Dihexa is a small peptide derivative of angiotensin IV, engineered as an HGF (hepatocyte growth factor) potentiator.

Mechanism — Stabilizes and amplifies HGF/c-Met signaling in the CNS, driving synaptogenesis and dendritic spine formation. Preclinical work suggests effects 7-10 orders of magnitude more potent than BDNF for spine formation.

Use case — Investigational for cognitive impairment, Alzheimer's, and neurorehabilitation. Research dosing 8-45 mg oral or transdermal daily. Oral bioavailability is one of its selling points.

Caveats — Human data essentially nonexistent. The HGF axis has growth-factor implications — long-term safety in oncology-naive populations is unknown.