Ephenidine, diphenidine, and methoxphenidine belong to the family of diarylethylamines that are psychoactive substances derived from lefetamine (N, N-di-methyl-1,2-diphenylethylamine, also called L-SPA). These dissociative anesthetic compounds act as potent and selective N-methyl-d-aspartate receptor antagonists and were recently classified as narcotic drugs in France. The available data suggest a significant risk of psychic and somatic complications. To obtain more information, this retrospective study analyzed all spontaneous notifications of serious cases of ephenidine, diphenidine, and methoxphenidine abuse collected by the French Addictovigilance Network from 2012 to 2016 and classified them as proven, probable, and possible. For each case, age, sex, concomitantly ingested substances, pattern of abuse of psychoactive drugs, and related complications (scored using the poisoning severity score) were collected. Eighteen cases were identified (one in 2013, five in 2015, and 12 in 2016) in 16 men (median age: 31.5 years [IQR 25-75% 27-34]). Ephenidine, diphenidine, and methoxphenidine were involved in four, seven, and 11 cases, respectively. No case was considered proven, 16 cases were considered possible, and two probable due to polysubstance abuse (co-ingestion of other new psychoactive substances). The reported clinical complications were minor in five cases, moderate in six cases, and serious in four cases, and included psychiatric, neurologic, and cardiovascular problems. This analysis indicates that the number of reported cases progressively increased from 2012 to 2016 and mainly concerned methoxphenidine. The addictive potential of these substances seems highly probable; but further investigations are needed to limit their harmful effects.
