How many units of P21 should I draw?

It depends on your vial size, BAC water, and dose. For a 5mg vial with 2mL BAC water, a beginner dose of 100mcg is typically 4 units on a U-100 syringe. Use the calculator above for your exact numbers.

How much BAC water should I add to P21?

The standard amount is 2mL of bacteriostatic water for a 5mg vial. More water gives a more dilute solution — easier to measure small doses. Less water means fewer injections per vial. Adjust the BAC water slider in the calculator to see how it changes your syringe units.

How long does a P21 vial last?

At a beginner dose of 100mcg daily, a 5mg vial lasts about 50 doses. The calculator shows exact doses per vial for your selected tier.

What syringe should I use for P21?

Most people use a U-100 insulin syringe (1mL / 100 units). For very small doses, a U-50 or U-30 syringe gives better precision. The calculator adjusts units automatically for whichever syringe you pick.

P21 Dosage Calculator

CognitiveInjection/NasalResearch~3+ hours half-life

P21 (also designated P021) is a synthetic tetrapeptide derived from the biologically active region of human ciliary neurotrophic factor (CNTF), specifically amino acid residues 148-151.

Promoted hippocampal neurogenesis and dendritic maturation in multiple mouse modelsReduced tau hyperphosphorylation by 50-60% in triple transgenic Alzheimer's miceCrosses the blood-brain barrier after peripheral administrationEnhanced spatial learning and reference memory in normal adult mice4 weeks on / 4 weeks off

Vial Size

BAC Water (mL)

Dosing Level

100mcg · Daily

Custom Dose (mcg) — optional

Syringe Type

4.0 units

100 units (1mL)

Concentration

2,500

mcg/mL

Draw Volume

0.040

Syringe Units

4.0

units

Doses / Vial

doses

Summary: Add 2mL BAC water to your 5mg vial. Draw to 4.0 units on a U-100 syringe for a 100mcg dose. This vial will last 50 doses.

Cycle Planner

Cycle Length (weeks)

Price Per Vial ($) — optional

Intranasal or Subcutaneous. Typical beginner frequency: daily.

P21 Pharmacokinetics

P21 Dosing Protocol

Level	Dose / Injection	Frequency
Beginner	100mcg	Daily
Moderate	300mcg	Daily
Aggressive	500mcg	Daily

Note: CNTF-derived tetrapeptide (residues 148-151) with adamantylated glycine C-terminal cap. Crosses the blood-brain barrier. Intranasal or subcutaneous. Preclinical only — no human trials. Cycle 4 weeks on, 2-4 weeks off.

About P21

P21 (also designated P021) is a synthetic tetrapeptide derived from the biologically active region of human ciliary neurotrophic factor (CNTF), specifically amino acid residues 148-151. An adamantylated glycine group was added to the C-terminal to improve blood-brain barrier permeability and protect against enzymatic degradation by exopeptidases. Unlike full-length CNTF, which is too large to cross the blood-brain barrier and carries systemic side effects including weight loss and antibody formation, P21 was engineered to retain the neurotrophic benefits while eliminating these drawbacks. Its primary mechanism involves competitive inhibition of leukemia inhibitory factor (LIF) signaling, which normally acts as a brake on hippocampal neurogenesis. By suppressing LIF, P21 allows endogenous neurogenic processes to proceed more effectively, leading to increased BDNF expression, TrkB receptor activation, and downstream CREB phosphorylation. Preclinical evidence comes primarily from the laboratory of Dr. Khalid Iqbal at the New York State Institute for Basic Research in Developmental Disabilities. In 3xTg-AD mice (a triple transgenic Alzheimer's model), P21 reduced tau hyperphosphorylation by 50-60%, increased hippocampal neurogenesis approximately threefold, and prevented synaptic loss. In normal adult C57BL/6 mice, it enhanced spatial reference memory and promoted maturation of newly born neurons in the dentate gyrus. All existing data comes from animal studies. No Phase I, II, or III human clinical trials have been conducted, and the long-term safety profile in humans remains entirely unknown. This compound should be considered strictly experimental.

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