ALD-52 or N-acetyl-LSD, is a chemical analogue of LSD (Lysergic Acid Diethylamide). It was originally discovered by Albert Hofmann but was not widely studied until the rise in popularity of psychedelics in the 1960s.
In TiHKAL, Shulgin touches briefly on ALD-52 in entry 26, LSD. His writings are vague, second hand accounts, saying doses in the 50-175µg range have resulted in various conclusions. One found that there was less visual distortion than with LSD and it seems to produce less anxiety and was somewhat less potent than LSD. Another report claimed it was more effective in increasing blood pressure. Yet another could not tell them apart.
It has the same characteristics as LSD, but supposedly “without the anxiety, tenseness, and other problems inherent to it”.
In The Hallucinogens by Hoffer and Osmond (1967), ALD-52 (D,L-Acetyllysergic acid diethylamide) 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 man, and double the antiserotonin effect as compared with LSD.
It is possible ALD-52 was the active chemical in the “Orange Sunshine” LSD that was widely available in California through 1968 and 1969. The Sonoma County underground chemistry lab of Tim Scully and Nicholas Sand was the source for “Orange Sunshine.” It was shut down by the police, and Scully was arrested and prosecuted. This resulted in the first drug analogue trial, where Scully claimed that he and his partners did nothing wrong, because they were producing ALD-52 which was not an illicit drug. However, as the prosecution claimed, there were problems with such a rationale: first, ALD-52 readily undergoes hydrolysis to LSD, and second, the synthesis of ALD-52 required LSD (this was based on the methods available in the scientific literature at the time). Scully was convicted and served time in prison.
The Chemistry of ALD-52
ALD-52 was first synthesized by Franz Troxler and Albert Hofmann in 1957.1 It belongs to the ergoline family of compounds which includes LSD. The chemical structure of ALD 52 differs from LSD by having an acetyl group on the nitrogen atom in the indole ring.
The Pharmacology of ALD-52
Research conducted decades ago found that ALD-52 was psychoactive in humans.2–5 Additional work at the time showed its potency about equivalent to that of LSD.6
A recent study determined Ki values for ALD-57 of 1,054 nM, 174 nM, and 10.2 nM, at serotonin 5-HT1A, 5-HT2A, and 5-HT2C, respectively.7 Receptor activity studies indicated that ALD-52 is a very weak partial agonist at the human 5-HT2A receptor compared to LSD, but it did induce the head-twitch response in mice. However, ALD-52 showed no agonist activity at 5-HT2A, and 5-HT2C despite showing comparatively high affinity those receptors compared to LSD.