The specific enzymes responsible for the formation of O-H-LSD from LSD are unclear.[6][8][9][3] However, subsequent research found involvement of several cytochrome P450 enzymes.[10] O-H-LSD is thought to form from other LSD metabolites like 2-oxo-LSD and 3-hydroxy-LSD.[7][3][8][9][11]
O-H-LSD was first described in the scientific literature by at least the 1990s.[12][13] It started being sold online as an analytical standard by 2024.[5]
123Dolder PC, Schmid Y, Haschke M, Rentsch KM, Liechti ME (June 2015). "Pharmacokinetics and Concentration-Effect Relationship of Oral LSD in Humans". The International Journal of Neuropsychopharmacology. 19 (1) pyv072. doi:10.1093/ijnp/pyv072. PMC4772267. PMID26108222. In the present study, 13% of the orally administered LSD was recovered from urine as O-H-LSD within 24 hours. LSD is metabolized to O-H-LSD by cytochrome P450 enzymes, but the specific enzymes and mechanisms are unknown (Klette et al., 2000). To our knowledge, it is unknown whether O-H-LSD is pharmacologically active.
12Hintzen A, Passie T (10 June 2010). The Pharmacology of LSD. OUP/Beckley Foundation Press. p.29. ISBN978-0-19-958982-1. Fig. 2.7 Metabolites of LSD. [...]
123Meyer MR, Maurer HH (February 2011). "Absorption, distribution, metabolism and excretion pharmacogenomics of drugs of abuse". Pharmacogenomics. 12 (2): 215–233. doi:10.2217/pgs.10.171. PMID21332315. It is rapidly metabolized to the following five metabolites which have been identified in urine or blood from human users: N-demethyl-LSD (nor-LSD), 2-oxo-LSD, 2-oxo-3-hydroxy-LSD, 13-hydroxyLSD and 14-hydroxy-LSD [187–189]. The 13- and 14-hydroxy metabolites are additionally excreted as glucuronides [188]. However, 2-oxo-LSD may be an intermediate in the formation of 2-oxo-3-hydroxy-LSD. Following the incubation of LSD with HLM and hepatocytes, 2,3-dihydroxy-LSD could be identified [190]. 2-oxo-3-hydroxy-LSD was shown to be the main human urinary metabolite with concentrations four- to 40-times higher than that of LSD [187,188,191]. As concluded by Yu in his review on indolalkylamines, almost nothing is known regarding the contribution of specific drug-metabolizing enzymes to the production of individual LSD metabolites in humans.
123Meyer MR, Maurer HH (18 April 2012). "Drugs of Abuse (Including Designer Drugs)". Metabolism of Drugs and Other Xenobiotics. Wiley. pp.429–463. doi:10.1002/9783527630905.ch16. ISBN978-3-527-32903-8. It is metabolized to the following five metabolites: N-demethyl-LSD (nor-LSD), 2-oxo-LSD, 2-oxo-3-hydroxy-LSD, 13-hydroxy-LSD, and 14-hydroxy-LSD [72–74]. The 13- and 14-hydroxy metabolites are additionally excreted as glucuronides [74]. 2-Oxo-3-hydroxy-LSD was shown to be the main human urinary metabolite with concentrations 4–40 times higher than that of LSD [73–75]. In incubations of LSD with human liver microsomes and hepatocytes, 2,3-dihydroxy-LSD could be identified [71]. So far, the contribution and importance of specific enzymes in the formation of the LSD main metabolites such as 2-oxo-3-hydroxy-LSD still remains unclear.
12Luethi D, Hoener MC, Krähenbühl S, Liechti ME, Duthaler U (June 2019). "Cytochrome P450 enzymes contribute to the metabolism of LSD to nor-LSD and 2-oxo-3-hydroxy-LSD: Implications for clinical LSD use". Biochemical Pharmacology. 164: 129–138. doi:10.1016/j.bcp.2019.04.013. PMID30981875.
↑Libânio Osório Marta RF (August 2019). "Metabolism of lysergic acid diethylamide (LSD): an update". Drug Metabolism Reviews. 51 (3): 378–387. doi:10.1080/03602532.2019.1638931. PMID31266388. In vitro studies using liver microsomes and human cryopreserved hepatocytes showed that O-HLSD is a product of LSD biotransformation whose amount increases in a time-dependent manner. In the same study was detected another metabolite in a time-dependent manner upon incubation, the dihydroxy-LSD (Klette et al. 2000). Therefore, LSD is oxidized to 2-oxo-LSD, which undergoes subsequent hydroxylation to O-H-LSD. Although the formation of O-H-LSD may occur via intermediate metabolite dihydroxy-LSD (Figure 1) (Klette et al. 2002).
↑Vu-Duc T, Vernay A, Calanca A (December 1991). "Détection de l'acide lysergique diéthylamide (LSD) dans l'urine humaine: élimination, dépistage et confirmation analytique" [Detection of lysergic acid diethylamide in human urine: elimination, screening and analytical confirmation]. Schweizerische Medizinische Wochenschrift (in French). 121 (50): 1887–1890. PMID1759150.
↑Li Z, Goc-Szkutnicka K, McNally AJ, Pilcher I, Polakowski S, Vitone S, etal. (1997). "New synthesis and characterization of (+)-lysergic acid diethylamide (LSD) derivatives and the development of a microparticle-based immunoassay for the detection of LSD and its metabolites". Bioconjugate Chemistry. 8 (6): 896–905. doi:10.1021/bc9700594. PMID9404664.