarantee, or human safety data.
Human trials
None
no clinical data
Preclinical (aged rats)
Positive
cognition, BDNF, neurogenesis
Mechanism
CNTF-mimetic
neurotrophic/neurogenic
Approval
None
research compound
Human safety
Unknown
no data
Part 01 · How it works
Mechanism.
P021 is a small fragment engineered from CNTF, one of the body's nerve-growth factors, shrunk down so it can cross into the brain and be taken orally. In older rats, giving P021 slowed age-related memory decline, raised BDNF, and revived the birth of new neurons and synaptic connections. That's a promising preclinical package — but it is entirely animal data. No human has been studied, so whether any of it carries over to people, and at what safety cost, is unknown.
A shrunk-down copy of a natural nerve-growth factor that rejuvenated aging rat brains in the lab — with no human chapter written yet.
CNTF mimetic
Peptide derived from the active region of ciliary neurotrophic factor; small enough to cross the blood-brain barrier.
Neurogenic/neurotrophic
In aged rats, increased BDNF, hippocampal neurogenesis, and cortical/hippocampal synaptic markers.
Procognitive (animal)
Reduced age-dependent learning and memory decline in 22–24-month-old rats.
Evidence stage
Preclinical only; no human trials.
Part 02 · Dosing & administration
How it's taken.
Community-reported · unregulatedValues below reflect commonly reported community protocols for P21. These are anecdotal and unregulated — not clinically validated and not a recommendation. Provided for educational purposes only — this is not medical advice and not instructions for self-administration. Consult your healthcare provider before making any health decision.
Standard dose
500-1000 mcg
Subcutaneous injection or Intranasal · Once daily
Duration
4–6 weeks typical cycle
·
No human dose exists; community/vendor figures cluster at 500 mcg–1 mg/day SC or intranasal, framed as anecdotal, not trial-validated.
·
P021 (a CNTF-derived peptide); the mouse Alzheimer studies dosed it ORALLY in diet (Kazim & Iqbal), which does not convert to a human injection dose.
·
No published human trials, pharmacokinetics, or safety data; sold as a research chemical, not for human use.
Need help with reconstitution?
Use the free peptide calculator for dilution, unit conversion, and injection volume.
Part 03 · Safety
Side effects, rare serious events, who shouldn't.
Common
Human tolerability
No human data.
Unknown
Serious · rare
Long-term human safety
No human safety data.
Unknown
Neurotrophic/oncologic caution
As with growth-factor mimetics, unstudied long-term/abnormal-growth questions.
Theoretical
Product-quality risk
Research supply; purity/dose unknown.
Source-dependent
Absolute · do not use
×
Pregnancy or breastfeeding
×
Children under 18
×
Known hypersensitivity to P21 peptide or any component
×
Active seizure disorders (neurotrophin modulation may affect seizure threshold)
×
Intracranial tumors
Relative · discuss first
!
Everyone, for evidence-based use — no human data
!
Pregnancy or breastfeeding — no data
!
Active or prior cancer — growth-factor mechanism, theoretical concern
Interactions
Antidepressants (SSRIs, SNRIs)
P21 enhances neurotrophin signaling (BDNF/CNTF pathway); may have additive neurotrophic effects with antidepressants
Minor
Anticonvulsants
Neurotrophic peptides may alter seizure threshold; monitor seizure frequency
Moderate
Cholinesterase inhibitors
Additive neurotrophic/neuroprotective effects; theoretical benefit but monitor for cholinergic side effects
Minor
Labs to monitor
CMP (Comprehensive Metabolic Panel)
Baseline and every 3 months
Liver and kidney function
CBC with Differential
Baseline and every 3 months
General safety monitoring
BDNF Level (optional, research)
Baseline (optional, research context)
P21 may modulate neurotrophic factor signaling
Part 04 · Evidence
How strong is the evidence?
48
Grade D
Grade D, No Human Data. P021 has coherent CNTF-mimetic biology and encouraging aged-rat results, but no human trials and no human safety data — a preclinical candidate, not a therapy.
Mechanistic plausibility
Rational neurotrophic mechanism with supportive aged-rat data.
74
Human evidence
No human trials.
12
Safety & tolerability
No human safety data; neurotrophic mechanism carries the usual unstudied long-term questions.
42
Durability
No human outcome data.
45
Independence
Work largely from the originating group.
55
Part 05 · Research log
Every study we cite.
We list each study with its methodology, funding source, and our quality grade. Flagged studies aren't dismissed — they're tagged so you can weigh them.
01
2014
Neurobiology of Aging Flagged
Rescue of cognitive-aging by a neurogenic/neurotrophic compound (P021)
Oral P021 reduced age-dependent learning/memory decline, inhibited the neurogenesis deficit, raised BDNF, and restored cortical/hippocampal synaptic markers.
Aged-rat (22–24 mo) chronic oral dosing · Aged-rat study from the originating group; no human data.
PMID 24702821 ↗
Moderate (preclinical)
Evidence against
What didn't work, and where the evidence is thin.
Every publication is incentivized to tell you a peptide works. We catalogue the null results, failed trials, and mechanism limits we found in the same literature — so you can weigh them against the upside, with your provider.
01
Encouraging in aged rats — but no human data whatsoever
Mechanism limit Neurobiology of Aging · 2014
P021's cognitive and neurotrophic benefits are established only in aged rats. It has never been tested in humans, and its safety in people is unknown.
What this means: This is a preclinical candidate. Using it now means acting on animal data with no human evidence for benefit or safety.
PMID 24702821 ↗
Part 06 · Cost & access
Where it's available, at what price.
United States
Not approved
No approved product; research compound. No legal consumer medicine.
Grey-market; unregulated
European Union
Not approved
No approved product.
N/A
United Kingdom
Not approved
No approved product.
N/A
Canada
Not approved
No approved product.
N/A
The Peptide Column takes no affiliate commission from any source. P021 has never been tested in humans and is not approved anywhere; material sold to individuals is a research compound, unregulated, with unknown human safety and benefit. We link only to clinician-directed care, never to sellers.
Part 07 · Your appointment
Questions to bring.
01
What is the current state of human evidence for P21?
02
Are there established safety profiles for this peptide in humans?
03
What are the risks of using a neurogenesis-promoting compound without clinical trial data?
04
Are there better-studied alternatives for cognitive support?
References
Every citation, numbered.
Citation list. For our editorial read of each study — including bias flags and quality grades — see the Research log above.
- 01. Rescue of cognitive-aging by a neurogenic/neurotrophic compound (P021) · Neurobiology of Aging, 2014 · PMID 24702821 ↗
- 02. PubMed. P021 preclinical neurotrophic literature