ALD-52, also known as 1-acetyl-LSD, is a chemical analogue of lysergic acid diethylamide (LSD).^[2] It was originally discovered by Albert Hofmann in 1957^[3][2] but was not widely studied until the rise in popularity of psychedelics in the 1960s.

Safety

In The Hallucinogens by Hoffer and Osmond (1967), ALD-52 is listed as having a lower (approximately ¹/₅) intravenous toxicity (in rabbits), a lower (approximately ¹/₈) pyretogenic effect, an equal psychological effect in humans, and double the “antiserotonin” effect as compared with LSD. Human experiments have not been well documented.