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P-21
Last reviewed: June 11, 2026 by The Peptide Catalog Team
A CNTF-derived adamantylated tetrapeptide (P021) studied in rodent Alzheimer's models for neurogenesis and tau reduction; no human trials exist, sold as a research chemical. P-21 (P021) is a Cerebrolysin-derived peptidergic compound studied in preclinical rodent neurogenesis models; there are no human trials. Research use only.
Overview
Core Benefits
Key AdvantagesThese are educational summaries of commonly discussed effects in wellness/regenerative contexts, not guarantees.
P-21 Results Timeline
ProgressionTimeline is illustrative and non-guaranteed. Outcomes vary and are commonly discussed alongside training, nutrition, sleep, and cycling practices.
How It WorksCNTF-Derived Adamantylated Tetrapeptide — Neurogenic / Neuroprotective (Preclinical Evidence Only; No Human Trials)
Target → Signal → Effect → Outcomes
CNTF-Active-Region Tetrapeptide → BDNF Cascade — Proposed
P-21 (P021) is a synthetic adamantane-modified tetrapeptide — Ac-DGGLAG-NH2(CAS 1246751-68-7) — derived from the active region of ciliary neurotrophic factor (CNTF), residues 148-151. It was developed in Khalid Iqbal's lab by paring Cerebrolysin's neurotrophic activity down to a single defined molecule (Li et al., 2010, PMID 20600002). The adamantane moiety was added to improve metabolic stability and blood-brain-barrier penetration. Although CNTF-derived, the reported procognitive effect runs largely through a BDNF-mediated cascade rather than classical CNTF receptor signaling.
↑BDNF, ↑phospho-CREB, ↓GSK-3β — Preclinical
In rodent and in-vitro models, P021 is reported to enhance dentate-gyrus neurogenesis and synaptic plasticity by inhibiting leukemia inhibitory factor (LIF) signaling and increasing BDNF transcription, with a downstream decrease in GSK-3β activity and increased phospho-CREB (PMID 28368015). Downstream effects in models include reduced tau pathology, preserved synaptic markers, and improved maze learning. All of this is preclinical — no human mechanistic or pharmacokinetic data exists.
Disease-Modifying in Rodent Models — Not Humans
The P-21 evidence base is a coherent, largely single-lab body of rodent work (~2010-2019). Chronic oral P021 reduced age-dependent cognitive decline in aged rats (PMID 24702821), produced disease-modifying effects in 3xTg-AD Alzheimer's mice including a reported survival increase (PMID 25046994), and rescued deficits in a Ts65Dn Down syndrome model (PMID 28368015). It is consistent in direction and clean of integrity flags — but it is rodent disease/aging-model data, not human cognitive-enhancement data. "Disease-modifying in a mouse model" is not "works in people."
Unknown in Humans
There are no human trials of P-21, so there is no evidence base for predicting what a person would notice. Community reports (anecdotal) describe subtle cognitive/mood or focus changes over days to a few weeks, but they are mixed and inconsistent — some describe noticeable effects, others little or nothing, and a subset describe overstimulation or sleep disruption at higher or later-day doses. None of this is placebo-controlled or verified.
What Makes This Peptide Different
P-21's evidence is the opposite kind of limited from Dihexa's: it is clean of retractions and integrity flags, but it is entirely preclinical and mostly from one originating lab, with zero human trials, no human safety, dose, or pharmacokinetic data, and no FDA approval for any indication. Unlike the Dihexa HGF/c-Met oncology discussion, there is no specific cancer-pathway literature tying P-21 to malignancy. It is sold strictly as a research chemical, not for human consumption.
P-21 Vendors
Dosing ProtocolNeurogenesis / Cognition (Research / No Human Data)
Educational reference only. Individual responses vary. Consult healthcare provider before use.
Why This Dosing Protocol
Form and route. Swiss Chems lists P21 as a 5 mg lyophilized vial, so community use involves bacteriostatic-water reconstitution like a standard injectable peptide. Community sources most often describe subcutaneous injection (intranasal is also mentioned), dosed in the morning, in 4-8 week cycles. Note rodent efficacy was shown with oral/peripheral dosing — a route mismatch worth flagging.
Reconstitution Calculator
Dilution math and unit conversions. Prefilled using a common vial size for this peptide.
Open calculatorStorage & Handling
Storage at a glance
Proper storage temperatures, shelf life, reconstitution best practices, and travel tips for lyophilized and reconstituted peptides.
Handling specifics
Educational overview on storage, labeling, and traceability considerations for lab environments. Consult primary literature and vendor documentation for specifics.
- Freezer (-20°C): 1+ year
- Refrigerator (2-8°C): 1-3 months
- Room temperature: 2-3 weeks (emergency only)
- MUST refrigerate at 2-8°C
- 4-week maximum shelf life
- NEVER freeze after reconstitution
- Use bacteriostatic water for multi-dose
FAQ
What is P-21 (P021)?
A synthetic adamantane-modified tetrapeptide (Ac-DGGLAG-NH2; CAS 1246751-68-7) derived from the active region of ciliary neurotrophic factor (CNTF). It was developed in Khalid Iqbal's lab by paring Cerebrolysin's neurotrophic activity down to a single defined molecule. It is studied for neurogenesis and tau reduction in rodent Alzheimer's models and is sold as a research chemical, not for human consumption.
Does P-21 have human clinical trials?
No. There are no published human clinical trials of P-21, and no trials are registered on ClinicalTrials.gov. All evidence is preclinical (rodent and in-vitro). There is no human safety, dose, or pharmacokinetic data. No retractions or integrity flags were found in the P-21 literature — a genuine difference from Dihexa, whose foundational papers were retracted.
Is there an established dose for P-21?
There is no clinically-established human dose — no human trial has defined one. The figures community and vendor sources actually use cluster around 500 mcg to 1 mg once daily (broader cited range ~100 mcg-2 mg/day), typically subcutaneous or intranasal. Those numbers are anecdotal and vendor-derived, not trial-validated.
What does the preclinical research show?
In rodent models, chronic P021 was reported to enhance neurogenesis, increase BDNF, reduce tau pathology, preserve synaptic markers, and improve maze learning — in aged rats (PMID 24702821), a 3xTg-AD Alzheimer's model (PMID 25046994), and a Ts65Dn Down syndrome model (PMID 28368015). These are animal disease/aging models, not human cognitive-enhancement data, and the work is largely from one originating lab.
What side effects are reported?
There is no human safety data. The most consistent anecdotal complaint is sleep disruption or overstimulation, especially at higher doses or evening dosing — the basis for the common "dose in the morning" community advice. Headache and irritability are mentioned occasionally. Reports are inconsistent, and rodent toxicology is not comprehensively published. Decisions about a compound with no human safety profile are matters for a licensed physician.
How long does reconstituted peptide last?
Once mixed with bacteriostatic water, peptides remain stable for up to 4 weeks when refrigerated at 2-8°C (36-46°F). Unopened powder can last 1+ year in the freezer. Get our complete Storage & Travel Guide.
Is this peptide legal to purchase?
Peptides sold "for research purposes only" are legal to purchase in the US, but are not FDA-approved for human use outside of specific medical applications. Always consult a healthcare provider before use.
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P-21 Research Articles
P-21 Dosage: What the Community Reports
P-21 has no trial-set dose. See the 500 mcg-1 mg figure community sources actually use, the route mismatch, and the all-rodent evidence behind it.
side-effectsP-21 Side Effects: The No-Human-Data Reality
P-21 has zero human safety data — every figure is preclinical or anecdotal. The sleep-disruption signal and theoretical cautions, graded by source.
resultsP-21 Timeline: What the Evidence Shows
No human trial sets a P-21 timeline. Here's the gap between rodent chronic-dosing data and community-reported onset, each clearly labeled.
reconstitutionP-21 Reconstitution: 5mg Vial Bac Water Math
P-21 ships as a 5mg lyophilized vial with no validated human dose. Here's the bac-water math community sources use for the ~500mcg-1mg subQ range.
Disclosure: we may earn affiliate commission from qualifying purchases. Educational information only — not medical advice.