OPEN Foundation

M. Hoener

Cytochrome P450 enzymes contribute to the metabolism of LSD to nor-LSD and 2-oxo-3-hydroxy-LSD: Implications for clinical LSD use

April 11, 2019 / Chemistry, LSD, Neuroscience, Other subjects, Papers, Psychopharmacology, Psychotherapy / By / , , , ,

Abstract

In recent years, experimental research on lysergic acid diethylamide (LSD) in humans has gained new momentum. In humans, LSD is metabolized rapidly into several metabolites but knowledge of the involved metabolizing enzymes is limited. The aim of the current study was to identify the cytochrome P450 (CYP) isoforms involved in the metabolism of LSD to 6-norlysergic acid diethylamide (nor-LSD) and 2-oxo-3-hydroxy-LSD (O-H-LSD) in vitro, in order to evaluate potential effects of enzyme polymorphisms or prescription drugs on LSD pharmacokinetics. Additionally, interactions of LSD and both metabolites with 5-hydroxytryptamine (5-HT) receptors were assessed. LSD was incubated with human liver microsomes over 4 h and the production of nor-LSD and O-H-LSD was quantified by liquid chromatography tandem mass spectrometry. Metabolism was inhibited by the addition of specific CYP inhibitors. Additionally, recombinant CYPs were used to verify the inhibition results obtained with microsomes and induction of metabolism was investigated in human hepatocyte-derived cells. Radioligand binding and calcium mobilization assays were used to determine 5-HT receptor affinities and activities, respectively. Human liver microsomes displayed minor metabolite formation (<1% metabolized) over 4 h. CYP2D6, 2E1, and 3A4 significantly contributed to the formation of nor-LSD, and CYP1A2, 2C9, 2E1, and 3A4 were significantly involved in the formation of O-H-LSD. These findings could be verified using recombinant CYPs. Enzyme induction with rifampicin distinctly increased the formation of both metabolites, whereas treatment with omeprazole only slightly increased formation of nor-LSD. LSD and nor-LSD were pharmacologically active at the 5-HT1A, 5-HT2A, 5-HT2B, and 5-HT2C receptors. Nor-LSD mainly differed from the parent compound by having a lower affinity to the 5-HT2C receptor. O-H-LSD displayed substantially weaker affinity and activity at serotonergic receptors in comparison to LSD. To conclude, human liver microsomes converted only small amounts of LSD to nor-LSD and O-H-LSD but several CYPs significantly contributed. Genetic polymorphisms and drug interactions could therefore influence pharmacokinetics and pharmacodynamics of LSD. Nor-LSD likely has hallucinogenic activity similar to LSD, whereas O-H-LSD is inactive. Drug-drug interaction studies in humans are required to further assess the clinical relevance of these findings.

Luethi, D., Hoener, M. C., Krähenbühl, S., Liechti, M. E., & Duthaler, U. (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., 10.1016/j.bcp.2019.04.013
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Monoamine receptor interaction profiles of 4-thio-substituted phenethylamines (2C-T drugs)

July 15, 2017 / Neuroscience, New substances, Other substances, Papers, Psychopharmacology / By / , , ,

Abstract

BACKGROUND:
4-Thio-substituted phenethylamines (2C-T drugs) are potent psychedelics with poorly defined pharmacological properties. Because of their psychedelic effects, 2C-T drugs are sometimes sold as new psychoactive substances (NPSs). The aim of the present study was to characterize the monoamine receptor and transporter interaction profiles of a series of 2C-T drugs.
METHODS:
We determined the binding affinities of 2C-T drugs at monoamine receptors and transporters in human cells that were transfected with the respective receptors or transporters. We also investigated the functional activation of serotonergic 5-hydroxytryptamine 2A (5-HT2A) and 5-HT2B receptors, activation of human trace amine-associated receptor 1 (TAAR1), and inhibition of monoamine uptake transporters.
RESULTS:
2C-T drugs had high affinity for 5-HT2A and 5-HT2C receptors (1-54 nM and 40-350 nM, respectively). With activation potencies of 1-53 nM and 44-370 nM, the drugs were potent 5-HT2A receptor and 5-HT2B receptor, respectively, partial agonists. An exception to this were the benzylthiophenethylamines, which did not potently activate the 5-HT2B receptor (EC50 > 3000 nM). Furthermore, the compounds bound to serotonergic 5-HT1A and adrenergic receptors. The compounds had high affinity for the rat TAAR1 (5-68 nM) and interacted with the mouse but not human TAAR1. The 2C-T drugs did not potently interact with monoamine transporters (Ki > 4000 nM).
CONCLUSION:
The receptor binding profile of 2C-T drugs predicts psychedelic effects that are mediated by potent 5-HT2 receptor interactions.
Luethi, D., Trachsel, D., Hoener, M. C., & Liechti, M. E. (2017). Monoamine receptor interaction profiles of 4-thio-substituted phenethylamines (2C-T drugs). Neuropharmacology. 10.1016/j.neuropharm.2017.07.012
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Receptor interaction profiles of novel psychoactive tryptamines compared with classic hallucinogens

May 20, 2016 / Neuroscience, New substances, Other substances, Papers, Psychopharmacology, Publications / By / , , ,

Abstract

The present study investigated interactions between the novel psychoactive tryptamines DiPT, 4-OH-DiPT, 4-OH-MET, 5-MeO-AMT, and 5-MeO-MiPT at monoamine receptors and transporters compared with the classic hallucinogens lysergic acid diethylamide (LSD), psilocin, N,N-dimethyltryptamine (DMT), and mescaline. We investigated binding affinities at human monoamine receptors and determined functional serotonin (5-hydroxytryptamine [5-HT]) 5-HT2A and 5-HT2B receptor activation. Binding at and the inhibition of human monoamine uptake transporters and transporter-mediated monoamine release were also determined. All of the novel tryptamines interacted with 5-HT2A receptors and were partial or full 5-HT2A agonists. Binding affinity to the 5-HT2A receptor was lower for all of the tryptamines, including psilocin and DMT, compared with LSD and correlated with the reported psychoactive doses in humans. Several tryptamines, including psilocin, DMT, DiPT, 4-OH-DiPT, and 4-OH-MET, interacted with the serotonin transporter and partially the norepinephrine transporter, similar to 3,4-methylenedioxymethamphetamine but in contrast to LSD and mescaline. LSD but not the tryptamines interacted with adrenergic and dopaminergic receptors. In conclusion, the receptor interaction profiles of the tryptamines predict hallucinogenic effects that are similar to classic serotonergic hallucinogens but also MDMA-like psychoactive properties.

Rickli, A., Moning, O. D., Hoener, M. C., & Liechti, M. E. (2016). Receptor interaction profiles of novel psychoactive tryptamines compared with classic hallucinogens. European Neuropsychopharmacology. http://dx.doi.org/10.1016/j.euroneuro.2016.05.001

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30 April - Q&A with Rick Strassman

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