Lysergic acid 2,4-dimethylazetidide (
LA-SS-Az,
LSZ) is an
analog of
LSD developed by the team led by
David E. Nichols at
Purdue University. It was developed as a rigid analog of LSD with the diethylamide group constrained into an
azetidine ring in order to map the binding site at the
5-HT2A receptor. There are three possible
stereoisomers around the azetidine ring, with the
(S,S)-(+) isomer being the most active, slightly more
potent than LSD itself in drug discrimination tests using trained rats.