2-Iodo-LSD
chemical compound
2-Iodo-LSD (IOL) is a putatively non-hallucinogenic serotonin receptor modulator of the lysergamide family related to 2-bromo-LSD (BOL-148) and lysergic acid diethylamide (LSD). It is the 2-iodo derivative of LSD.
Use and effects
According to Alexander Shulgin in his 1997 book TiHKAL (Tryptamines I Have Known and Loved), it is unknown whether 2-iodo-LSD has ever been tested in humans.
Pharmacology
Pharmacodynamics
2-Iodo-LSD shows high affinity for the serotonin 5-HT2 receptors and also shows affinity for other serotonin receptors as well as for the dopamine and adrenergic receptors. In contrast to LSD, but similarly to 2-bromo-LSD, 2-iodo-LSD is predominantly antagonistic at the serotonin 5-HT2A and 5-HT2C receptors and is described as non-hallucinogenic. The drug has about 57.4% of the antiserotonergic activity of LSD in the isolated rat uterus in vitro, whereas 2-bromo-LSD has about 103% of LSD's potency in this assay.
Radiolabeling
[125I]2-Iodo-LSD, a radiolabeled analogue of 2-iodo-LSD, has been used as a radioligand for serotonin 5-HT2 receptors. In addition, radiolabeled derivatives of 2-iodo-LSD, such as 1-methyl-2-[125I]iodo-LSD ([125I]-MIL) and 1-ethyl-2-[125I]iodo-LSD ([125I]-EIL), have been developed for use as presumably non-hallucinogenic agents in imaging of serotonin receptors.
History
2-Iodo-LSD was described in the scientific literature by Albert Hofmann and colleagues by 1956.
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Datasets, specimens, observations and peer-reviewed methods provide the appropriate test for the technical claims summarized here. The source revision retrieved here is dated Aug 7, 2026. The linked authority identifier is Q82938801. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1997 and 1956.
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This entry incorporates text from “2-Iodo-LSD” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.