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№ 053

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 syringe units

    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 starter checklist beginners actually need first. No account needed.

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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?+
Dosing depends on your goal, experience, and tolerance. The full P-21 protocol (dose, frequency, and how to titrate) is in the members section on the entry page.
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?+
P-21 is commonly combined with complementary compounds. The full stacking protocol (what to pair, dosing, and timing) is in the members section on the entry page.
Where do people get P-21?+
Pepdex does not sell, ship, or recommend suppliers. P-21 is not FDA-approved; prescription versions require licensed clinical care, and "research only" markets carry real legal and quality risks. /coa explains how to verify a Certificate of Analysis and /guides/scam-vendor-spotting covers the red flags.

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