The UK's Leading Dihexa Resource
Evidence-based information on Dihexa (PNB-0408). Honest science. No hype.
What is Dihexa?
Dihexa (PNB-0408) is a synthetic oligopeptide derived from angiotensin IV, developed at Washington State University in the laboratory of Dr Joseph Harding. It activates the HGF/c-Met pathway in the brain, driving the formation of new synaptic connections — a process called synaptogenesis.
In preclinical work, Dihexa promoted dendritic spine formation at concentrations reported to be far more potent than BDNF on a molar basis in specific assays [McCoy et al., 2013]. All current evidence is animal or in vitro — no completed human trials exist for Dihexa itself.
Featured Research Articles
In-depth, UK-focused condition reviews covering the latest 2025-2026 science. Updated regularly.
Dihexa for Autism Spectrum Disorder (ASD)
The Campbell rs1858830 MET promoter C-allele autism finding (the strongest mechanistic anchor to Dihexa pharmacology), the January 2026 mGluR5 PET 16-23% lower availability, the December 2025 DAYBUE STIX (trofinetide) Rett approval, the March 2026 FDA leucovorin decision (CFD only, not autism), the 270,701 NHS open referrals breaching NICE NG142, and the ~700,000 UK autistic population.
Read review → 27 May 2026Dihexa for Migraine & Chronic Migraine
The May 2024 NICE TA973 atogepant (Aquipta, AbbVie) approval, the rimegepant / erenumab / galcanezumab / fremanezumab / eptinezumab CGRP pathway, 2025 chronic-migraine hippocampal atrophy & accelerated brain ageing research, the Tanure BDNF-elevated-in-attack paradox, NICE NG150, and the ~10 million UK migraine population.
Read review → 26 May 2026Dihexa for ME/CFS (Myalgic Encephalomyelitis)
DecodeME GWAS preprint Aug 2025 (8 loci, female-only signal), UK ME/CFS Delivery Plan ‘My Full Reality’ July 2025, NIH Walitt 2024 deep-phenotyping, UBC Nacul LDN trial, NICE NG206, and the ~250,000 UK ME/CFS population.
Read review → 26 May 2026 · NewDihexa for Sleep Apnea Brain Fog
OSA & hypoxemia, REM CA1 hippocampal loss (UC Irvine May 2025), Zepbound (tirzepatide) FDA approval Dec 2024 (SURMOUNT-OSA), NICE NG202, and the ~13 million UK adults estimated to have OSA.
Read review → 23 May 2026 · NewDihexa for OCD
HGF/GABA biology, Russo 2013, troriluzole BHV-4157 failure, psilocybin COMP360, and the 750,000 UK OCD population.
Read review → 22 May 2026 · NewDihexa for Tinnitus & Hyperacusis
Lenire neuromodulation, Susan Shore Auricle, cochlear synaptopathy, and the 7.6 million UK tinnitus population.
Read review → 2026 ReviewDihexa for Vascular Dementia
17% of UK dementia, UCLA April 2026 breakthrough, MarkVCID biomarkers, and the HGF/c-Met angiogenesis case.
Read review → 2026 ReviewDihexa for Frontotemporal Dementia
The October 2025 Alector latozinemab Phase 3 failure, progranulin biology, and the 31,000 UK FTD population.
Read review → 2026 ReviewDihexa for Schizophrenia
KarXT/Cobenfy first non-D2 mechanism in 30 years, iclepertin CONNEX failure, and C4 synaptic pruning.
Read review → 2026 ReviewDihexa for Huntington’s Disease
AMT-130 gene therapy 75% slowing, WVE-003 allele-selective lowering, and the corticostriatal BDNF/TrkB axis.
Read review → 2026 ReviewDihexa for Lewy Body Dementia
CervoMed neflamapimod Phase 2b/3, alpha-synuclein seed amplification, and 100,000 UK DLB patients.
Read review → 2026 ReviewDihexa for Parkinson’s Disease
The NIHR PD Translational Research Collaboration, fosgonimeton SHAPE PDD signal, and 153,000 UK PD patients.
Read review →Explore Our Research
Dive deep into every aspect of Dihexa — from molecular mechanisms to UK legal considerations.
Mechanism of Action
How Dihexa activates the HGF/c-Met pathway to promote synaptogenesis, dendritic spine formation, and long-term potentiation.
Read more →Potential Benefits
Memory, learning, neuroplasticity, neuroprotection — what the preclinical evidence actually says, with honest caveats.
Read more →Dosage Guide
Animal research doses, anecdotal community protocols, routes of administration, and cycling strategies.
Read more →Side Effects & Risks
The c-Met/oncogenic concern, retracted research, WADA status, drug interactions, and who should avoid Dihexa.
Read more →Research & Evidence
Complete analysis of key studies including the 2014 retraction, LIFT-AD failure, and independent supporting data.
Read more →UK Legal Status
Dihexa's position under UK law: not controlled, not licensed as a medicine, sold as a research chemical.
Read more →Dihexa Research Timeline
Key milestones in the scientific journey of Dihexa and related compounds.
Original Discovery Published
McCoy et al. publish landmark study demonstrating Dihexa's synaptogenic properties via HGF/c-Met activation at Washington State University [McCoy et al., 2013].
Benoist et al. Study (Later Retracted)
Follow-up study published on Dihexa's cognitive effects. Later retracted due to data fabrication concerns involving Kawas and Harding [Benoist et al., 2014 — RETRACTED].
Wright & Harding Review
Comprehensive review of angiotensin IV analogs and their cognitive effects published [Wright & Harding, 2015].
Fosgonimeton Phase 1 Trials
M3 Biotechnology (later Athira Pharma) completes Phase 1 safety trials of fosgonimeton, a prodrug of Dihexa. Deemed safe and well-tolerated.
Athira Pharma Scandal & Independent Support
CEO Leen Kawas resigns amid data falsification allegations. Separately, Sun et al. publish independent supportive data in APP/PS1 mice [Sun et al., 2021].
ACT-AD Phase 2 Trial
Fosgonimeton's Phase 2 ACT-AD trial in Alzheimer's patients fails its primary endpoint.
LIFT-AD Phase 2/3 Failure
The larger LIFT-AD trial fails both primary and key secondary endpoints, raising questions about the clinical viability of fosgonimeton.
Athira Settles False Claims Act
Athira Pharma settles for $4 million with the US Department of Justice related to NIH grants using compromised research data.
Frequently Asked Questions
Quick answers to the most common questions about Dihexa. See our full FAQ page for 25+ questions.
Dihexa (PNB-0408) is a synthetic peptide derived from angiotensin IV, developed at Washington State University. It activates the HGF/c-Met receptor pathway in the brain, promoting the formation of new synaptic connections (synaptogenesis). In preclinical studies, it has shown remarkable effects on memory and learning in animal models. All current evidence is from animal and cell studies — there are no completed human trials for Dihexa itself. Learn more about Dihexa.
Dihexa is not a controlled substance under the Misuse of Drugs Act 1971 and is not listed under the Psychoactive Substances Act 2016. It is not licensed as a medicine by the MHRA. It occupies a grey area: legal to purchase for research purposes, but it cannot be sold as a medicine or for human consumption. Read our full UK legal analysis.
The honest answer is that we don't know for certain. Dihexa activates the c-Met receptor pathway, which is also involved in certain cancers — creating a theoretical oncogenic concern. There is no long-term human safety data. A key supporting study was retracted due to data fabrication, and the related prodrug fosgonimeton saw adverse events in clinical trials. Those with cancer, precancerous conditions, or compromised immune systems should avoid Dihexa. Read about risks in full.
There is no medically established human dose for Dihexa. Anecdotal community reports typically describe 10–30mg per day taken orally, with 10mg being a common starting point. Cycling protocols (e.g. 90 days on, 30 days off) are reported but not scientifically validated. Oral bioavailability is estimated at approximately 38%. Always consult a healthcare professional before considering any research compound. See the full dosage guide.
Fosgonimeton is a phosphate prodrug of Dihexa developed by Athira Pharma (formerly M3 Biotechnology). It is a different molecule with a different route of administration (subcutaneous injection) and was tested in Alzheimer's patients. Fosgonimeton failed its Phase 2 ACT-AD trial in 2022 and its Phase 2/3 LIFT-AD trial in September 2024. Importantly, fosgonimeton is NOT the same as raw Dihexa — the trial failures do not directly translate to conclusions about Dihexa itself. Read our full fosgonimeton analysis.
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