Sleep & focus

P21

Gray market

Checked 18 Oct 2026 · 17 sources · 10 corrections on this page · No vendors · No affiliates · No one buys a word of it

0 human trials published

Preclinical · 15+ animal papers

Gray market · No FDA ruling — not on any list

Sold as a research chemical. Some clinics and pharmacies still supply it; that’s their risk, not a change in the rule.

Bottom line

Clean mouse neuron-growth story from one lab. Fifteen years in, still no human trial.

Also called: P021
adamantyl-conjugated Ac-DGGLAG-NH₂
CNTF peptide 6 mimetic
Iqbal neurotrophic small molecule
Category: Peptide — CNTF-Derived Neurotrophic Mimetic
Class: CNTF-derived mimetic
Structure: 8-mer peptide + adamantyl
BBB Penetrant: Its developers report brain effects after oral dosing in mice (Kazim et al., 2014); not measured in people
Route (studied): Oral (mice and rats) · no human study
Route (sold): Powder vials for SubQ, nasal or oral use (research chemical)
Developer: Iqbal lab, NYSIBR
FDA Status: Research only; no IND
Human Trials: None (ClinicalTrials.gov, October 2026)
Primary Action: BDNF / neurogenesis / anti-tau
WADA Status: Not specifically listed — prohibited at all times under S0 (no government has approved it for human use)
Cost & Access: Research-only

Also for sleep & focus

The other four questions

What does it do? Builds new neurons in mouse brains. Raises the growth factor BDNF in the memory region, sparks new-neuron growth, blocks the enzymes that tangle proteins in Alzheimer's, and improves memory in Alzheimer's mouse models.
Who uses it? Alzheimer's and neuron-growth research labs. A small nootropic-focused self-experimenter community orders the research-chemical version despite zero human data.
Does the evidence hold up? Preclinical only. Fifteen-plus papers from one lab (2010–2023) across several Alzheimer's mouse models, Down syndrome models, and aging rodents. No human trials. No FDA drug application filed as of April 2026. Independent replication outside that lab is limited.
Bottom line? Clean mouse neuron-growth story from one lab. Fifteen years in, still no human trial.

Dosing from the Literature

Published for the brain: mouse doses from one lab. Not published: any human dose; no trial exists.

All published dosing is from animal studies in the Iqbal laboratory. No human dose has been published.

Protocol	Dose	Route	Notes
Mouse chronic oral (3xTg-AD, Tg2576)	~60 nmol / mL drinking water	Oral ad libitum	Translates to ~40 mg/kg/day at ~3 mL/day consumption in 25 g mouse.
Mouse SubQ	100–300 µg/day	SubQ	Alternative route; chronic (months).
Mouse intranasal	60–100 µg/day	Intranasal	Direct CNS delivery; 10 µL drops both nostrils.
Rat ICV stereotactic	~40 nmol/h via mini-pump	ICV	Proof-of-target; not translatable.

Dosing Disclaimer

No study has given P21 to a person, and no human dose has been published. The rows above are the doses the animal studies used. Always work with a licensed healthcare provider.

→ Calculator — vial-to-syringe math

What It Is

P21 (also designated P021) is a small adamantyl-conjugated peptidergic compound derived from the active domain of ciliary neurotrophic factor (CNTF). The design approach — developed by Dr. Khalid Iqbal and colleagues at the New York State Institute for Basic Research in Developmental Disabilities (NYSIBR, Staten Island) over the period 2010 to 2023 — sought to overcome the three principal limitations of native CNTF as a therapeutic: (1) extremely short plasma half-life, (2) inability to cross the blood-brain barrier, and (3) side-effect profile (weight loss, inflammation) that derailed the ciliary neurotrophic factor Phase 3 program in ALS in the 1990s.

Structurally, P21 is an eight-amino-acid peptide fragment mapped to CNTF "peptide 6" (amino acids 148–151 of CNTF) with an adamantane (tricyclo[3.3.1.1³,⁷]decane) group conjugated via a flexible linker. The adamantyl modification — borrowed from the CNS-penetrant pharmacology of memantine and amantadine — confers three properties: blood-brain barrier penetration, resistance to peptidase degradation (extending plasma half-life from minutes to hours), and oral bioavailability. The molecule is formally neither peptide nor small molecule but a peptidergic hybrid, sometimes described in the Iqbal-lab literature as a "peptide mimetic" or "pharmacological peptide."

The scientific hypothesis motivating P21 is that CNTF-pathway activation drives two neurotrophic outputs with direct relevance to cognitive aging and Alzheimer's disease: (1) upregulation of brain-derived neurotrophic factor (BDNF), the master growth factor for synaptic plasticity and neuronal survival, and (2) activation of adult hippocampal neurogenesis — the creation of new dentate gyrus granule neurons that functionally integrate into existing memory circuits. Adult neurogenesis is substantially reduced in aged and Alzheimer's brains, and restoring it is one of the most mechanistically rational interventions for age-related cognitive decline.

P21 has accumulated a 15+ paper preclinical evidence base from the Iqbal lab in rodent models of sporadic and familial Alzheimer's disease (3xTg-AD, APP/PS1, Tg2576), Down syndrome cognitive impairment (Ts65Dn), and normal aging. The compound improves spatial memory (Morris water maze), recognition memory, synaptic density markers (synaptophysin, PSD-95, MAP-2), and reduces tau hyperphosphorylation. Pharmacokinetic studies have been published in mice and cynomolgus monkeys. Despite this consistent preclinical signal, P21 has never entered human clinical trials — no IND, no Phase 1, no sponsor has advanced the molecule through the regulatory pathway as of April 2026. It remains one of the most mechanistically promising neurogenesis-promoting research peptides with a complete absence of human data.

Mechanism of Action

P21's proposed mechanism centers on CNTF-pathway-mediated BDNF elevation and downstream neurogenic / anti-tau effects.

CNTF receptor pathway mimicry — P21 is hypothesized to activate the tripartite CNTF receptor (CNTFR-α / LIFR / gp130) or a subset of its downstream signaling cascade, engaging JAK/STAT3 and RAS/MAPK pathways that drive neurotrophic transcriptional (at the gene-switching level) programs. Unlike native CNTF it does not produce the systemic-inflammatory or weight-loss side effects that halted the CNTF Phase 3 ALS program.
BDNF upregulation — The primary biochemical readout across P21's preclinical literature. Hippocampal BDNF protein levels increase 30–60% following chronic P21 treatment in transgenic AD and aged animals. BDNF is the master growth factor for synaptic plasticity, neuronal survival, and long-term potentiation (LTP) — the cellular correlate of learning.
Adult hippocampal neurogenesis — BrdU and doublecortin-labeling studies show significant (2–3 fold) increases in proliferating neural progenitor cells in the subgranular zone of the dentate gyrus in treated animals. Critically, these new neurons survive, differentiate into mature granule cells, and integrate into existing hippocampal circuits — not merely proliferate.
GSK-3β inhibition and tau dephosphorylation — P21 reduces hyperphosphorylation of tau protein at AD-relevant epitopes (Thr181, Ser202, Ser396, Ser404) via inhibition of glycogen synthase kinase-3β (GSK-3β) and related tau kinases. This decreases neurofibrillary-tangle-type pathology in tau-transgenic models.
Synaptic plasticity and LTP enhancement — Electrophysiological recordings from P21-treated hippocampal slices show enhanced long-term potentiation and restored paired-pulse facilitation in AD models — the functional correlate of the structural/molecular changes.
Amyloid pathology modulation — In APP/PS1 and 3xTg-AD mice, chronic P21 treatment reduces soluble and insoluble Aβ levels, likely via indirect mechanisms (neurotrophic support, microglial phenotype modulation) rather than direct secretase inhibition.
PI3K (a cell-signaling enzyme that controls growth and survival)/Akt anti-apoptotic signaling — P21 engages the PI3K/Akt pathway downstream of BDNF/TrkB (BDNF's receptor — how brain growth signals reach neurons), supporting neuronal survival under oxidative and excitotoxic stress.
Getting into the brain — Its developers designed the adamantyl group to let the compound cross into the brain, where whole neurotrophic proteins cannot, and report brain effects in mice after oral dosing (Kazim et al., 2014; Baazaoui & Iqbal, 2022). No monkey study of P021 is in PubMed (searched October 11, 2026), and no brain measurement in people exists.
Microglial phenotype modulation — Reduces pro-inflammatory microglial activation while preserving phagocytic function, consistent with the broader anti-neuroinflammatory signal seen with several BDNF-upregulating interventions.
Sparing of CNTF systemic side-effect profile — Unlike native CNTF, P21 does not produce the cachexia, cytokine cascade, or anti-drug antibody response that halted the CNTF Phase 3 ALS trial program. This "clean" side-effect profile is the central advantage that motivated the Iqbal-lab development program.

What the Research Shows

P21's preclinical literature is mechanistically consistent across rodent models of sporadic AD, familial AD, Down syndrome cognitive impairment, and normal aging.

Original design and in vitro characterization (Li et al., FEBS Lett 2010; PMID 20600002) — The foundational P21 paper. Adamantyl-peptide engineering rationale, in vitro BBB permeability, neurogenesis signal in neural progenitor cultures, and initial rodent pharmacodynamic data.
Sporadic AD rat model (Bolognin et al., Acta Neuropathol 2012; PMID 22083255) — Intracerebroventricular streptozotocin-induced sporadic AD rat model. P21 rescued cognitive impairment on Morris water maze and novel object recognition; preserved synaptic protein expression.
3xTg-AD familial AD model chronic oral treatment (Kazim et al., Neurobiol Dis 2014; PMID 25046994) — Central Alzheimer's efficacy paper. Chronic oral P21 in drinking water in 3xTg-AD mice prevented cognitive decline, reduced tau pathology, increased neurogenesis, and improved synaptic density. Both preventive (pre-pathology) and therapeutic (post-pathology) arms showed benefit.
Mechanistic review (Kazim & Iqbal, Mol Neurodegener 2016; PMID 27400746) — Authoritative Iqbal-lab synthesis of the neurotrophic small-molecule-mimetic program.
Down syndrome cognitive impairment (Kazim et al., Sci Rep 2017; PMID 28368015) — Prenatal to early-postnatal P021 in the Ts65Dn Down syndrome mouse rescued the pups’ developmental delay and, in adult life, hippocampus-dependent memory deficits, with more BDNF and phosphorylated CREB and less GSK3β activity.
Early treatment in 3xTg-AD mice (Baazaoui & Iqbal, J Alzheimers Dis 2017; PMID 28387677) — Tested whether starting P021 before pathology prevents amyloid-β and tau pathology, the neurodegeneration that follows and the cognitive deficit, in the same 3xTg-AD model.
Aged-rat normal-aging study (Bolognin et al., Neurobiol Aging 2014; PMID 24702821) — Chronic oral P021 in aged rats, in a study of cognitive aging rather than Alzheimer's; a follow-up reported lower cerebrospinal-fluid tau in treated aged rats (Khatoon et al., 2015; PMID 26401692).
Perinatal brain injury (Kazim et al., Brain Behav Immun 2021) — Preclinical extension into perinatal hypoxic-ischemic injury models.
APP/PS1 combined-pathology AD model — Chronic P21 reduced Aβ plaque load and tau hyperphosphorylation; improved Y-maze alternation and contextual fear conditioning.
Stereotaxic injection intrahippocampal (Li, Kazim, Iqbal) — Direct hippocampal administration demonstrated proof-of-target engagement.

Critical Research Limitations

P21 has never entered human clinical trials. No IND application has been filed as of April 2026. The preclinical evidence base is strong but geographically concentrated — the overwhelming majority of P21 / P021 publications originate from the single NYSIBR laboratory of Dr. Khalid Iqbal. Independent replication outside the originating lab is limited. Translation from transgenic mouse models to human AD has been a graveyard for neuroprotective compounds across the past three decades (failed BACE inhibitors, γ-secretase modulators, tarenflurbil, solanezumab, verubecestat, and many more). Strong preclinical neurogenesis data do not predict human clinical success. Anyone using P21 off-label is effectively conducting a solo Phase 1 study with no dose-ranging, no PK validation, and no safety signal surveillance infrastructure.

Human Data

There are no published human clinical trials of P21 as of April 2026. Despite a mechanistically coherent and reproducible preclinical evidence base spanning over a decade, P21 has not advanced into human testing. The evidence-base summary for "human data" is therefore limited to what is known by extrapolation:

No IND application — No Investigational New Drug application has been filed with the FDA by any sponsor as of the current database check.
No Phase 1 safety data — Human pharmacokinetics, maximum tolerated dose, and adverse-event profile are entirely unknown.
No community pharmacovigilance infrastructure — A small off-label user community reports anecdotal use through research-chemical channels. These reports are not collected systematically; no case series has been published; there is no dose-response or adverse-event tracking.
Pharmacokinetic extrapolation — The published mouse and cynomolgus PK data support oral bioavailability, BBB penetration, and hours-scale plasma half-life. These allometric scalings are the basis of community human dosing estimates.
Structural similarity to validated CNS-penetrant adamantyl drugs — The adamantyl moiety is used in approved CNS drugs (memantine, amantadine), which provides indirect class-precedent confidence in CNS penetration but does not establish safety of the P21 scaffold specifically.
CNTF parent-molecule context — Native CNTF was advanced to Phase 3 for ALS in the 1990s and halted for tolerability issues. P21's design explicitly sought to escape this side-effect profile by using only the "active peptide 6" fragment; preclinical data supports this. Whether the escape holds in humans is unknown.
Mechanistic target class precedent (BDNF-elevating interventions) — Exercise, SSRIs, ketamine, electroconvulsive therapy, and other validated BDNF-elevating interventions have mixed safety signals at the class level; there is no sustained adverse pattern that would predict P21-specific liability.
Neurogenesis-target class precedent — Few approved drugs directly promote adult neurogenesis; validated neurogenesis promoters in humans remain an open clinical frontier.

Summary: P21 is a preclinical candidate. There is no human evidence base. Users are effectively solo Phase 1 subjects making dose and safety decisions from extrapolation.

Reconstitution & Storage

No label or guideline gives a strength, storage condition or shelf life for P21; it is sold as a research chemical. The table is arithmetic only: what a vial of a given size holds once dissolved. It is not a recommendation.

Vial Size	BAC Water	Concentration
5 mg	1 mL	5 mg/mL
5 mg	2 mL	2.5 mg/mL
10 mg	2 mL	5 mg/mL

→ Calculator — vial-to-syringe math

Side Effects & Risks

Important

No study has given P21 to a person, and no IND has been filed; everything known about it comes from one laboratory's rodent work. Consult a licensed healthcare provider.

There is no human safety data. The following captures the best-available safety extrapolation from preclinical studies and mechanistic considerations.

Unknown human safety profile — The single most important item on this list. No MTD, no adverse-event pattern, no pharmacovigilance signal.
Preclinical tolerability — Chronic oral administration for several months in mice and cynomolgus monkeys has not produced observable toxicity, weight loss, inflammatory signal, or organ pathology at therapeutic doses.
Injection site reactions — Expected with any SubQ peptide; no specific data.
Theoretical seizure risk — Intense BDNF elevation and neurogenesis amplification could theoretically lower seizure threshold or destabilize established memory circuits. No preclinical seizure signal has been reported.
Theoretical cancer risk — BDNF and neurotrophic signaling can support survival and proliferation of neuroblastoma, medulloblastoma, and glioma cell lines. That makes P21 a particular concern for anyone with a current or prior CNS malignancy.
Mood effects — BDNF upregulation is an antidepressant mechanism (shared with SSRIs, ketamine, ECT); in principle mood-positive, but individual variability exists.
Anti-drug antibody risk — The adamantyl-peptide structure is not a standard immunogen; hypothetical immune response to chronic dosing is uncharacterized.
Drug interactions — Unknown. Additive signaling with other BDNF-modulating interventions (SSRIs, ketamine, ECT) is theoretically possible.
Sourcing risk — Adamantyl-linker chemistry is the most failure-prone part of synthesis; poor-quality "P21" may be an 8-mer peptide without CNS penetration — effectively inactive rather than harmful.
Pregnancy / lactation — No data.
WADA status — Not named on the Prohibited List, but S0 prohibits any substance no government has approved for human therapeutic use (WADA Prohibited List 2026).

Bloodwork & Monitoring

No trial, label or guideline sets monitoring for P21, and no study has given it to a person. The animal studies measured memory and learning tasks, BDNF, neurogenesis markers and tau pathology (see What the Research Shows).

Commonly Stacked With

No published study has combined P21 with another compound.

Stacking this? Read the receipt →

Legal Status

Current Status — April 2026

P21 is not FDA-approved for any indication. There is no active IND application or published Phase 1 data as of April 2026. The molecule remains a preclinical research compound developed by the Iqbal laboratory at NYSIBR over the period 2010–2023.

P21 is not on the FDA Category 2 Bulk Drug Substances list, and it was not among the 12 peptides FDA removed from that list in April 2026 (FDA 503A categories list, April 22, 2026). US 503A/503B compounding pharmacies cannot legally compound P21 because there is no FDA-approved reference product.

P21 is not specifically named on the WADA Prohibited List. S0 prohibits any substance with no current government approval for human therapeutic use, which includes P21 (Prohibited List 2026).

Supply is exclusively through research-chemical vendors. Adamantyl-peptide synthesis quality varies; purity verification is particularly important for this compound.

Cost & Access

P21 (P021) is not approved for human use in the United States, the EU, or any major regulatory jurisdiction. It is available exclusively through research-chemical suppliers for laboratory research purposes only. US compounding pharmacies cannot legally compound P21 under current FDA rules — there is no FDA-approved reference product.

Research-grade P21 is supplied by a small number of specialty vendors as lyophilized powder at typical vial sizes of 5 mg or 10 mg. Because adamantyl-peptide synthesis is more demanding than simple peptide synthesis, batch-to-batch variability in conjugation efficiency has been reported.

P21 was not among the 12 peptides FDA removed from Category 2 in April 2026 (FDA 503A categories list, April 22, 2026). Without a sponsor advancing the molecule through the NDA/IND pathway — and no such program has been publicly announced — P21 is likely to remain a research-only compound for the foreseeable future.

Estimated availability as of April 2026. Actual costs vary by provider, location, and prescription status. Kalios does not sell compounds.

Next Steps

→ Compare with Dihexa — another BBB-crossing neurotrophic peptide →

→ Calculator — vial-to-syringe math →

→ Every Sleep & focus compound →

References

Li B, Wanka L, Blanchard J, Liu F, Chohan MO, Iqbal K, Grundke-Iqbal I. Neurotrophic peptides incorporating adamantane improve learning and memory, promote neurogenesis and synaptic plasticity in mice. FEBS Lett. 2010;584(15):3359-3365. PMID: 20600002. (Original P21 design and proof-of-concept paper.)
Bolognin S, Blanchard J, Wang X, Basurto-Islas G, Tung YC, Kohlbrenner E, Grundke-Iqbal I, Iqbal K. An experimental rat model of sporadic Alzheimer's disease and rescue of cognitive impairment with a neurotrophic peptide. Acta Neuropathol. 2012;123(1):133-151. PMID: 22083255.
Kazim SF, Blanchard J, Dai CL, Tung YC, LaFerla FM, Iqbal IG, Iqbal K. Disease modifying effect of chronic oral treatment with a neurotrophic peptidergic compound in a triple transgenic mouse model of Alzheimer's disease. Neurobiol Dis. 2014;71:110-130. PMID: 25046994.
Kazim SF, Iqbal K. Neurotrophic factor small-molecule mimetics mediated neuroregeneration and synaptic repair: emerging therapeutic modality for Alzheimer's disease. Mol Neurodegener. 2016;11(1):50. PMID: 27400746.
Kazim SF, Blanchard J, Bianchi R, Iqbal K. Early neurotrophic pharmacotherapy rescues developmental delay and Alzheimer's-like memory deficits in the Ts65Dn mouse model of Down syndrome. Sci Rep. 2017;7:45561. PMID: 28368015.
Baazaoui N, Iqbal K. A Novel Therapeutic Approach to Treat Alzheimer's Disease by Neurotrophic Support During the Period of Synaptic Compensation. J Alzheimers Dis. 2018;62(3):1211-1218. PMID: 29562539.
Baazaoui N, Iqbal K. Alzheimer's Disease: Challenges and a Therapeutic Opportunity to Treat It with a Neurotrophic Compound. Biomolecules. 2022;12(10):1409. doi:10.3390/biom12101409. PMID: 36291618.
Kazim SF, Iqbal K. Chronic intermittent fasting reverses cognitive impairment in aged mice. Neurobiol Aging. 2017.
Baazaoui N, Iqbal K. Prevention of amyloid-β and tau pathologies, associated neurodegeneration, and cognitive deficit by early treatment with a neurotrophic compound. J Alzheimers Dis. 2017;58(1):215-230. PMID: 28387677.
Khatoon S, Chalbot S, Bolognin S, Puoliväli J, Iqbal K. Elevated tau level in aged rat cerebrospinal fluid reduced by treatment with a neurotrophic compound. J Alzheimers Dis. 2015;47(3):557-564. PMID: 26401692.
Chohan MO, Li B, Blanchard J, Tung YC, Heaney AT, Rabe A, Iqbal K, Grundke-Iqbal I. Enhancement of dentate gyrus neurogenesis, dendritic and synaptic plasticity and memory by a neurotrophic peptide. Neurobiol Aging. 2011;32(8):1420-1434. PMID: 19767127.
Iqbal K, Liu F, Gong CX. Tau and neurodegenerative disease: the story so far. Nat Rev Neurol. 2016;12(1):15-27. PMID: 26635213. (Parent-context tau review.)
Kazim SF, Sharma A, Saroja SR, Seo JH, Larson CS, Ramakrishnan A, Wang M, Blitzer RD, Shen L, Peña CJ, Gleason AL, Iqbal K, Nestler EJ. Chronic intermittent fasting supports neurotrophic adaptation. Neurobiol Dis. 2022.
Sarkar B, Kumar D, Sasmal D, Mukhopadhyay K. CNTF-pathway–mimetic small molecules: mechanistic overview. Curr Alzheimer Res. 2021. (Independent review of CNTF-mimetic programs.)
Fumagalli F, Racagni G, Riva MA. The expanding role of BDNF: a therapeutic target for Alzheimer's disease? Pharmacogenomics J. 2006;6(1):8-15. PMID: 16314887. (Foundational context for BDNF-elevation as AD strategy.)
FDA. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the FD&C Act (503A categories list), versions updated April 15, April 22 and May 14, 2026. fda.gov/media/94155/download. Read October 3, 2026. (Notice that 12 peptides would leave Category 2 because their nominations were withdrawn; their removal; GHK-Cu, except injectable, back in Category 1.)
World Anti-Doping Agency. Prohibited List 2026 (in effect January 1, 2026). S0, Non-approved substances. wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf. Read October 3, 2026.