Ephenidine

Ephenidine (NEDPA, N-ethyl-1,2-diphenylethylamine) is a synthetic dissociative of the diarylethylamine class, the N-ethyl analog of diphenidine. It shares diphenidine's structural distinctiveness from the arylcyclohexylamine family (ketamine, PCP analogs), differing in the substitution of an ethyl group for diphenidine's methyl group on the nitrogen.

Community experience with ephenidine is modest but includes direct comparative reports with diphenidine — most notably a Reddit account of vaporizing both compounds ("Vaporizing MXP, ephenidine") that concluded "Neither was anywhere near as good as vaporizing diphenidine," suggesting that among diarylethylamines, diphenidine was preferred at least via that route of administration. A second community post describes vaporizing MXP (methoxphenidine, another diarylethylamine) alongside ephenidine, indicating these compounds are explored in similar contexts.

Ephenidine acts as an NMDA receptor antagonist (Ki = 66.4 nM — a value that places it in the same order of magnitude as ketamine, which has Ki ~2-5 μM, suggesting ephenidine is actually considerably more potent at the NMDA receptor). Its NMDA antagonism produces dissociation, analgesia, and the characteristic diarylethylamine experiential quality — described by community members as distinct from arylcyclohexylamines, often with less euphoria and a more unusual or "foreign" quality to the dissociation.