P21 (P021) protocol

Standard

Weeks 1–6

12.5–25u (SubQ)

250–500 mcg SubQ or 500 mcg–1 mg intranasal · Daily

Intranasal is the common route. Effects are cumulative.

Off

2–4 weeks

Cycle 4–8 weeks on / 2–4 weeks off.

Phase	How often	Dose	Units	Notes
Weeks 1–6	Daily	250–500 mcg SubQ or 500 mcg–1 mg intranasal	12.5–25u (SubQ)	Intranasal is the common route. Effects are cumulative.
Off	2–4 weeks	–	–	Cycle 4–8 weeks on / 2–4 weeks off.

Units at 2 mg/mL. Caution: no completed human trials, doses are user/animal-derived.

Cycle & timing

Cycle: 4–8 weeks on / 2–4 weeks off.

Timing: Daytime; neurogenic effects build over weeks, do not expect immediate changes. Route: intranasal gives direct nose-to-brain delivery; SubQ also used.

Where: Intranasal spray (common) or SubQ abdomen. Rotate.

What to expect

Gradual memory/cognitive support over weeks if effective; cumulative. Strongest rationale is in age-related cognitive decline (animal models).

How much to buy

For 6-wk @ 250 mcg/day SubQ; more if intranasal mg-dosing:

2

× 5mg vials

Men & women

Unisex experimental neurogenic peptide, animal data only, no sex-specific dosing. Avoid in pregnancy.

Dilution calculator

Set to the guide's typical mix for P21 (P021). Change anything to see where to draw.

Vial size

BAC water added

Dose you want

Draw to

12.5u

Volume

0.13 mL

Strength

2 mg/mL

Doses per vial

20

Assumes a U-100 insulin syringe (100 units = 1 mL). Double-check against the compound's page before you draw.

Recommended mixes

Vial	Water	Strength
5 mg	2.5 mL	2 mg/mL

5 mg: 1 unit = 0.02 mg (20 mcg). For nasal use, transfer to a metered spray bottle.

Storage

PowderFreeze-dried: -4°F.
MixedReconstituted: 36–46°F, up to 4 weeks.

Don't use if: Pregnancy and lactation · Active malignancy (theoretical growth-factor concern) · Hypersensitivity to the peptide

Stop if you notice

Persistent nasal irritation (intranasal) or headache
Any unexpected systemic reaction
Pregnancy

Side effects

Generally mild in reports, nasal irritation (intranasal), mild headache. Human profile not formally characterized.

Drug interactions

No well-characterized interactions. Stacks with other nootropic peptides, unproven combinations.

Labs

None established; cognitive tracking if used for that purpose

What these labs mean →

Warnings

Neurotrophic/growth signaling, theoretical caution with malignancy. Quality varies, request a COA. Effects are cumulative, not an acute nootropic.

Patient education

Cumulative neurogenic peptide, give it weeks, not days. Intranasal delivery targets the brain directly. Request a COA; source quality matters.

These apply on top of the universal safety rules.

Pairs well with

Semax / Selank

cognition + mood

Semax Selank

Cerebrolysin

neurotrophic synergy

Cerebrolysin

NAD+

Avoid with

Active malignancy

growth-factor signaling, theoretical

Pregnancy

Can P21 (P021) + Semax share a syringe?

Can share a syringe. Both are water-based. Combine them if you dose on the same schedule and site.

What it does

No completed human trials.

P21 (P021) is a CNTF-derived neurotrophic tetrapeptide mimetic. It promotes neurogenesis, raises BDNF, inhibits leptin-pathway-linked tau pathology, and shows disease-modifying effects in Alzheimer's models. Intranasal delivery exploits nose-to-brain transport, bypassing the blood-brain barrier.

References

researchdosing peptidedosages PubMed thepeptidereport

From the guide, page 72.