P21 5mg Dosage & Mixing Guide

What is P21?

P21 (also written P021, research code GLXC-21260) is a small synthetic neurogenic and neurotrophic peptide, structure Ac-DGGL(A)G-NH2, molecular weight roughly 578.7. It was built by epitope-mapping the biologically active region of human ciliary neurotrophic factor (CNTF) down to a four-residue core, then adding an adamantylated glycine at the C-terminus to raise lipophilicity, slow exopeptidase degradation, and improve blood-brain barrier passage. The work came out of Khalid Iqbal’s laboratory at the New York State Institute for Basic Research in Developmental Disabilities.

Worth clearing up one thing, because the peptide web muddles it: P21 is CNTF-derived, not Cerebrolysin-derived. The confusion is understandable — EVER Neuro Pharma, the company behind Cerebrolysin, collaborated on the compound’s stability characterisation — but P21 is a defined single molecule, while Cerebrolysin is a porcine brain-derived peptide mixture. They are not the same lineage. Within the catalogue it sits alongside Semax, Selank and Pinealon as a cognitive-category research peptide.

Reconstitution

P21 reconstitutes with bacteriostatic water. Draw 2mL down the inside wall of the vial, swirl gently until fully dissolved, and refrigerate. Do not shake.

Quick Reference

Reconstitution Guide

Materials Needed

• P21 5mg lyophilized vial
• Bacteriostatic water (BAC water)
• Insulin syringes (U-100, 29-31 gauge)
• Alcohol swabs
• Sharps container

Step-by-Step Instructions

1. Prepare workspace — Clean environment, gather materials, thorough handwashing.
2. Clean vial stoppers — Wipe both vials with alcohol swabs. Allow complete drying.
3. Draw BAC water — Draw 2mL bacteriostatic water using a sterile syringe.
4. Add to peptide — Inject slowly down the inside wall of the vial. Do not spray directly onto the powder.
5. Dissolve — Allow a few minutes for complete dissolution. Gentle swirl only — no shaking.
6. Verify — Solution should be clear.
7. Label and store — Note reconstitution date. Refrigerate immediately.

Dosage Protocol

Concentration Calculations

With 5mg peptide in 2mL BAC water:

• Concentration: 5mg ÷ 2mL = 2.50mg/mL (2500mcg/mL)
• Per unit (U-100 syringe): 2.50 × 1000 ÷ 100 = 25mcg per unit

Run your exact vial and water combination through the peptide reconstitution calculator to rebuild this table for your setup.

Common Dose Calculations

The figures above are arithmetic, not recommendations. No human dosing study for P21 exists, so there is no established research dose to anchor to — the rodent work used dietary administration, which does not convert cleanly to a measured volume in a syringe.

Research Considerations

Mechanism

P21 appears to work upstream of the neurotrophin cascade rather than acting as a direct receptor agonist. The proposed sequence is competitive interference with LIF signalling, followed by upregulation of BDNF and its receptor TrkB, CREB activation, and PI3K/AKT signalling that inactivates GSK-3β. In rodent models that translated into increased hippocampal neurogenesis in the dentate gyrus, restored dendritic and synaptic markers, and reduced tau hyperphosphorylation.

The evidence base is worth stating plainly: it is entirely preclinical and largely from one research group. Published work covers 3xTg-AD mice, the Ts65Dn Down syndrome model, aged rats, and a traumatic brain injury model. There are no human trials, no human pharmacokinetics, and no measured elimination half-life in any species — the “over 3 hours” figure circulating on vendor pages traces back to an ex-vivo plasma stability incubation, not to a dosing study.

Sourcing for Research

Source from verified suppliers that provide third-party testing and certificates of analysis (COA) for each batch. The adamantylglycine residue makes P21 harder to synthesise than a plain tetrapeptide, so mass-spec identity confirmation matters more here than usual. Compare purity documentation, shipping conditions, and batch traceability before purchasing research materials.

Storage Requirements

Lyophilized (Powder)

• Temperature: -20°C or colder
• Duration: 2+ years
• Conditions: Dry, dark, protected from moisture

Reconstituted

• Temperature: 2-8°C (refrigerated)
• Duration: 2-3 weeks
• Conditions: Protected from light, never freeze

Safety Considerations

• P21 is a research compound
• Not approved for any indication in any jurisdiction
• Research use only — not for human consumption
• Use sterile technique; never reuse needles or syringes

Scientific References

1. Li B, Wanka L, Blanchard J, et al. Neurotrophic peptides incorporating adamantane improve learning and memory, promote neurogenesis and synaptic plasticity in mice. FEBS Letters. 2010;584(15):3359-3365.
2. Kazim SF, Blanchard J, Dai CL, et al. Disease modifying effect of chronic oral treatment with a neurotrophic peptidergic compound in a triple transgenic mouse model of Alzheimer’s disease. Neurobiology of Disease. 2014;71:110-130.
3. Bolognin S, Buffelli M, Puoliväli J, Iqbal K. Rescue of cognitive-aging by administration of a neurogenic and/or neurotrophic compound. Neurobiology of Aging. 2014;35(9):2134-2146.
4. Kazim SF, Iqbal K. Neurotrophic factor small-molecule mimetics mediated neuroregeneration and synaptic repair: emerging therapeutic modality for Alzheimer’s disease. Molecular Neurodegeneration. 2016;11:50.

Last updated: 2026-07-21.

Disclaimer: This information is for educational and research purposes only. P21 is a research compound and is not approved for any use. Research-grade peptides are not intended for human consumption. Always follow applicable laws and institutional guidelines.