title: Effects of monoamine oxidase inhibitor and cytochrome P450 2D6 status on 5-methoxy-N,N-dimethyltryptamine metabolism and pharmacokinetics.
abstract: 5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a natural psychoactive indolealkylamine drug that has been used for recreational purpose. Our previous study revealed that polymorphic cytochrome P450 2D6 (CYP2D6) catalyzed 5-MeO-DMT O-demethylation to produce active metabolite bufotenine, while 5-MeO-DMT is mainly inactivated through deamination pathway mediated by monoamine oxidase (MAO). This study, therefore, aimed to investigate the impact of CYP2D6 genotype/phenotype status and MAO inhibitor (MAOI) on 5-MeO-DMT metabolism and pharmacokinetics. Enzyme kinetic studies using recombinant CYP2D6 allelic isozymes showed that CYP2D6.2 and CYP2D6.10 exhibited 2.6- and 40-fold lower catalytic efficiency (V(max)/K(m)), respectively, in producing bufotenine from 5-MeO-DMT, compared with wild-type CYP2D6.1. When co-incubated with MAOI pargyline, 5-MeO-DMT O-demethylation in 10 human liver microsomes showed significantly strong correlation with bufuralol 1'-hydroxylase activities (R(2)=0.98; P<0.0001) and CYP2D6 contents (R(2)=0.77; P=0.0007), whereas no appreciable correlations with enzymatic activities of other P450 enzymes. Furthermore, concurrent MAOI harmaline sharply reduced 5-MeO-DMT depletion and increased bufotenine formation in human CYP2D6 extensive metabolizer hepatocytes. In vivo studies in wild-type and CYP2D6-humanized (Tg-CYP2D6) mouse models showed that Tg-CYP2D6 mice receiving the same dose of 5-MeO-DMT (20mg/kg, i.p.) had 60% higher systemic exposure to metabolite bufotenine. In addition, pretreatment of harmaline (5mg/kg, i.p.) led to 3.6- and 4.4-fold higher systemic exposure to 5-MeO-DMT (2mg/kg, i.p.), and 9.9- and 6.1-fold higher systemic exposure to bufotenine in Tg-CYP2D6 and wild-type mice, respectively. These findings indicate that MAOI largely affects 5-MeO-DMT metabolism and pharmacokinetics, as well as bufotenine formation that is mediated by CYP2D6.
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, The State University of New York, 541 Cooke Hall, Buffalo, NY 14260-1200, USA.
authors.forename: Hong-Wu
authors.initials: HW
authors.lastname: Shen
authors.forename: Chao
authors.initials: C
authors.lastname: Wu
authors.forename: Xi-Ling
authors.initials: XL
authors.lastname: Jiang
authors.forename: Ai-Ming
authors.initials: AM
authors.lastname: Yu
mesh_terms: D000818:Animals; D019540:Area Under Curve; D002027:Bufotenin / Q000378:metabolism; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005838:Genotype; D006207:Half-Life; D006246:Harmaline / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008732:Methoxydimethyltryptamines / Q000378:metabolism* / Q000493:pharmacokinetics* / Q000494:pharmacology; D008745:Methylation / Q000187:drug effects; D051379:Mice; D008822:Mice, Transgenic; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism; D008995:Monoamine Oxidase / Q000378:metabolism; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology*; D010293:Pargyline / Q000378:metabolism; D010641:Phenotype; D011110:Polymorphism, Genetic / Q000187:drug effects; D011619:Psychotropic Drugs / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D007527:Isoenzymes; D008732:Methoxydimethyltryptamines; D008996:Monoamine Oxidase Inhibitors; D011619:Psychotropic Drugs; D002027:Bufotenin; D003577:Cytochrome P-450 Enzyme System; D010293:Pargyline; D006246:Harmaline; D019389:Cytochrome P-450 CYP2D6; C043872:bufuralol 1'-hydroxylase; D008995:Monoamine Oxidase