Verified July 2026 · Cited to primary sources
Dihexa: Evidence Grade D. Animal studies only, unproven in humans.
The honest verdict
Dihexa has one of the flashiest preclinical stories in the nootropic peptide world (orders of magnitude more potent than BDNF in a dish) and almost nothing solid to stand on. Its foundational rat papers carry a retraction and an expression of concern, it has zero human data of its own, and the closest clinical drug on the same HGF/MET target failed its Alzheimer's trial in 2024. Fascinating target, unproven and integrity-flagged evidence. Not something to treat as established.
Dihexa at a glance
- Class
- Angiotensin IV-derived synthetic hexapeptide (HGF/c-Met activator)
- Mechanism
- Dihexa was engineered from angiotensin IV to be orally active and cross the blood-brain barrier. It is reported to bind hepatocyte growth factor (HGF) and enhance signaling at its receptor c-Met, which drives dendritic spine growth (spinogenesis) and new synapse formation in the hippocampus. In cell models it was described as far more potent than BDNF at promoting neurotrophic activity. This entire mechanism story rests on preclinical work, some of which now carries formal integrity flags (see below).
- Also known as
- PNB-0408, N-hexanoic-Tyr-Ile-(6) aminohexanoic amide, Angiotensin IV analog
- Research applications
- Cognitive enhancement / nootropic use
- Alzheimer's and dementia models
- Synaptic repair and neurodegeneration research
- Forms
- Oral (reported to be orally active), Subcutaneous injection (research), Transdermal / topical blends
- Legal status
- Research-only
- WADA (anti-doping)
- Not specifically named on the WADA Prohibited List.
- Evidence grade
- Grade DAnimal studies only, unproven in humans
How we grade evidence
Every grade comes from a fixed A to F rubric: human-trial strength, not hype or affiliate status. Last verified July 6, 2026.
What is Dihexa?
A lab-built angiotensin IV analog designed to supercharge brain synapse formation, and in rats it looked staggeringly potent. But it has never been proven in a human, and the drug company version built on the same target failed its big Alzheimer's trial in 2024.
Dihexa was engineered from angiotensin IV to be orally active and cross the blood-brain barrier. It is reported to bind hepatocyte growth factor (HGF) and enhance signaling at its receptor c-Met, which drives dendritic spine growth (spinogenesis) and new synapse formation in the hippocampus. In cell models it was described as far more potent than BDNF at promoting neurotrophic activity. This entire mechanism story rests on preclinical work, some of which now carries formal integrity flags (see below).
How strong is the evidence for Dihexa?
Dihexa is animal-only, and the picture is actually worse than typical preclinical uncertainty. The foundational rat studies showed dihexa reversing scopolamine-induced learning deficits and improving spatial memory in aged rats via HGF/c-Met, but the key 2014 mechanism paper has been retracted and the 2013 evaluation paper carries a formal expression of concern from the journal. On top of that, the one time this target reached humans at scale, it lost: fosgonimeton (ATH-1017), a brain-penetrant HGF/MET activator developed from the same dihexa lineage by Athira Pharma, failed its Phase 2/3 LIFT-AD Alzheimer's trial in September 2024, missing its primary and key secondary endpoints. So dihexa stays grade D on animal-only evidence, with the added honesty that its foundational data is integrity-flagged and its closest clinical relative failed in people.
Primary sources (2)
- McCoy et al. 2013, J Pharmacol Exp Ther - Evaluation of metabolically stabilized angiotensin IV analogs as procognitive/antidementia agents (rat study; dihexa reversed scopolamine learning deficits). NOTE: this paper carries a 2021 journal Expression of Concern - read it with that caveat
- ALZFORUM - Fosgonimeton (ATH-1017) therapeutics entry: documents the dihexa-derived HGF/MET drug and its FAILED Phase 2/3 LIFT-AD Alzheimer's trial (Sept 2024, missed primary and key secondary endpoints)
Is Dihexa legal? (Status July 2026)
No legal supervised US route.
What is Dihexa used for?
Dihexa is marketed for the goals below. See how it ranks against other peptides in each, by evidence, not hype.
What does Dihexa cost, and how do you access it legally?
Typical cost
$60 to $150 per 15 mg to 30 mg from research suppliers
Expensive for a research peptide, and you are paying for animal data that is partly retracted or flagged, with no human efficacy or safety behind it.
No legal supervised access route right now.
Dihexa has no compliant US route today. Vials sold "for research use only" are a gray-market fig-leaf, not a legal loophole, so we don't link them. If you pursue Dihexa, do it with a licensed clinician, and re-check its legal status first.
Is Dihexasafe? Side effects & risks
There is essentially no human safety data for dihexa itself. Its mechanism amplifies HGF/c-Met signaling, a growth pathway that is also implicated in cancer, so chronically pushing it carries a theoretical proliferation concern that has never been studied in people. Add that its foundational rat papers are integrity-flagged (one retracted, one under expression of concern) and you are looking at a compound sold on preclinical claims that are themselves in question. Amber, leaning cautious.
Medical disclaimer: This page is independent editorial information, not medical advice, and Best Peptide For That is not a medical provider. We do not provide dosing. Talk to a licensed clinician before starting, stopping, or changing any peptide or medication. Full medical disclaimer.
FAQ
Dihexa FAQ
Does dihexa improve memory in humans?
Unknown. All the memory data is from rats, and even that foundational work carries a retraction (2014 paper) and an expression of concern (2013 paper). There is no human trial of dihexa itself.
Didn't a dihexa-based drug get tested for Alzheimer's?
Yes, and it failed. Fosgonimeton (ATH-1017), built on the same HGF/MET mechanism, missed its primary and key secondary endpoints in the Phase 2/3 LIFT-AD trial in September 2024.
Is dihexa safe?
There is no human safety data. Because it amplifies a growth pathway (HGF/c-Met) that is also linked to cancer biology, there is a theoretical proliferation concern that has never been tested in people.
Is dihexa FDA approved or legal?
No. It is not approved for any use and is sold only as a research chemical, not a compoundable medicine.
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