Head to head
Dihexa against P21
Two experimental neurotrophic peptides sold on animal synaptogenesis and neurogenesis results. Neither has a human study of any design, and the two are frequently cross-shopped on vendor sites as if they were graded versions of the same thing.
Column A
DihexaDihexa (angiotensin IV analogue)
An experimental angiotensin-derived peptide reported to be an extremely potent promoter of new synapse formation in animal models of cognition.
Column B
P21P21 (P021, CNTF-derived peptide)
A small peptide derived from a neurotrophic factor studied for promoting new neuron growth and protecting against Alzheimer-like changes in animals.
Side by side, on the facts we can check
| Attribute | Dihexa | P21 |
|---|---|---|
| Category | Nootropic & CNS | Nootropic & CNS |
| FDA status | Not FDA-approved; experimental | Not FDA-approved; experimental |
| Half-life | Short | Short |
| Molecular weight | ~564 Da | ~650 Da |
| Mechanism | Potentiates hepatocyte growth factor and its c-Met receptor to drive synaptogenesis, the formation of new synaptic connections. | Mimics ciliary neurotrophic factor signaling to promote new neuron formation and synaptic plasticity in the hippocampus. |
| Human studies cited | 0 | 0 |
| Legal status, US | Not approved; research use only | Not approved; research use only |
Frequently asked questions
What is the difference between Dihexa and P21?
Dihexa: An experimental angiotensin-derived peptide reported to be an extremely potent promoter of new synapse formation in animal models of cognition. P21: A small peptide derived from a neurotrophic factor studied for promoting new neuron growth and protecting against Alzheimer-like changes in animals.
Which has stronger research evidence, Dihexa or P21?
This database does not grade compounds. It counts what was run in people: 0 of the 2 studies cited on the Dihexa profile were human work, against 0 of 3 for P21. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are Dihexa and P21 FDA-approved?
Dihexa: Not FDA-approved; experimental. P21: Not FDA-approved; experimental.
Reviewed Sep 2026. This page sets two published records side by side. It is educational, it is not medical advice, and it contains no dosing protocols or recommendations for personal use.