nasal mood

why it works

Three compounds, three different confidence levels, and levelling them would be the easy mistake.

PE-22-28 is a spadin analogue that blocks TREK-1, a two-pore potassium channel whose deletion produces a depression-resistant phenotype in mice. The interesting claim is speed: antidepressant-like effects within days rather than weeks in rodent work, which is the territory ketamine opened and which very few mechanisms reach. ⚠️ There is no human data. Not thin human data; none.

Nemifitide, or INN-00835, is a pentapeptide derivative of melanocyte-inhibiting factor and is the best-evidenced compound here by some distance because it actually reached phase II trials for major depression. ⚠️ Report that as it reads: it showed signal in those trials and development did not continue, and the reasons a programme stops are frequently commercial rather than scientific, which cuts both ways.

Epitalon is the odd one out and is marked optional for that reason. It is a four-amino-acid peptide from the Russian bioregulator programme, associated with telomerase and pineal signalling claims. ⚠️ It is the compound on this page where literature and reputation diverge most: much of the supporting work is older Russian material that is hard to obtain and harder to appraise, and the longevity claims attached to it far exceed what those papers show. Its inclusion in a mood stack rests on the pineal and circadian angle rather than on antidepressant data, and saying so is more useful than implying otherwise.

how they work together

The route is the organising idea, so it is worth saying why it matters rather than treating nasal as a convenience. Peptides are poorly absorbed orally because the gut degrades them, and the intranasal route both bypasses much of first-pass metabolism and offers a path toward the central nervous system along the olfactory and trigeminal nerves. That is the reason these three are grouped.

⚠️ THE DELIVERY CLAIM IS DOING REAL WORK IN THE RATIONALE, WHICH MEANS IT DESERVES SCRUTINY. Nose-to-brain transport in humans is established for some molecules and inferred for others, and it is not a general property of putting something in the nose. The honest position is that the route improves bioavailability reliably and improves brain exposure variably.

⚠️ AND FOR TWO OF THESE THREE, THE NASAL ROUTE IS PRACTICE RATHER THAN LITERATURE. A PubMed sweep run across the peptide catalogue found no published study that has ever given PE-22-28 or nemifitide intranasally, in any species. PE-22-28's single named paper dosed mice by intraperitoneal injection and by oral gavage; every nemifitide human trial used subcutaneous injection. Epithalon is the one of the three whose entry carries intranasal evidence. Nothing was removed for this, and it does not mean the route fails; it means the delivery rationale above is reasoning from peptide chemistry in general rather than from these two compounds in particular, and each entry now says so on its own page.

Mechanically the three do not converge. PE-22-28 blocks a potassium channel, nemifitide is a melanocyte-inhibiting-factor derivative with an unclear mechanism, and epitalon's angle is circadian. What they share is the route and the target, not a pathway.

what it feels like

PE-22-28's animal literature is specifically about speed, with antidepressant-like effects in days rather than weeks; whether that translates is unknown, because no human has been studied.

Nemifitide's trial reports describe onset over one to two weeks in the populations studied, which is fast for an antidepressant and slow compared with what its animal cousins suggested.

Epitalon is most commonly reported as affecting sleep rather than mood, which is consistent with the pineal framing and is the honest reason it is marked optional here.