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№ 052

P-21

Synthetic ciliary neurotrophic factor (CNTF)-mimetic peptide. Targets neurogenesis. Pre-clinical / early research compound.

Nootropic
Evidence: Anecdotal

P-21: Synthetic ciliary neurotrophic factor (CNTF)-mimetic peptide. Targets neurogenesis. Pre-clinical / early research compound. P-21 is a synthetic peptide that mimics CNTF (ciliary neurotrophic factor).

FDA ⓘ
Not approved
WADA
Not banned
Typical dose
No standardized human dose
Half-life ⓘ
~hours
Route ⓘ
Subcutaneous
Schedule
Daily
In plain English

P-21 is a synthetic peptide that mimics CNTF (ciliary neurotrophic factor). Targets neurogenesis pathways. Pre-clinical research compound, no human dosing data exists.

Status & legalityWhat do these mean? →
Natty? ⓘ
Not natty
FDA ⓘ
Not approved

Not FDA approved. Pre-clinical.

Compounding ⓘ
Not classified

Not formally categorized in the FDA bulks lists.

WADA ⓘ
Not listed
Prescribed ⓘ

Not prescribed in conventional medicine.

Who it's for

  • →Researchers studying CNTF pathways
  • →Cognitive-decline research contexts
  • →Educational reference, limited human data

What to expect

  1. Week 1

    Subtle. Animal-model markers begin shifting.

  2. Week 4

    Cycle endpoint in most pre-clinical protocols.

  3. Week 8

    No human long term data.

Looking at P-21? Your next 3 steps

  1. 1Work out your exact dose

    Vial size + BAC water turns into the exact units to draw for P-21.

    Open calculator →
  2. 2See what to stack & monitor

    The companion supplements and the bloodwork worth tracking on this kind of protocol.

    Bloodwork guide →
  3. 3Save it & ask the Coach

    A free account saves your stack; membership adds the stack-aware AI Coach.

    Create free account →

How it works (mechanism)

Synthetic peptide that mimics CNTF (ciliary neurotrophic factor) action on neurogenesis pathways. Pre-clinical only, mechanism partially characterized.

Dosing protocol

Members only

Stacks well with

Members only

Side effects

01Limited human data
02Generally well tolerated in animal models

When NOT to use

  • ⚠Pregnancy / nursing
  • ⚠Anyone risk-averse to pre-clinical compounds

Common mistakes

  • • Treating it as a defined nootropic protocol
  • • Long cycles without safety data
Free, no account needed

New to P-21? Grab the starter checklist.

Drop your email and we'll send the one-page first-cycle starter checklist, plus a heads-up if P-21 changes legal status. No account needed.

No spam. No selling your email. Just the checklist and the occasional reclassification alert.

AI Coach, live sample
Members only
is 250mcg of bpc enough for a knee injury?
For a knee, 250 mcg sub-q daily is the standard working dose and a solid place to start. The trick with BPC is consistency, give it weeks, not days. Inject close to the joint, run it 4-6 weeks, and don't drop below 200 mcg, it tends to stop cracking the threshold reliably down there. If it hasn't moved at all by week 3, that's when adding TB-500 earns its place.
how much bac water for a 10mg reta vial?
3 mL is the standard play for a 10 mg reta vial. That's 3,333 mcg/mL, clean unit math across the titration: 2 mg = 60 units, 4 mg = 120 units, 6 mg = 180 units on a 100-unit insulin syringe. Run 2 mL instead if you want fewer, more concentrated shots (5,000 mcg/mL, so 2 mg = 40 units). Since most people titrate up over ~12 weeks, 3 mL keeps the numbers cleanest.
what should i track on bloodwork for tirzepatide?
Lipid panel, ALT/AST (liver enzymes), and an A1C, baseline before you start then every 3 months. If you've got metabolic-syndrome history, add fasting glucose and insulin so you can actually watch insulin sensitivity improve. You don't need a big hormone panel for a GLP-1.

Ask the Coach anything about P-21 or your own stack. This is it working.

Trained only on Pepdex content. Does the dose math, flags interactions, knows your stack. Won't push vendors, won't pretend to be a doctor.

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Frequently asked

What is P-21?+
P-21 is a synthetic peptide that mimics CNTF (ciliary neurotrophic factor). Targets neurogenesis pathways. Pre-clinical research compound, no human dosing data exists.
Is P-21 FDA approved?+
Not FDA approved. Pre-clinical.
Is P-21 legal?+
P-21 is not FDA-approved. It is sold by compounding pharmacies (with a prescription) and as "research only" by peptide vendors. Possession is generally not criminalized but distribution without authorization may be. Verify local laws.
Is P-21 banned by WADA?+
P-21 is not currently on the WADA prohibited list.
Are you still natty after taking P-21?+
No. P-21 is a performance-enhancing peptide and would disqualify a strict natty claim.
Do doctors prescribe P-21?+
Not prescribed in conventional medicine.
What's the typical dose of P-21?+
No standardized human dose. Animal-model dosing is per-kg.
What are the side effects of P-21?+
Common side effects include: Limited human data; Generally well tolerated in animal models. Less common effects and full safety details are on the entry page.
How long until P-21 starts working?+
Subtle. Animal-model markers begin shifting.
What can you stack with P-21?+
Common pairings: Standalone, too experimental. Full stacking protocol and timing on the entry page.
Where do people get P-21?+
P-21 is most commonly sold by research-only peptide vendors and by compounding pharmacies (the latter requires a prescription). Pepdex is not a vendor, see /coa for how to verify a Certificate of Analysis before buying from any source, and /guides/scam-vendor-spotting for vendor red flags.

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