Dihexa

What it is

Dihexa appears in FDA's substance record under UNII 9WYX65A5C2, with ATH-1001, PNB-0408, and N-hexanoic-Tyr-Ile-(6) aminohexanoic amide among its names. FDA's compounding page separately says Dihexa acetate. Form is part of identity, not a detail to blur.

The free-substance record and acetate wording do not prove chemical or pharmaceutical interchangeability. FDA also states that a UNII does not imply regulatory review or approval.

Why people care

Dihexa is discussed for memory, neuroplasticity, and dementia because of preclinical cognition and signaling claims. The useful question is whether those claims survived scientific scrutiny and reached people. PepCurrent found no administered-human evidence, while the best-known originating laboratory record now includes two retractions and a notice of concern.

What humans actually show

No administered-human exposure or clinical outcome study of Dihexa was identified in FDA’s current statement, the exact ClinicalTrials.gov search, or the screened PubMed search. Records involving human cells, reviews, or human-related indexing are not treatment evidence in people.

Mechanistic and nonhuman evidence

• 2024 rat toxin model: Forty male Wistar rats were randomized across vehicle, toxin, and toxin-plus-PNB-0408 groups. PNB-0408 did not protect against the reported toxin-induced weight, motor, learning, or memory deficits. This negative animal result does not establish human safety.
• 2021 APP/PS1 mouse study: The paper reported changes in water-maze performance, neuronal and synaptic markers, inflammatory markers, and PI3K/AKT signaling. These are animal and biomarker findings, not human clinical outcomes, and independent replication remains important.

FDA and U.S. status

FDA’s compounding-safety page lists Dihexa acetate among nominations withdrawn by nominators and says it has not identified human exposure data for drug products containing Dihexa acetate by any route. FDA says it lacks important information about whether the substance would cause harm.

FDA separately says it will host a Pharmacy Compounding Advisory Committee meeting before the end of February 2027 whose agenda includes Dihexa acetate for consideration for the 503A Bulks List. The exact date, time, location, and materials remain pending. This is an announced advisory process—not a vote, final list action, drug approval, or product authentication.

Exact Drugs@FDA searches for Dihexa and Dihexa acetate returned no matches on July 27, 2026. PepCurrent does not convert that result into an FDA approval, nonapproval, legality, or product-specific conclusion.

Risks and warning limits

PepCurrent located no FDA-approved Dihexa prescribing information and no exact-substance human clinical safety study. FDA says it has not identified human exposure data for Dihexa acetate and lacks important information about whether it would cause harm. Animal efficacy experiments cannot define human adverse-effect frequency, contraindications, or interactions. Missing evidence is not evidence of safety.

What remains unknown

• Human pharmacokinetics, efficacy, adverse effects, contraindications, and interactions.
• Whether free Dihexa and Dihexa acetate are equivalent in any proposed formulation.
• Whether the positive 2021 mouse findings replicate independently.
• The final disposition of the 2013 paper carrying the notice of concern.
• The exact 2027 PCAC meeting details, vote, and any later final FDA action.

Product identity and quality limits

The FDA substance record does not authenticate a marketed product. A label reading Dihexa, PNB-0408, ATH-1001, or Dihexa acetate does not establish which substance or salt is present—or its concentration, purity, sterility, stability, or handling.

What has been studied together

Because no administered-human Dihexa record was identified, PepCurrent identified no direct human coadministration or interaction evidence. Missing evidence cannot be converted into compatibility or safety, and this profile does not provide a stack or personalized combination conclusion.

What people are hearing

• “Dihexa improves memory or dementia in people.” No administered-human clinical outcome study was identified.
• “Its HGF/c-Met mechanism is established.” Two central papers supporting that story were retracted after findings involving falsified or fabricated data.
• “An online product is the material from the papers.” A name does not establish the substance form, concentration, purity, sterility, stability, or handling of an unrelated product.

Questions readers raise

Readers ask whether Dihexa is a “cognitive enhancer,” whether the retractions invalidate every remaining experiment, and whether the coming FDA meeting means approval or prohibition. Those questions help set the research agenda; they do not establish efficacy, safety, legal status, or product identity. PepCurrent has not published anecdotal theme counts or public user reviews for this profile.

What would change this answer

• A registered, well-reported administered-human study of a fully defined Dihexa product.
• Independent replication with separately characterized material.
• A final disposition for the animal paper under a notice of concern.
• The exact PCAC meeting record, vote, and any later final FDA action.
• Product-specific analytical evidence for material outside the research record.

Sources and records

• FDA compounding-safety record
• FDA planned PCAC meeting page
• FDA UNII record for Dihexa
• 2024 negative rat study — PMID 38489193
• 2021 APP/PS1 mouse study — PMID 34827486
• 2012 retraction notice — PMID 40312092
• 2014 retraction notice — PMID 40312093
• 2013 animal paper carrying a notice of concern — PMID 23055539
• Publisher notice of concern
• Reproducible PubMed search

Evidence-integrity record

• The 2012 HGF/Met-modifier paper was retracted in 2025 after a Washington State University investigation. The publisher states that Figures 3A and 4 contained falsified and/or fabricated data.
• The 2014 procognitive and synaptogenic paper was retracted in 2025. The publisher identifies Figures 1B, 2A/C, and data in a subsequent erratum submission.
• The 2013 procognitive animal paper remains linked to a journal notice of concern about possible image manipulation.

Retracted results are not affirmative evidence. A notice of concern is not a retraction, but it is a material reliability warning that must accompany any description of the affected paper.