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.

[2][3] 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.

[4] There have been several unconfirmed reports of lysergic acid 2,4-dimethylazetidide being synthesized in illicit laboratories and distributed on blotter paper or in liquid solution under names such as "diazedine" and "λ".

[7] The UK Home office accepted this advice and announced a ban of the substance to be enacted on 6 January 2015 as part of The Misuse of Drugs Act 1971 (Amendment) (No.