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Dihexa Peptide: Angiotensin IV Analogue, HGF/c-Met Signaling, and the Evidence Gap
A small, modified angiotensin IV–derived peptide studied in animal models for synaptic connectivity through the HGF/c-Met pathway. There are no published human trials and no established human dose.
Dihexa is a small synthetic peptide derived from angiotensin IV, studied in laboratory and animal models for its effects on synaptic connectivity and memory. It is discussed in nootropic and neurological circles as a "cognitive" peptide, often alongside Semax and Selank, but its evidence base is fundamentally different from theirs: there are no published human clinical trials of dihexa. Everything known about its effects comes from cell and animal work. This page covers what the dihexa peptide is, the mechanism it has been studied for, what the research does and does not show, and where it stands with the FDA.
This page is educational and written for licensed prescribers. It is not medical advice.
What Is Dihexa?
An Angiotensin IV Derivative
Angiotensin IV is a fragment of the renin–angiotensin system, the hormonal cascade best known for regulating blood pressure. Beyond its vascular roles, angiotensin IV attracted research interest in the 1990s and 2000s after animal studies suggested it could influence learning and memory. Native angiotensin IV is a poor drug candidate, however: it is broken down quickly and does not cross the blood–brain barrier well.
Dihexa was developed by academic researchers as a modified, stabilized analogue intended to overcome those limitations. Its structure is a heavily modified short peptide with a hexanoic acid cap on one end and an aminohexanoic amide on the other — the modifications that give the compound its name and that were designed to improve metabolic stability and brain penetration. In the published preclinical work, it was reported to be active after oral administration in rodents, which is unusual for a peptide.
Where the Name "Dihexa" Comes From
The name refers to the two six-carbon (hexa-) groups added to the peptide core. It is sometimes written as N-hexanoic-Tyr-Ile-(6) aminohexanoic amide in the research literature, and the acetate salt ("dihexa acetate") is the form that appears in FDA nomination records.
How Dihexa Is Thought to Work
The HGF/c-Met Pathway
The mechanism most associated with dihexa is its interaction with hepatocyte growth factor (HGF) and its receptor, c-Met. HGF is a growth factor with roles well beyond the liver: in the nervous system, HGF/c-Met signaling has been linked to neuronal survival, dendritic growth, and the formation of new synaptic connections.
Preclinical research reported that dihexa binds HGF and promotes HGF dimerization, a step that facilitates activation of the c-Met receptor. In that model, dihexa does not act as a classic receptor agonist; it amplifies signaling by an endogenous growth factor.
Synaptogenesis in Animal Models
The effect most often cited for dihexa is synaptogenesis — the formation of new connections between neurons. In cell culture and in rodent models of cognitive impairment, dihexa was reported to increase dendritic spine density and to improve performance on memory tasks. Those findings are the basis for the "cognitive enhancer" reputation dihexa has online.
Why That Mechanism Also Raises Questions
HGF/c-Met is a double-edged pathway. The same signaling that supports cell growth and survival is a well-described driver in several cancers, where c-Met overactivity promotes tumor growth, invasion, and metastasis. Many oncology drug programs are built around inhibiting c-Met. A compound designed to amplify HGF/c-Met signaling therefore carries a theoretical oncogenic concern that has never been tested in long-term human studies. This is not proof of harm — it is an unanswered question, and it is the central safety issue any clinician should understand before discussing dihexa.
What the Research Shows — and Doesn't
| Question | What the evidence supports |
|---|---|
| Does dihexa affect synapse formation? | In cell culture and rodent models, reported yes |
| Does it improve memory in animals? | Reported improvements in rodent models of cognitive impairment |
| Has it been tested in humans? | No published human clinical trials |
| Is there human pharmacokinetic data? | None published |
| Is there a human dose? | No established human dose |
| Is long-term safety known? | No — the c-Met oncogenic question is untested |
The Evidence Is Preclinical Only
The dihexa literature is small and comes largely from the academic group that developed it. The studies are mechanistic and animal-based. There are no randomized trials, no dose-finding studies, no human pharmacokinetic data, and no systematic human safety data. Reports circulating online about human effects are anecdotal and cannot be verified.
Why Animal Results Don't Translate Directly
The closest human evidence in this drug class is a cautionary one: fosgonimeton (ATH-1017), a different small molecule designed as a positive modulator of the same HGF/c-Met system, did not meet its primary endpoint in the Phase 2/3 LIFT-AD trial in Alzheimer's disease (2024). That result does not test dihexa itself, but it is the only controlled human readout for the mechanism.
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Rodent memory models measure specific behaviors under controlled conditions of induced impairment. Positive results there are a reason for further study, not evidence of cognitive benefit in people — and a large share of compounds that improve memory in rodents never show benefit in humans. For dihexa, the translation step has simply not been attempted in published research.
Dihexa Benefits: What Can Honestly Be Said
People searching for dihexa benefits usually encounter claims of improved memory, focus, and recovery from cognitive decline. The accurate summary is narrower:
- Studied for: synaptic connectivity and memory in animal models of impairment.
- Proposed mechanism: amplification of HGF/c-Met signaling.
- Shown in humans: nothing — no published human trials exist.
Any benefit in people is currently hypothetical. That distinguishes dihexa from Semax and Selank, which, whatever the limits of their evidence, have been studied in humans and are registered medicines in Russia. For how the cognitive peptides compare, see our nootropic peptides guide and Semax and Selank compared.
Dosage: No Established Human Dose
There is no established human dose of dihexa. With no human pharmacokinetic studies and no dose-finding trials, there is no evidence base from which a dose could be derived. Doses that circulate online are extrapolations from animal studies or anecdote, and they should not be treated as clinical guidance. This page deliberately gives no dosing information.
Safety Considerations
- Theoretical oncogenic risk. Because dihexa is designed to enhance HGF/c-Met signaling — a pathway implicated in tumor growth — the possibility of promoting existing or occult malignancy is the principal unanswered concern. It has not been studied.
- No human safety data. Adverse-effect profiles, drug interactions, and effects in specific populations are unknown.
- Product quality. Dihexa sold online as a "research chemical" is not made or tested to pharmaceutical standards, and its identity and purity cannot be assumed.
- Pregnancy and breastfeeding. No data; growth-factor modulation makes use inappropriate.
Regulatory Status
Dihexa is not an FDA-approved drug. Its regulatory path in compounding has moved in 2026:
- The site's April 2026 Category 2 update lists dihexa among the peptides removed from Category 2.
- Our FDA peptide status tracker lists dihexa acetate as scheduled for a Pharmacy Compounding Advisory Committee (PCAC) review before the end of February 2027. Its nomination had previously been withdrawn, with the lack of human exposure data cited as a concern, and it is now being reconsidered.
Being scheduled for review is not the same as being eligible. Until the FDA acts on the PCAC's advice, dihexa has no established 503A compounding pathway, and the absence of human data that led to its earlier withdrawal has not changed. Check the tracker for current status.
Frequently Asked Questions
What is dihexa?
Dihexa is a small synthetic peptide derived from angiotensin IV, modified to resist breakdown and to reach the brain. In animal research it has been studied for promoting synapse formation through the HGF/c-Met pathway.
What are dihexa's benefits?
In rodent models of cognitive impairment, dihexa was reported to improve memory-task performance and increase synaptic connections. There are no published human trials, so benefits in people have not been demonstrated.
Is there a safe dihexa dose?
No established human dose exists. There are no human pharmacokinetic or dose-finding studies, so no dose can be called safe or effective. This page gives no dosing guidance.
Why is c-Met signaling a safety concern?
The HGF/c-Met pathway supports cell growth and survival and is a known driver in several cancers. Because dihexa is designed to amplify that signaling, a theoretical risk of promoting tumor growth exists. It has never been evaluated in long-term human studies.
Is dihexa FDA-approved or legal to compound?
Dihexa is not FDA-approved. The FDA tracker lists it as scheduled for PCAC review before the end of February 2027 after an earlier withdrawal; until the FDA acts, it has no established 503A compounding pathway. Check the FDA peptide status tracker for current status.
How does dihexa compare with Semax and Selank?
Semax and Selank have been studied in humans and are registered medicines in Russia; dihexa has only animal data. See Semax and Selank compared and the nootropic peptides guide.
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