Gathering the record
Relay is organizing the evidence and source boundaries.
Experimental angiotensin-IV-derived peptidomimetic
Dihexa is an experimental angiotensin-IV-derived peptidomimetic studied mainly in rodent cognition and neuronal-culture models. No human efficacy, pharmacokinetic, or safety study was identified.
60-Second Overview
Start with what it is, why it matters, what research has shown, and what remains unknown. The science follows after the orientation.
Start here. These four answers explain why the compound matters before the page introduces the deeper science.
Dihexa is an experimental small molecule derived from angiotensin-IV research. It is designed to influence a growth-signaling pathway involved in connections between nerve cells.
Rodent learning studies and neuron cultures produced signals related to memory and new synaptic structures. Researchers also study the pathway because changing growth signals could create important safety questions.
In rats and mice, Dihexa improved selected learning measures in some models and altered dendritic-spine or inflammatory markers. One Huntington-like rodent model was negative. No human exposure, pharmacokinetic, safety, or efficacy study was identified.
Human absorption, target engagement, cognition effects, repeated-use toxicity, product identity, and every route-specific safety question remain unknown. Growth-pathway activity, including possible cancer-related implications, cannot be resolved from short animal and cell experiments.
The research depth, routes, studies, and primary sources below explain how Relay knows—and where the evidence stops.
Research context
Published research has investigated this compound using the following study designs.
These records explain what researchers did. They are not instructions, recommendations, or a transferable protocol.
Published research investigated Dihexa in rodent learning models and cultured rat neurons to examine behavior, synaptic structure, and pathway dependence.
Reported study administration—not a recommendation.
Research at a glance
Evidence depth, confidence, and route context explain how Relay knows—not what anyone should do.
A small set of cell and rodent studies reports synaptic and behavioral effects; no human exposure was found.
Research depth describes how large and mature the overall record is. It does not tell you whether the results were positive.
Disease-model results are mixed and there is no human pharmacokinetic, efficacy, or safety program.
Confidence describes how reliable and consistent the conclusions are. It can be high for one outcome and low for another.
The strongest evidence type shows what the best-supported conclusions are actually based on.
Human findings are more directly relevant than animal or laboratory results, but they still apply only to the populations and outcomes studied.
Route-specific record
These are exposures used in cited research for a specific route and population—not an instruction for an individual.
Half-life describes how long it takes the measured amount in the body to fall by half. It is not a dosing recommendation.
Evidence can change by administration method. Findings from one route should not automatically be applied to another.
Evidence boundary: No verified human exposure, pharmacokinetic, efficacy, or safety study was located. Rodent behavior and cell morphology cannot establish human cognition benefit or resolve growth-pathway and cancer-related safety questions. Amounts shown describe cited research exposure—not a dosage recommendation.
Detailed evidence
Start with the strongest supported conclusion and its main uncertainty. Claim-level records below show how the evidence changes by question, population, route, formulation, and study design.
None identified. The evidence base consists of laboratory and animal studies plus official safety and search audits.
This is the strongest supported conclusion in the current human evidence—not a summary of every claim made about the compound.
Human exposure, target engagement, pharmacokinetics, cancer-related c-Met pathway implications, repeated-use toxicity, cognition outcomes, product identity, and every route-specific safety question.
Keeping the main uncertainty visible prevents an early or promising finding from looking more settled than it is.
Questions people bring to the evidence
Research questions—not promises of benefit.
It is chemically distinct from native angiotensin IV and from unrelated HGF-pathway drug candidates.
HGF-pathway blockade reduced the observed rodent and cell effects.
These are proof-of-concept signals, not human nootropic evidence.
The evidence is not uniformly positive across disease models.
Claims for human memory, focus, neuroprotection, dementia treatment, or oral bioavailability are unproven.
FDA lacks essential information needed to determine whether such products could harm humans.
No approved Dihexa product or human therapeutic window exists.
Mechanisms
Dihexa (PNB-0408) is a metabolically stabilized AngIV-derived peptidomimetic designed for oral activity and brain exposure in rodents. Preclinical work reports facilitation of HGF/c-Met signaling, hippocampal spinogenesis, synaptogenesis, and improved performance in selected rodent cognitive models. An APP/PS1 mouse study linked effects to PI3K/AKT signaling, while a 2024 3-nitropropionic-acid Huntington-like model did not find efficacy on its target outcomes. No human clinical trial, dose-ranging study, pharmacokinetic study, or safety program was identified. FDA specifically reports no identified human exposure data for compounded dihexa acetate, making cognition, neuroprotection, route, dose, and safety claims unestablished.
A plausible mechanism can explain why a study was attempted. It does not prove that the compound improves a human outcome.
Studies
Study arms are reported for transparency. They describe what researchers did in a defined record and do not transfer across identities, routes, formulations, or populations.
A later trial phase can ask a more mature question, but it does not guarantee a positive result, regulatory approval, or relevance outside the studied population.
Controlled 3-nitropropionic-acid rodent model
Rodents with chemically induced Huntington-like pathology
PNB-0408 did not show efficacy for preventing the targeted Huntington-like symptoms in this model.
Study administration: PNB-0408 or controls
Limitations: A negative result in one model does not settle every possible indication, but it counters universal neuroprotection claims.
Controlled APP/PS1 mouse experiment
APP/PS1 transgenic mice
The study reported improved cognition-related outcomes and altered inflammatory and PI3K/AKT measures.
Study administration: Intragastric Dihexa at two experimental amounts or controls
Limitations: APP/PS1 mice do not reproduce the full human disease, and treatment amounts and outcomes cannot be translated into human use.
Rodent cognition and neuronal-culture experiments with HGF/c-Met blockade
Scopolamine-impaired rats and cultured hippocampal neurons
Blocking HGF/c-Met signaling attenuated Dihexa-associated procognitive and synaptogenic effects.
Study administration: Dihexa with or without an HGF antagonist
Limitations: Mechanistic dependence in rodent systems does not prove safe or beneficial human MET modulation.
Rodent behavioral studies plus hippocampal neuron culture
Scopolamine-impaired and aged rats; cultured rat hippocampal neurons
Dihexa improved selected rodent spatial-learning outcomes and increased dendritic-spine measures in neuronal culture.
Study administration: Dihexa versus controls in preclinical protocols
Limitations: Rodent cognition and cell morphology do not establish human cognitive efficacy or safety; several pharmacokinetic claims rely on limited preclinical characterization.
ClinicalTrials.gov and FDA evidence review
Population not stated.
No registered human Dihexa trial was identified, and FDA reports no identified human exposure data for compounded dihexa acetate.
Study administration: Not stated in the current record.
Limitations: Searches can change over time, but the absence of human exposure prevents clinical claims.
Safety snapshot
No human Dihexa efficacy, pharmacokinetic, dose-ranging, or safety trial was identified.
No direct evidenceA future exact-compound trial could change the evidence state.
Open sourceThe current record does not support a reliable common-versus-uncommon frequency split.
Evidence boundaryUnder-detected or under-reported events must not be described as rare.
No source-qualified compound-specific warning or contraindication is encoded in the current record.
Evidence boundaryNot approved; no identified human exposure data Human exposure, target engagement, pharmacokinetics, cancer-related c-Met pathway implications, repeated-use toxicity, cognition outcomes, product identity, and every route-specific safety question.
The current record does not identify a reliable compound-specific pattern of events that caused study discontinuation.
Evidence boundaryThis is an evidence gap, not proof that discontinuations did not occur.
No compound-specific patient-facing urgent-action threshold is established in the current Relay record.
Evidence boundaryRelay does not infer emergency guidance from study discontinuations, mechanism, or incomplete adverse-event reporting.
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