Peptide Association LLC is a for-profit company. We receive compensation from the clinical providers listed on this site. We are not an accrediting body, a licensing board, or a government-affiliated organization. See exactly how we make money.
P21 (Peptide)
Overview
A small synthetic peptide derived from the active region of ciliary neurotrophic factor (CNTF) designed to promote neurogenesis and synaptic plasticity. P21 is a tetrapeptide that crosses the blood-brain barrier and enhances dentate gyrus neurogenesis by increasing BDNF expression.
Mechanism of Action
Unlike full-length CNTF, P21 does not activate the JAK-STAT pathway or produce the anorectic and immunogenic effects of the parent protein.
Research Summary & Key Findings
Preclinical studies in Alzheimer's disease mouse models showed significant improvements in spatial learning and memory, correlated with increased hippocampal neurogenesis and synaptic density (Bolognin et al., Neurobiol Dis, 2014). Reduced tau hyperphosphorylation and neurofibrillary pathology in transgenic mice. Currently in preclinical development with no human clinical trials completed.
Clinical Status
P21 (Peptide) is in the research phase with limited clinical data in humans. Current evidence is primarily derived from preclinical (animal or in vitro) studies.
Administration Routes
References
Primary literature
- PubMed: "P21"
Peer-reviewed literature indexed by the National Library of Medicine.
- ClinicalTrials.gov: "P21"
Registered interventional and observational studies, including status and phase.
- PubChem: "P21"
Chemical structure, molecular properties, and bioactivity data.
Study-level citations for this compound are being verified against the primary sources before publication. The database queries above return the current indexed literature in the meantime.
Related Peptides in Cognitive
Semax
InvestigationalA synthetic heptapeptide analog of the ACTH(4-7) fragment (Met-Glu-His-Phe-Pro-Gly-Pro) with nootropic and neuroprotecti...
View detailsSelank
InvestigationalA synthetic analog of the endogenous tetrapeptide tuftsin (Thr-Lys-Pro-Arg) with an added Pro-Gly-Pro sequence for stabi...
View detailsCerebrolysin
InvestigationalA porcine brain-derived peptide preparation consisting of low-molecular-weight neuropeptides and free amino acids that m...
View detailsDihexa
Research PhaseDihexa is a small synthetic hexapeptide derived from angiotensin IV, designed to bind and potentiate hepatocyte growth f...
View detailsNo lawful pathway today
P21 (Peptide) is not FDA-approved and does not currently have a lawful prescription or compounding pathway in the United States, so there is nothing for us to sell you here and no consultation to book. That can change: eight peptides moved back to a lawful pathway in February 2026.
Tell me if the status changes
One email, only if this compound's regulatory standing actually moves. Not a newsletter, not a sales sequence.
Join the Association
Access exclusive peptide protocols, provider resources, and community support.
List Your PracticeDisclaimer: This information is provided for educational and research purposes only. It is not intended as medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting any peptide therapy. The Peptide Association does not endorse or recommend any specific treatment protocol. See our editorial policy for how this content is produced and reviewed.