Wikipedia
5-Methoxy-2-aminoindane (MEAI, 5-MeO-AI, or Chaperon) is a psychoactive small molecule belonging to the aminoindane class with a mechanism of action described by one patent as being mediated by binding to the dopamine D receptor. The work of Nichols and Johnson in the 1990s indicates that this class of molecules is non-neurotoxic.
It was first prepared by Schering AG in 1956. David Nutt and Amanda Feilding filed a patent application for the drug claiming that it gives people a pleasant intoxication as well as prevents binge drinking.
MEAI was available through grey market sources in 2011. At least 2 journalists tried it on themselves and reported to the public: Michael Slezak from New Scientist and Brie Traits from BBC3. Nutt has reported that he has also tried it himself.
The idea of alcohol substitution got public attention a year prior to the announcement of chaperon shortly after alcohol was implicated as the most harmful drug in Great Britain by a publication in The Lancet. Unlike suggested alcohol substitutes that came before it, chaperon innovates in that it can be consumed together with alcohol without ill effect.