1P-LSD or 1-Propionyl-LSD in the form of blotters is a new designer drug that replaces LSD and has all of its properties. 1P-LSD is reminiscent of the MLD-41 and ALD-52 indole prodrug. 1-Propionyl-d-lysergic acid diethylamide (also known as 1P-LSD) is a novel semi-synthetic psychedelic substance of the lysergamide class. 1P-LSD is closely related to LSD and is reported to produce near-identical effects. Little is known about the pharmacology of 1P-LSD, but it likely produces its psychedelic effects by acting on serotonin receptors in the brain.