PNB-0408, ATH-1001, N-hexanoic-Tyr-Ile-(6)-aminohexanoic amide
A modified three-residue analog of angiotensin IV, built to survive digestion and reach the brain. It is reported to amplify hepatocyte growth factor (HGF) signalling at its receptor, c-Met, which in rats built new synapses and improved maze learning.
Category 2 is FDA’s list of bulk substances that may present significant safety risks in compounding. The 503A bulks list adds substances that pharmacies may compound with. Advisory committee votes are advice; FDA makes the final decision. Sport status follows the WADA Prohibited List in force since January 1, 2026; athletes should confirm with their anti-doping organization. Checked October 5, 2026. Status of every compound.
Dihexa was built from angiotensin IV, a fragment of the blood-pressure hormone angiotensin, and was reported to boost signaling by hepatocyte growth factor (HGF), a protein that drives tissue growth and repair, through its receptor, c-Met; in rats this was linked to new nerve connections and better maze learning. The two papers that set out this mechanism were retracted in 2025, and the main rat paper carries a notice of concern. In people, only fosgonimeton, an injected form the body converts into dihexa, has been tested.
AnimalMainly from cell and animal studies; not shown in people.
It isn’t known whether it acts through HGF and c-Met at all, how much reaches the brain after a dose by mouth, or whether long-term use affects cancer risk.
5–20 mg by mouth once daily, in short blocks. No dose has been tested in people; these figures are scaled from a 2 mg/kg rat dose.
LIFT-AD
Fosgonimeton, the injected prodrug of this molecule: 40 mg once daily under the skin. A 70 mg arm was dropped part-way for tolerability.
No set cycle, shown over 26 weeks
The ways Dihexa is most often run, each tagged with where it comes from.
The usual community route, chosen because rats absorbed it by mouth. The milligram figures are scaled from rat doses, not measured in people.
Used because the powder won’t dissolve in water. DMSO also carries whatever else it touches through the skin, and how much peptide gets in is unknown.
LIFT-AD, 287 people in the main analysis. The injection released this molecule into the blood, and it did not improve thinking or daily function versus placebo.
Taken by mouth, so there are no injection sites. Some guides apply it in DMSO to thin skin on the forearms. In the trials the prodrug went under the skin, and injection-site reactions were its main side effect.
No published guidance. Skip the missed dose and take the next one as usual; don’t double up.
Vivid dreams are the most consistent thing users describe, along with headaches at higher amounts.
CommunityClaims of sharper memory and focus rest on user reports. A sizeable share of users report no change at all.
CommunityThinking (ADAS-Cog11) differed from placebo by 0.70 points in fosgonimeton’s favor (p=0.35) and daily function (ADCS-ADL23) by 0.67 points (p=0.61). Neither reached significance.
TrialVivid dreams or broken sleep
The effect users report most often. Guides move the dose to the morning.
Headache
Reported at higher amounts and with DMSO preparations. Lower the amount or stop.
No human safety data for dihexa itself
There is no Phase 1 study of it, so no side effect list and no rates exist. The prodrug’s trials mainly showed injection-site reactions.
Unknown cancer risk, since HGF and c-Met are a cancer pathway
No study has looked at this. A current, past or suspected cancer is a clear reason to avoid it.
Stomach upset by mouth, or skin irritation from DMSO
Reported as mild and passing. Stop the topical if the skin stays red or burns.
Stop and get medical help for chest pain, fainting, a sudden severe headache or change in vision, or hives with swelling of the face or throat. Have any new lump, unexplained weight loss or night sweats checked by a doctor.
No product label covers Dihexa, so these come from human studies and from precautions based on how it works. Most important first.
Trial: seen in human studies, or a group those studies left out. Precaution: follows from how it works or from a related drug, and hasn’t been tested. This isn’t a complete list: a pharmacist or doctor can check a specific medicine or condition.
3 key published human studies, with how many people took part. Animal studies aren’t listed here.
The main endpoint, a combined score of thinking and daily function, differed from placebo by −0.08 (p=0.70); thinking and function alone also missed significance. 14.2% stopped for side effects vs 4.6% on placebo, mostly injection-site reactions.
Porsteinsson et al., J Alzheimers Dis Rep 2025, PMID 41393340
The main endpoint, the delay of a brain signal called P300, changed by −6.02 milliseconds across both doses, which was not significant.
Athira Pharma results announcement, June 22, 2022, and conference presentation; no PubMed record found
Safe and well tolerated at every dose, with injection-site reactions the main side effect; the active molecule had a half-life of about 1.5 hours, and P300 delay moved toward normal in the 11 people with Alzheimer’s (p=0.027).
Hua et al., J Alzheimers Dis 2022, PMID 35180125
No study has given dihexa itself to a person. Its injected prodrug was tested in 88 people for up to 9 days, then in 26-week Alzheimer’s trials, where it missed its main goals. Dosing by mouth, the amounts people take, long-term safety and cancer risk are untested, and the rat work behind its mechanism has been partly retracted.
Dihexa hardly dissolves in water, so vials sold for injection are usually mixed with DMSO rather than bacteriostatic water. The prodrug used in the trials, fosgonimeton, was a ready-made solution for injection, not a powder to mix.
Every compound side by side: the half-life chart and the storage chart.
A modified three-residue analog of angiotensin IV, built to survive digestion and reach the brain. It is reported to amplify hepatocyte growth factor (HGF) signalling at its receptor, c-Met, which in rats built new synapses and improved maze learning.
Dihexa was built from angiotensin IV, a fragment of the blood-pressure hormone angiotensin, and was reported to boost signaling by hepatocyte growth factor (HGF), a protein that drives tissue growth and repair, through its receptor, c-Met; in rats this was linked to new nerve connections and better maze learning. The two papers that set out this mechanism were retracted in 2025, and the main rat paper carries a notice of concern. In people, only fosgonimeton, an injected form the body converts into dihexa, has been tested. It isn’t known whether it acts through HGF and c-Met at all, how much reaches the brain after a dose by mouth, or whether long-term use affects cancer risk.
Not approved as a drug in the US or EU, and not approved anywhere. The only version that reached trials was fosgonimeton, an injected prodrug of this molecule, which missed its endpoints in a Phase 2/3 Alzheimer’s trial reported in September 2024. The company behind it renamed itself in January 2026 and moved to cancer drugs; fosgonimeton no longer appears in its pipeline. Dihexa acetate was nominated for the 503A compounding list and the nomination was withdrawn, so it is no longer in Category 2 as of April 2026 and it is not cleared for compounding either. FDA’s note on it says the agency identified no human exposure data for dihexa acetate by any route of administration.
From community reports, not established: 5–20 mg by mouth once daily, in short blocks. No dose has been tested in people; these figures are scaled from a 2 mg/kg rat dose. From human studies (LIFT-AD): Fosgonimeton, the injected prodrug of this molecule: 40 mg once daily under the skin. A 70 mg arm was dropped part-way for tolerability. These are the amounts sources reference, not recommendations.
By mouth: capsules, or loose powder weighed into a capsule. Morning. Guides avoid late doses because of reports of vivid dreams and broken sleep. There’s nothing to mix or measure with a syringe.
No product label covers Dihexa, so these come from human studies and from precautions based on how it works. Anyone with active or past cancer: HGF and c-Met drive growth and spread in many cancers, and dihexa is claimed to boost that signal. Its injected prodrug’s Alzheimer’s trial excluded cancer within the past 3 years. Heart disease or high or low blood pressure: The prodrug’s Alzheimer’s trial excluded recent heart attack or unstable angina (worsening chest pain), significant rhythm problems, high blood pressure and low blood pressure with symptoms, so it is untested in these groups. Kidney or liver impairment: The same trial excluded moderate-to-severe kidney disease and liver impairment, so how the body handles the drug in these groups is unknown. The “Who should avoid it” section lists 3 more groups.
About 1.5 hours, measured in human studies. Plasma half-life of the active molecule, called ATH-1001 in the trials, after its prodrug fosgonimeton was injected under the skin in 88 people. A slower tail with a half-life near 5 hours appeared now and then at 40 mg and above. Nobody has measured it after a dose by mouth.
Before mixing: Freezer (about −20 °C) for long-term storage, dry and away from light. After mixing: In DMSO or a cream: refrigerate and use within a few weeks. This is common practice; no product label covers it.
Probably. Not named on the 2026 list. S2.3 covers growth factors and growth factor modulators and names hepatocyte growth factor (HGF) itself, but dihexa is not HGF, and S2.3’s catch-all reaches modulators affecting muscle, tendon or ligament, vascularization, energy use, regenerative capacity or fiber type switching, which a brain-synapse claim does not clearly match. An anti-doping body could still argue it belongs there as an HGF modulator. Either way S0 applies, because no health authority anywhere approves a medicine containing it, so it is banned at all times.
Yes. The human studies section lists 3 published studies. The largest, from 2025, included 287 people. The main endpoint, a combined score of thinking and daily function, differed from placebo by −0.08 (p=0.70); thinking and function alone also missed significance. 14.2% stopped for side effects vs 4.6% on placebo, mostly injection-site reactions.
For the protocol details
For how it works, who should avoid it and the limits of the evidence
Doses tagged Community come from public dosing guides and user reports, checked against at least two of them. Those sites aren’t named here because many of them sell peptides or earn commissions on them.