Peptide profile

Dihexa

PNB-0408 / HGF Fragment / The Synaptogenesis Peptide

Cognitive

The most potent pro-cognitive compound identified to date — promotes synaptogenesis at concentrations 10 million times lower than BDNF.

Evidence Level

Anecdotal
Emerging
Moderate
Strong

Legal Status

Research Use Only

Dosage

10–50 mg per day oral or transdermal (dosing protocols still being established)

Route

oral capsule, transdermal application

How it works

A small orally active peptidomimetic derived from the hepatocyte growth factor (HGF) system, developed at Washington State University. Dihexa activates the HGF/c-MET signalling pathway, which directly promotes synaptogenesis (formation of new synaptic connections) and dendritic spine formation. Unlike BDNF, which requires continuous high concentrations to be effective, Dihexa is active at femtomolar concentrations. Animal studies demonstrate reversal of cognitive deficits in aged models to young-animal performance levels.

Research summary

Developed by Dr Joseph Harding and colleagues at Washington State University. Published in 2013 in Science Translational Medicine, demonstrating reversal of cognitive impairment in rat models at concentrations 10 million times lower than BDNF. No published human clinical trials as of 2025 — human use is entirely off-label based on pre-clinical data extrapolation. Considered advanced research territory. Users should approach under specialist physician supervision only.

Cycle duration

4–8 weeks on, 4 weeks off — long-acting effects persist after cessation

Stacks well with

These peptides complement Dihexa's mechanism and are commonly combined in protocols.

Cognitive
Moderate

Semax

The most potent BDNF-upregulating peptide — acute cognitive enhancement, neuroprotection, and stroke recovery support.

200–900 mcg per day (intranasal); 50–300 mcg subcutaneousView
Cognitive
Emerging

Selank

Russia's most studied anxiolytic peptide — reduces anxiety and enhances cognitive function without sedation or dependency.

250–500 mcg per dayView
LongevityCognitive
Moderate

NMN

The NAD+ precursor taken daily by both Andrew Huberman and Bryan Johnson — restores cellular energy production that declines with age.

500 mg – 2 g/day, taken in the morningView
LongevityFat Loss
Moderate

Ipamorelin + CJC-1295

The gold standard GH-releasing combination for anti-ageing, body recomposition, and sleep quality.

100–300 mcg of each peptide, before bedView

Free tool

Protein targets for your Dihexa

Protein requirements vary significantly by protocol goal and activity level.

80kg

144g

Daily total

48g

Per meal (3 meals)

1.8g/kg

Per kg bodyweight

Top sources to hit 144g daily

Chicken breast (cooked)~470g hits target
Whey protein (1 scoop ~30g)~180g hits target
Salmon fillet (cooked)~580g hits target
Eggs~21 eggs hits target
Greek yoghurt (200g serve)~8 serves hits target
Lean beef mince (cooked)~550g hits target

How this connects to your protocol

Amino acids are precursors to neurotransmitters including dopamine, serotonin, and acetylcholine. Adequate protein supports the cognitive benefits of your nootropic protocol.

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Targets are evidence-based estimates. Consult your practitioner for personalised advice.

Risks & side effects

Very limited human safety data — pre-clinical research only at this stage
Precise human dosing not established — extreme caution required
Long-acting mechanism means effects and potential adverse events persist after cessation
Research-grade only — requires specialist medical supervision
Theoretical oncological concerns from HGF pathway activation — unconfirmed in practice

How to access in Australia

Check with an AHPRA-registered practitioner for the current legal pathway to access this compound in Australia.

Find a prescriber

Australian clinics that prescribe Dihexa or treat related goals.

Rx

Thrive Rx

Telehealth Clinic
4.8(312)

Australia's most thorough longevity and peptide clinic — blood panel first, protocol second.

$199–$599 AUD / month Australia-wide
AHPRA-registered clinicians
Comprehensive blood panel included in membership
Ongoing biomarker tracking every 6 months
Higher price point than GLP-1 only clinics
Requires full health assessment before any prescription
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Medical disclaimer

The information on this page is for educational purposes only and does not constitute medical advice. All peptide and supplement therapies should be discussed with an AHPRA-registered medical practitioner before use. ProtocolHub does not prescribe, dispense, or supply any therapeutic goods. Always consult a qualified healthcare professional before starting any new health protocol.

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