Dihexa: the basics
What is it?
A small lab-made molecule built from a piece of angiotensin IV, a peptide found in the brain. It was designed in a university lab as a possible dementia drug.
Research paper 1 ↗Research paper 2 ↗Research paper 3 ↗Research paper 4 ↗What do people claim it helps with?
Sharper memory, faster learning and brain repair. None of these has been tested in published human studies.
What has research actually shown?
Rats and mice given dihexa did better on some memory tests, but a rat study of a Huntington's-like illness found no benefit. A major paper explaining how it works was retracted in 2025.
Research paper 1 ↗Research paper 2 ↗Research paper 3 ↗Research paper 4 ↗Has this been demonstrated in people?
Only laboratory cell and animal studies. FDA says it has found no human exposure data at all.
Research paper 1 ↗Research paper 2 ↗Research paper 3 ↗Research paper 4 ↗What side effects, risks and unknowns should I understand?
Unknown in people. It was designed to boost growth-factor signaling, and long-term effects of that in humans have not been studied.
FDA safety information ↗Is it an approved medicine?
No FDA-approved medicine contains this compound. Availability online or through a clinic does not mean it has been approved.
FDA safety information ↗Approval here means U.S. FDA approval and applies to a particular product, formulation and use. This is a starting overview, not a complete side-effect list. Sources checked 10 October 2026; independent scientific review pending.
How is it used or studied?
Animal studies gave it by mouth. There is no approved human formulation, and an online product may not match what was studied.
Different routes and formulations can have different effects. A study of one product does not validate every product with the same peptide name.
A common misunderstanding
Fosgonimeton is a related but different drug that was tested in people with Alzheimer's and missed its main goal. Its results are not dihexa results.
What should I ask a clinician?
- What diagnosis or goal are we trying to address, and what established options are available?
- Was the expected benefit shown in people like me, using this exact product?
- How could my medicines, health conditions or pregnancy plans affect the risks?
- What monitoring is needed, and what would tell us the treatment is helping or should be stopped?
What do the research words mean?
- Peptide
- A short chain of amino acids, the building blocks of proteins.
- Preclinical
- Research in cells, tissues or animals before dependable treatment evidence in people.
- Controlled trial
- A study comparing a treatment with another treatment or a placebo to help separate its effects from other explanations.
- Biomarker
- A measurement, such as a hormone level. A change does not necessarily mean someone feels better or lives longer.
Dihexa Evidence & Clinical Profile
Human Study Limits
Dihexa has been investigated in clinical contexts. Patient outcomes must be evaluated against study size, design, and control cohorts.
Laboratory & In Vivo Assays
Cellular and animal disease models examine receptor binding affinities and signaling cascades, which require human confirmation.
What is Dihexa?
N-hexanoic-Tyr-Ile-(6)-aminohexanoic amide is Dihexa is a small, modified fragment of the brain peptide angiotensin IV, developed in a university lab as a possible dementia treatment. All published evidence comes from animals and cells, and a key paper on how it works was retracted in 2025. FDA says it has found no human exposure data. Aliases include: PNB-0408, ATH-1001, Hexanoyl-Tyr-Ile-Ahx-NH2, Dihexa acetate.
- Sequence (one-letter)
- Hexanoyl-Tyr-Ile-(6)-aminohexanoic amide
- Molecular formula
- C27H44N4O5
- Molecular weight
- 504.7 g/mol
- CAS Number
- 1401708-83-5
- UNII Code
- 9WYX65A5C2
- PubChem CID
- 129010512
Identifiers checked against PubChem and FDA's Global Substance Registration System on 13 October 2026. FDA substance record ↗ · PubChem record ↗ See all names and codes in the peptide name index.
Clinical Trials & Human Cohorts
Human research can examine tolerability, symptoms or patient outcomes. The design and comparator determine what each result can establish.
How the compound may work
Mechanisms describe how Dihexa may affect biological processes. Laboratory findings and patient outcomes answer different questions.
Hepatocyte growth factor (HGF)/c-Met hypothesis
A 2014 paper proposed that dihexa works by binding HGF and boosting c-Met signaling to build new synapses. That paper was retracted in 2025, so this mechanism should be treated as unconfirmed. [2]
Synapse growth in rodent models
The developers reported that dihexa reversed memory deficits in scopolamine-treated and aged rats and increased synapse formation. This paper carries a 2021 expression of concern from the journal. [1]
Areas Being Studied
These research topics reflect active areas of scientific exploration, distinct from unverified commercial marketing claims.
Alzheimer's-type memory deficits
An independent group reported improved water-maze performance and reduced brain inflammation markers in mice. Mouse results do not show benefit in people. [4]
Huntington's-like model (negative)
In this rat model, dihexa did not protect against weight loss, motor problems or memory deficits. [5]
Related compound in humans
PubChem's structure for fosgonimeton is dihexa with a phosphate added. In a 287-person primary analysis it did not significantly improve cognition or daily function versus placebo. These results do not apply directly to dihexa. [8]
Compare the study designs.
| Study | Design / sample | Outcome type | Key limitation |
|---|
Regulatory Status & Clinical Safety
Regulatory Classification
United States, checked 11 October 2026: no FDA-approved medicine contains dihexa. FDA lists dihexa acetate among bulk drug substances that may present significant safety risks in compounding, stating it has not identified any human exposure data for any route and lacks information on whether it would harm people. Fosgonimeton, a related phosphate prodrug developed by a company, is a separate investigational compound; its Phase 2/3 Alzheimer's trial missed its primary endpoint.
Safety Realities & Impurities
Safety depends on the molecule, formulation, route and evidence. A laboratory purity measurement alone cannot establish safety for human use.
Clinical Trials Registry Records
Official registry records from ClinicalTrials.gov. Study registration does not imply government endorsement or guaranteed efficacy.
WADA & Anti-Doping Regulations
WADA Anti-Doping Status
Dihexa is not prohibited under current World Anti-Doping Agency (WADA) regulations. However, athletes must ensure unregulated preparations or unverified vendor products do not violate Section S0 (Non-approved substances). Last verified: October 2026.
Research Timeline
-
2013
Dihexa described
University researchers report an orally active, brain-penetrant angiotensin IV analogue in rats. [1]
-
2018
Animal evidence reviewed
A systematic review of non-human studies includes dihexa among angiotensin IV analogues that improved memory tasks. [6]
-
2021
Expression of concern
The journal issues an expression of concern about the 2013 dihexa paper. [1]
-
2025
Mechanism paper retracted
The 2014 HGF/c-Met mechanism paper is retracted. [3]
-
2026
FDA: no human data
FDA lists dihexa acetate as a compounding safety concern with no identified human exposure data. [7]
What Researchers Still Don't Know
Long-term safety profiles
Multi-year observational data in broader heterogeneous cohorts remains uncharacterized.
Optimal dose-response thresholds
Comparative trials optimizing minimal effective exposure versus adverse event rates.
Formulation bioavailability
Differences between oral, subcutaneous, and modified peptide delivery vehicles.
References
Primary sources verified against PubMed / NLM and regulatory databases.
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Animal research (expression of concern 2021)
PubMed links a 2021 expression of concern (J Pharmacol Exp Ther 378(3):313).
-
Retracted animal and cell research
Retracted in 2025; see retraction notice.
- Retraction notice
- Animal research (mouse)
- Animal research (rat, negative)
- Systematic review of animal studies
- FDA compounding safety list
-
Phase 2/3 trial of a related compound (company-sponsored)
Fosgonimeton in mild-to-moderate Alzheimer's disease ↗ (external website)
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Registry Record (fosgonimeton, not dihexa)
ATH-1017 for Treatment of Mild to Moderate Alzheimer's Disease ↗ (external website)
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Developer review
Authors were affiliated with Washington State University and M3 Biotechnology, Inc.