Nootropic
P21
THERE IS ESSENTIALLY NO HUMAN DATA ON P21.
Also known as P021 · Ac-DGGL-Ag · CNTF-derived peptide mimetic · Peptide 021 derivative
NO HUMAN DATA
No human trial has ever been published for this compound. The dose, the frequency and the cycle length on this page describe what unregulated users report doing. They are not findings.
The entire evidence base is rodent. No human trial, no human pharmacokinetics, no toxicology, no approved product.
At a glance
Dose summary
No reliable human half-life has been published for P21, so none is listed rather than guessed at.
No regulator and no trial set these numbers. They describe what people actually do, recorded so you can see the range rather than guess at it — which is not the same thing as a recommendation.
Reconstitution
What to draw, at the usual vial
A 5 mg vial reconstituted with 2 mL of bacteriostatic water gives 2.50 mg/mL. A typical 500 mcg dose is 0.200 mL — pull the plunger to 20 units on a U-100 syringe.
Same dose, other vial sizes
| Vial | Water | Concentration | Draw | Units | Doses |
|---|---|---|---|---|---|
| 5 mg | 2 mL | 2.50 mg/mL | 0.200 mL | 20 units | 10 |
| 10 mg | 2 mL | 5.00 mg/mL | 0.100 mL | 10 units | 20 |
The highlighted row is the one quoted above: the smallest listed vial that holds at least four typical doses. Change any of it — a different vial, more or less water, a different dose — on the reconstitution calculator, which draws the syringe to true U-100 graduations.
Mechanism & evidence
What it is, and what is known
THERE IS ESSENTIALLY NO HUMAN DATA ON P21. It is a small adamantylated tetrapeptide derivative (Ac-DGGL-amide) of an 11-residue active region of ciliary neurotrophic factor, designed to be orally available and blood-brain-barrier permeable. The entire evidence base is preclinical: transgenic and aged rodent models of Alzheimer disease and Down syndrome, reporting increased neurogenesis and BDNF signaling and reduced tau hyperphosphorylation, from the group that developed it at the New York State Institute for Basic Research.
No human trial has been published, no human pharmacokinetic or toxicology data exists, and no approved product exists anywhere. Rodent work dosed it orally or subcutaneously; the subcutaneous and intranasal routes listed here reflect how unregulated users actually take it. The range given is deliberately narrow and conservative and is extrapolated from that practice, NOT from any dose-finding study - treat it as a description, not a recommendation.
It is frequently confused with the unrelated cell-cycle protein p21 (CDKN1A); they are not the same thing.
Tolerability
Reported side effects
- No human side-effect profile exists; nothing below is established
- Injection site redness or stinging
- Nasal irritation when used intranasally
- Headache and disturbed sleep reported anecdotally
Hard stops
Do not use this if
- Pregnancy, possible pregnancy, or breastfeeding
- Under 18
These are flags, not a screening. They do not replace a conversation with a clinician who knows your history.
Handling
Storage
Keep it cold, keep it dark, and label the vial with the date you mixed it. Discard anything cloudy or past the window above.
Combinations
Commonly stacked with
Stacking multiplies the side-effect surface and makes it impossible to tell which compound did what. Add one thing at a time.
References
Sources
Educational information only, not medical advice. Talk to a licensed clinician before starting, changing, or stopping anything.