Dihexa

Definition

Dihexa is a synthetic derivative of angiotensin IV, built to survive in the body long enough to reach the brain. It was developed in an academic laboratory as a candidate for dementia, and its proposed mechanism is not receptor agonism in the usual sense: it acts through the hepatocyte growth factor and c-Met system to promote synapse formation ^[1][2].

It is sold today as a nootropic. The gap between a metabolically stabilized angiotensin IV analogue designed for Alzheimer's disease research and a cognitive-enhancement product is the subject of this page.

Evidence

The preclinical record is genuine and small. The founding work evaluated metabolically stabilized angiotensin IV analogues as procognitive agents and identified this compound among them ^[1]; a follow-up established that the procognitive and synaptogenic effects depend on activation of the hepatocyte growth factor and c-Met system ^[2]; a 2021 study reported recovery of memory in a transgenic mouse model of Alzheimer's disease ^[3].

The human record does not exist. Across three name variants PubMed returns 18 indexed records in total, of which 9 carry the Humans subject heading, 0 the clinical-trial publication type, and 0 the randomized-controlled-trial type ^[4]. Eighteen records is the entire indexed literature for this compound, and the Humans-tagged nine are receptor and pathway work rather than administration to people.

FDA states the same thing from its own vantage point, and states it more starkly: it has not identified any human exposure data on drug products containing dihexa acetate administered via any route of administration ^[5]. Two instruments looking from opposite directions — a bibliographic census and a regulatory review — return the same answer, which is a stronger form of an absence claim than either produces alone.

Lawful access

There is no lawful United States supply route. Dihexa acetate was in Category 2 of FDA's interim section 503A bulks list and left it in April 2026 when the nomination was withdrawn by its nominators; it was not added to Category 1 and appears in no category of the list FDA published on May 14, 2026 ^[6].

The finding attached to it was never retracted. FDA continues to publish it: the agency lacks important information regarding any safety issues raised by dihexa acetate, including whether it would cause harm if administered to humans ^[5]. That is a different sentence from a finding of danger, and this index does not upgrade it into one. It is a statement that nobody knows, made by the body whose job it is to know.

Material sold under this name is research-use-only chemical supply, produced and sold outside pharmacy licensure, prescriber oversight, and pharmaceutical quality standards. The research-only page sets out what that position means for a buyer.

Related molecules

Dihexa is filed with the neuropeptides, where Semax and Selank carry a small foreign trial literature and DSIP an old one; this molecule has none at all, which makes it the class's clearest example of a marketed compound with an empty human record. The human trial record prints that zero beside every other count in the index.

Elsewhere in this index