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Mosca A, Chiappini S, Miuli A, Mancusi G, Santovito MC, Di Carlo F, Pettorruso M, Corkery JM, Canessa C, Martinotti G, Di Giannantonio M. Ibogaine/Noribogaine in the Treatment of Substance Use Disorders: A Systematic Review of the Current Literature. Curr Neuropharmacol 2023; 21:2178-2194. [PMID: 36263479 PMCID: PMC10556383 DOI: 10.2174/1570159x21666221017085612] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/05/2022] [Accepted: 10/06/2022] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Ibogaine and noribogaine are psychedelic substances with dissociative properties naturally occurring in plants of the Apocynaceae family. Research has shown their efficacy in treating substance use disorders (SUD), particularly in opiate detoxification, but their efficacy and toxicity are still unclear. OBJECTIVE This review aims to assess the anti-addictive role of ibogaine and evaluate its side effects. METHODS A systematic literature review was conducted on the 29th of November 2021 using PubMed, Scopus and Web of Science databases through the following search strategy: ("Ibogaine" OR "Noribogaine") AND ("SUD" OR "substance use disorder" OR "craving" OR "abstinence" OR "withdrawal" OR "addiction" OR "detoxification") NOT animal NOT review NOT "vitro." The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was followed for data gathering purposes. Research methods were registered on PROSPERO (CRD42021287034). RESULTS Thirty-one articles were selected for the systematic revision, and two were considered for analysis. The results were organised according to the type of study: case reports/case series, randomised- controlled trials (RCTs), open-label, survey and observational studies. The main outcomes were related to the anti-addictive effect of ibogaine and its cardiac toxicity. A meta-analysis of side effects was conducted using RevMan 5.4 software, showing a significant risk of developing headaches after ibogaine/noribogaine treatment. CONCLUSION The results show some efficacy of ibogaine in the treatment of SUDs, but its cardiotoxicity and mortality are worrying. Further studies are needed to assess its therapeutic efficacy and actual safety.
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Affiliation(s)
- Alessio Mosca
- Department of Neurosciences, Imaging and Clinical Sciences, Università degli Studi G. D’Annunzio, Chieti-Pescara, 66100, Italy
| | - Stefania Chiappini
- Department of Neurosciences, Imaging and Clinical Sciences, Università degli Studi G. D’Annunzio, Chieti-Pescara, 66100, Italy
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, University of Hertfordshire, Hertfordshire, AL10 9AB, UK
| | - Andrea Miuli
- Department of Neurosciences, Imaging and Clinical Sciences, Università degli Studi G. D’Annunzio, Chieti-Pescara, 66100, Italy
| | - Gianluca Mancusi
- Department of Neurosciences, Imaging and Clinical Sciences, Università degli Studi G. D’Annunzio, Chieti-Pescara, 66100, Italy
| | - Maria Chiara Santovito
- Department of Neurosciences, Imaging and Clinical Sciences, Università degli Studi G. D’Annunzio, Chieti-Pescara, 66100, Italy
| | - Francesco Di Carlo
- Department of Neurosciences, Imaging and Clinical Sciences, Università degli Studi G. D’Annunzio, Chieti-Pescara, 66100, Italy
| | - Mauro Pettorruso
- Department of Neurosciences, Imaging and Clinical Sciences, Università degli Studi G. D’Annunzio, Chieti-Pescara, 66100, Italy
| | - John M. Corkery
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, University of Hertfordshire, Hertfordshire, AL10 9AB, UK
| | | | - Giovanni Martinotti
- Department of Neurosciences, Imaging and Clinical Sciences, Università degli Studi G. D’Annunzio, Chieti-Pescara, 66100, Italy
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, University of Hertfordshire, Hertfordshire, AL10 9AB, UK
| | - Massimo Di Giannantonio
- Department of Neurosciences, Imaging and Clinical Sciences, Università degli Studi G. D’Annunzio, Chieti-Pescara, 66100, Italy
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Abstract
Ibogaine is a psychotropic indole alkaloid extracted from the roots of the Tabernanthe iboga shrub from the Apocynaceae family. Depending on the taken dose, it can lead to stimulant effects, euphoria, visual and auditory hallucinations, along with auditory, olfactory, and gustatory synesthesia. In addition to its historical usage in spiritual rituals of African tribes, these days iboga extract presents a prohibited, alternative drug widely used as a part of addiction treatment. Ibogaine used in opioid withdrawal is associated with serious side effects and sudden deaths. Besides its main use as an anti-addiction medication in alternative medicine, in moderate doses (from 100mg to 1g) ibogaine most commonly causes a "trance-like state".In this paper, we report the case of a heroin addict who died suddenly 5-12 hours after oral ingestion of powder labeled Tabernanthe iboga which had been bought online and used in the process of detoxification during an addiction treatment. The man was found dead in a rented apartment, where he was undergoing the addiction treatment.External examination revealed no lesions other than nonspecific injuries on the legs. The autopsy showed congestion of internal organs and pulmonary edema. Histopathological analysis of the heart showed neither macroscopic nor microscopic abnormalities. The concentration of ibogaine was 3.26mg/L. Moreover, systematic toxicological analyses of biological samples showed the presence of morphine and codeine. These data suggest that death, which occurred unnaturally after initiation of the "treatment", was probably the result of the cardiovascular effects caused by the ibogaine powder.The presented case highlights the worldwide problem of various products being widely available over the internet and the danger associated with consumption thereof.
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Allard S, Le Daré B, Allard PM, Morel I, Gicquel T. Comparative molecular networking analysis of a Rauwolfia plant powder and biological matrices in a fatal ingestion case. Forensic Toxicol 2020. [DOI: 10.1007/s11419-020-00531-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Corkery JM. Ibogaine as a treatment for substance misuse: Potential benefits and practical dangers. PROGRESS IN BRAIN RESEARCH 2018; 242:217-257. [PMID: 30471681 DOI: 10.1016/bs.pbr.2018.08.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ibogaine is an indole alkaloid found in the root bark of the Iboga shrub native to west Africa possessing hallucinogenic properties. For centuries it has been used in religious ceremonies and to gain spiritual enlightenment. However, since the early 1960s, its apparent ability to reduce craving for psychoactive substances including alcohol, cocaine, methamphetamine, opiates, and nicotine has led to its use in detoxification treatments. In many instances, clients receive treatment in non-medical settings, with little by way of robust scientific clinical trials. This chapter provides an overview of the potential benefits that could arise from such research. This is balanced against the serious adverse effects that can occur due to undiagnosed health conditions and/or concomitant use of other drugs. A detailed update is provided of the 33 deaths known to have occurred, including 5 in the UK. Looking forward, there is a need to develop better opiate detoxification treatment against a background of increasing opioid-related fatalities. A congener of ibogaine, 18-MC, appears to be safer and is to undergo clinical trials. In the meantime, would-be consumers and treatment providers must make more careful, detailed risk-assessments before using ibogaine. Treatment outcomes, including deaths, need to be accurately recorded and published.
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Affiliation(s)
- John Martin Corkery
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, University of Hertfordshire, Hatfield, Hertfordshire, United Kingdom.
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Rubi L, Eckert D, Boehm S, Hilber K, Koenig X. Anti-addiction Drug Ibogaine Prolongs the Action Potential in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Cardiovasc Toxicol 2017; 17:215-218. [PMID: 27020671 PMCID: PMC5334404 DOI: 10.1007/s12012-016-9366-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Ibogaine is a plant alkaloid used as anti-addiction drug in dozens of alternative medicine clinics worldwide. Recently, alarming reports of life-threatening cardiac arrhythmias and cases of sudden death associated with the ingestion of ibogaine have accumulated. Using whole-cell patch clamp recordings, we assessed the effects of ibogaine and its main metabolite noribogaine on action potentials in human ventricular-like cardiomyocytes derived from induced pluripotent stem cells. Therapeutic concentrations of ibogaine and its long-lived active metabolite noribogaine significantly retarded action potential repolarization in human cardiomyocytes. These findings represent the first experimental proof that ibogaine application entails a cardiac arrhythmia risk for humans. In addition, they explain the clinically observed delayed incidence of cardiac adverse events several days after ibogaine intake. We conclude that therapeutic concentrations of ibogaine retard action potential repolarization in the human heart. This may give rise to a prolongation of the QT interval in the electrocardiogram and cardiac arrhythmias.
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Affiliation(s)
- Lena Rubi
- Department of Neurophysiology and - Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090, Vienna, Austria
| | - Daniel Eckert
- Department of Neurophysiology and - Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090, Vienna, Austria
| | - Stefan Boehm
- Department of Neurophysiology and - Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090, Vienna, Austria
| | - Karlheinz Hilber
- Department of Neurophysiology and - Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090, Vienna, Austria.
| | - Xaver Koenig
- Department of Neurophysiology and - Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090, Vienna, Austria
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Lavaud C, Massiot G. The Iboga Alkaloids. PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS 2017; 105:89-136. [PMID: 28194562 DOI: 10.1007/978-3-319-49712-9_2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Iboga alkaloids are a particular class of indolomonoterpenes most often characterized by an isoquinuclidine nucleus. Their first occurrence was detected in the roots of Tabernanthe iboga, a sacred plant to the people of Gabon, which made it cult object. Ibogaine is the main representative of this class of alkaloids and its psychoactive properties are well documented. It has been proposed as a drug cessation treatment and has a wide range of activities in targeting opioids, cocaine, and alcohol. The purpose of this chapter is to provide a background on this molecule and related compounds and to update knowledge on the most recent advances made. Difficulties linked to the status of ibogaine as a drug in several countries have hampered its development, but 18-methoxycoronaridine is currently under evaluation for the same purposes and for the treatment of leishmaniasis. The chapter is divided into six parts: an introduction aiming at defining what is called an iboga alkaloid, and this is followed by current knowledge on their biosynthesis, which unfortunately remains a "black box" as far as the key construction step is concerned. Many of these alkaloids are still being discovered and the third and fourth parts of the chapter discuss the analytical tools in use for this purpose and give lists of new monomeric and dimeric alkaloids belonging to this class. When necessary, the structures are discussed especially with regard to absolute configuration determinations, which remain a point of weakness in their assignments. Part V gives an account of progress made in the synthesis, partial and total, which the authors believe is key to providing solid solutions to the industrial development of the most promising molecules. The last part of the chapter is devoted to the biological properties of iboga alkaloids, with particular emphasis on ibogaine and 18-methoxycoronaridine.
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Affiliation(s)
- Catherine Lavaud
- Faculty of Pharmacy, Université de Reims Champagne-Ardenne, Institut de Chimie Moléculaire de Reims, UMR CNRS 7312, Case postale 44, UFR des Sciences Exactes et Naturelles, BP 1039, 51687, Reims, Cedex 2, France.
| | - Georges Massiot
- Université de Reims Champagne-Ardenne, Institut de Chimie Moléculaire de Reims, UMR CNRS 7312, Case postale 44, UFR des Sciences Exactes et Naturelles, BP 1039, 51687, Reims, Cedex 2, France
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Graziano S, Orsolini L, Rotolo MC, Tittarelli R, Schifano F, Pichini S. Herbal Highs: Review on Psychoactive Effects and Neuropharmacology. Curr Neuropharmacol 2017; 15:750-761. [PMID: 27799032 PMCID: PMC5771051 DOI: 10.2174/1570159x14666161031144427] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 06/12/2016] [Accepted: 03/10/2016] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND A new trend among users of new psychoactive substances' the consumption of "herbal highs": plant parts containing psychoactive substances. Most of the substances extracted from herbs, in old centuries were at the centre of religious ceremonies of ancient civilizations. Currently, these herbal products are mainly sold by internet web sites and easily obtained since some of them have no legal restriction. OBJECTIVE We reviewed psychoactive effects and neuropharmacology of the most used "herbal highs" with characterized active principles, with studies reporting mechanisms of action, pharmacological and subjective effects, eventual secondary effects including intoxications and/or fatalities Method: The PubMed database was searched using the following key.words: herbal highs, Argyreia nervosa, Ipomoea violacea and Rivea corymbosa; Catha edulis; Datura stramonium; Piper methysticum; Mitragyna speciosa. RESULTS Psychoactive plants here reviewed have been known and used from ancient times, even if for some of them limited information still exist regarding subjective and neuropharmacological effects and consequent eventual toxicity when plants are used alone or in combination with "classical" drugs of abuse. CONCLUSION Some "herbal highs" should be classified as harmful drugs since chronic administration has been linked with addiction and cognitive impairment; for some others taking into consideration only the recent trends of abuse, studies investigating these aspects are lacking.
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Affiliation(s)
- Silvia Graziano
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Laura Orsolini
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, College Lane Campus, University of Hertfordshire, Hatfield, Herts, AL10 9AB, UK
- Villa San Giuseppe Hospital, Hermanas Hospitalarias, Ascoli Piceno, Italy
- Polyedra Research, Polyedra, Teramo, Italy
| | - Maria Concetta Rotolo
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Roberta Tittarelli
- Unit of Forensic Toxicology (UoFT), Department of Anatomical, Histological, Forensic and Orthopedic Sciences, Sapienza University of Rome, Rome, Italy
| | - Fabrizio Schifano
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, College Lane Campus, University of Hertfordshire, Hatfield, Herts, AL10 9AB, UK
| | - Simona Pichini
- Department of Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
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Schep LJ, Slaughter RJ, Galea S, Newcombe D. Ibogaine for treating drug dependence. What is a safe dose? Drug Alcohol Depend 2016; 166:1-5. [PMID: 27426011 DOI: 10.1016/j.drugalcdep.2016.07.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 07/04/2016] [Accepted: 07/04/2016] [Indexed: 11/30/2022]
Abstract
The indole alkaloid ibogaine, present in the root bark of the West African rain forest shrub Tabernanthe iboga, has been adopted in the West as a treatment for drug dependence. Treatment of patients requires large doses of the alkaloid to cause hallucinations, an alleged integral part of the patient's treatment regime. However, case reports and case series continue to describe evidences of ataxia, gastrointestinal distress, ventricular arrhythmias and sudden and unexplained deaths of patients undergoing treatment for drug dependence. High doses of ibogaine act on several classes of neurological receptors and transporters to achieve pharmacological responses associated with drug aversion; limited toxicology research suggests that intraperitoneal doses used to successfully treat rodents, for example, have also been shown to cause neuronal injury (purkinje cells) in the rat cerebellum. Limited research suggests lethality in rodents by the oral route can be achieved at approximately 263mg/kg body weight. To consider an appropriate and safe initial dose for humans, necessary safety factors need to be applied to the animal data; these would include factors such as intra- and inter-species variability and for susceptible people in a population (such as drug users). A calculated initial dose to treat patients could be approximated at 0.87mg/kg body weight, substantially lower than those presently being administered to treat drug users. Morbidities and mortalities will continue to occur unless practitioners reconsider doses being administered to their susceptible patients.
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Affiliation(s)
- L J Schep
- National Poisons Centre, Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand.
| | - R J Slaughter
- National Poisons Centre, Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand
| | - S Galea
- Community Alcohol and Drug Services, Waitemata DHB, New Zealand; Social and Community Health and Centre for Addiction Research, University of Auckland, New Zealand
| | - D Newcombe
- Social and Community Health and Centre for Addiction Research, University of Auckland, New Zealand
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Kyzar EJ, Kalueff AV. Exploring Hallucinogen Pharmacology and Psychedelic Medicine with Zebrafish Models. Zebrafish 2016; 13:379-90. [PMID: 27002655 DOI: 10.1089/zeb.2016.1251] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
After decades of sociopolitical obstacles, the field of psychiatry is experiencing a revived interest in the use of hallucinogenic agents to treat brain disorders. Along with the use of ketamine for depression, recent pilot studies have highlighted the efficacy of classic serotonergic hallucinogens, such as lysergic acid diethylamide and psilocybin, in treating addiction, post-traumatic stress disorder, and anxiety. However, many basic pharmacological and toxicological questions remain unanswered with regard to these compounds. In this study, we discuss psychedelic medicine as well as the behavioral and toxicological effects of hallucinogenic drugs in zebrafish. We emphasize this aquatic organism as a model ideally suited to assess both the potential toxic and therapeutic effects of major known classes of hallucinogenic compounds. In addition, novel drugs with hallucinogenic properties can be efficiently screened using zebrafish models. Well-designed preclinical studies utilizing zebrafish can contribute to the reemerging treatment paradigm of psychedelic medicine, leading to new avenues of clinical exploration for psychiatric disorders.
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Affiliation(s)
- Evan J Kyzar
- 1 Department of Psychiatry, College of Medicine, University of Illinois at Chicago , Chicago, Illinois
| | - Allan V Kalueff
- 2 Research Institute for Marine Drugs and Nutrition, College of Food Science and Technology, Guangdong Ocean University (GDOU) , Zhanjiang, China .,3 ZENEREI Institute , Slidell, Louisiana.,4 Institute of Translational Biomedicine, St. Petersburg State University , St. Petersburg, Russia .,5 Institutes of Chemical Technology and Natural Sciences, Ural Federal University , Ekaterinburg, Russia .,6 The International Zebrafish Neuroscience Research Consortium (ZNRC) , Slidell, Louisiana
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Hildyard C, Macklin P, Prendergast B, Bashir Y. A Case of QT Prolongation and Torsades de Pointes Caused by Ibogaine Toxicity. J Emerg Med 2016; 50:e83-7. [DOI: 10.1016/j.jemermed.2015.06.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 06/15/2015] [Accepted: 06/23/2015] [Indexed: 11/16/2022]
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Koenig X, Hilber K. The anti-addiction drug ibogaine and the heart: a delicate relation. Molecules 2015; 20:2208-28. [PMID: 25642835 PMCID: PMC4382526 DOI: 10.3390/molecules20022208] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 11/11/2014] [Accepted: 11/26/2014] [Indexed: 12/13/2022] Open
Abstract
The plant indole alkaloid ibogaine has shown promising anti-addictive properties in animal studies. Ibogaine is also anti-addictive in humans as the drug alleviates drug craving and impedes relapse of drug use. Although not licensed as therapeutic drug and despite safety concerns, ibogaine is currently used as an anti-addiction medication in alternative medicine in dozens of clinics worldwide. In recent years, alarming reports of life-threatening complications and sudden death cases, temporally associated with the administration of ibogaine, have been accumulating. These adverse reactions were hypothesised to be associated with ibogaine’s propensity to induce cardiac arrhythmias. The aim of this review is to recapitulate the current knowledge about ibogaine’s effects on the heart and the cardiovascular system, and to assess the cardiac risks associated with the use of this drug in anti- addiction therapy. The actions of 18-methoxycoronaridine (18-MC), a less toxic ibogaine congener with anti-addictive properties, are also considered.
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Affiliation(s)
- Xaver Koenig
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, Vienna 1090, Austria.
| | - Karlheinz Hilber
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, Vienna 1090, Austria.
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Thurner P, Stary-Weinzinger A, Gafar H, Gawali VS, Kudlacek O, Zezula J, Hilber K, Boehm S, Sandtner W, Koenig X. Mechanism of hERG channel block by the psychoactive indole alkaloid ibogaine. J Pharmacol Exp Ther 2013; 348:346-58. [PMID: 24307198 DOI: 10.1124/jpet.113.209643] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ibogaine is a psychoactive indole alkaloid. Its use as an antiaddictive agent has been accompanied by QT prolongation and cardiac arrhythmias, which are most likely caused by human ether a go-go-related gene (hERG) potassium channel inhibition. Therefore, we studied in detail the interaction of ibogaine with hERG channels heterologously expressed in mammalian kidney tsA-201 cells. Currents through hERG channels were blocked regardless of whether ibogaine was applied via the extracellular or intracellular solution. The extent of inhibition was determined by the relative pH values. Block occurred during activation of the channels and was not observed for resting channels. With increasing depolarizations, ibogaine block grew and developed faster. Steady-state activation and inactivation of the channel were shifted to more negative potentials. Deactivation was slowed, whereas inactivation was accelerated. Mutations in the binding site reported for other hERG channel blockers (Y652A and F656A) reduced the potency of ibogaine, whereas an inactivation-deficient double mutant (G628C/S631C) was as sensitive as wild-type channels. Molecular drug docking indicated binding within the inner cavity of the channel independently of the protonation of ibogaine. Experimental current traces were fit to a kinetic model of hERG channel gating, revealing preferential binding of ibogaine to the open and inactivated state. Taken together, these findings show that ibogaine blocks hERG channels from the cytosolic side either in its charged form alone or in company with its uncharged form and alters the currents by changing the relative contribution of channel states over time.
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Affiliation(s)
- Patrick Thurner
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria (H.G., V.S.G., K.H., S.B., X.K.), Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria (P.T., O.K., J.Z., W.S.), Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (A.S.-W.)
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