Ibogaine : A review – Chapter 1

Kenneth R. Alper

The Alkaloids. Chemistry and Biology, 2001, 56,  38 pp

DOI: 10.1016/S0099-9598(01)56005-8

 

I. Introduction, Chemical Properties, and Historical Time Line …………………
A. Introduction………………………………………………………………………………………
B. Chemical Structure and Properties ……………………………………………………..
C. Historical Time Line ………………………………………………………………………….
II. Mechanisms of Action ……………………………………………………………………….
A. Neurotransmitter Activities…………………………………………………………………
B. Discrimination Studies……………………………………………………………………….
C. Effects on Neuropeptides…………………………………………………………………….
D. Possible Effects on Neuroadaptations Related to Drug Sensitization
or Tolerance ………………………………………………………………………………………….
III. Evidence of Efficacy in Animal Models………………………………………………..
A. Drug Self-Administration ……………………………………………………………………
B. Acute Opioid Withdrawal ……………………………………………………………………
C. Conditioned Place Preference………………………………………………………………
D. Locomotor Activity…………………………………………………………………………….
E. Dopamine Efflux…………………………………………………………………………………
IV Evidence of Efficacy and Subjective Effects in Humans …………………………
A. Evidence of Efficacy…………………………………………………………………………….
B. Subjective Effects ……………………………………………………………………………….
V. Pharmacokinetics ……………………………………………………………………………….
A. Absorption………………………………………………………………………………………….
B. Distribution ……………………………………………………………………………………….
C. Metabolism ……………………………………………………………………………………….
D. Excretion …………………………………………………………………………………………..
VI. Safety ……………………………………………………………………………………………….
A. Neurotoxicity …………………………………………………………………………………….
B. Cardiovascular Effects ………………………………………………………………………..
C. Fatalities…………………………………………………………………………………………….
D. Abuse Liability …………………………………………………………………………………..
VII. Learning, Memory, and Neurophysiology……………………………………………
A. Learning, Memory, and Addiction…………………………………………………………
B. Effects of Ibogaine on Learning and Memory ………………………………………..
C. Ibogaine and the EEG………………………………………………………………………….
D. Goutarel’s Hypothesis………………………………………………………………………….
VIII. Anthropological and Sociological Perspectives …………………………………..

IX. Economic and Political Perspectives……………………………………………………
A. Economic Incentives and the Development of Ibogaine…………………………..
B. Political Issues ……………………………………………………………………………………
X. Conclusions………………………………………………………………………………………..
References……………………………………………………………………………………………..

 

I. Introduction and Historical Time Line

A. Introduction
Ibogaine, a naturally occurring plant alkaloid with a history of use as a medicinal and ceremonial agent in West Central Africa, has been alleged to be effective in the treatment of drug abuse. The National Institute on Drug Abuse (NIDA) has given significant support to animal research, and the U.S. Food and Drug Administration (FDA) has approved Phase I studies in humans. Evidence for ibogaine’s effectiveness includes a substantial preclinical literature on reduced drug self-administration and withdrawal in animals, and case reports in humans. There is relatively little financial incentive for its development by the pharmaceutical industry because ibogaine is isolated from a botanical source in which it naturally occurs, and its chemical structure cannot be patented. This has left the academic community and the public sector with a crucial role in research on ibogaine, which was a major reason for organizing the First International Conference on Ibogaine.

A major focus of the Conference was the possible mechanism(s) of action of ibogaine. Ibogaine is of interest because it appears to have a novel mechanism of action distinct from other existing pharmaco-therapeutic approaches to addiction, and it potentially could provide a paradigm for understanding the neurobiology of addiction and the development of new treatments. Another important focus of the Conference was to review human experience with ibogaine and preclinical and clinical evidence of efficacy and safety. The Conference also featured presentations related to the sociological and anthropological aspects of the sacramental context of the use of iboga in Africa and the distinctive ibogaine subculture of the United States and Europe.

B. Chemical Structure and Properties
Ibogaine (10-methoxyibogamine) (Figure 1) is an indole alkaloid with molecular formula C20H26N20 and molecular weight 310.44. Ibogaine is the most abundant alkaloid in the root bark of the Apocynaceous shrub Tabernanthe iboga, which grows in West Central Africa. In the dried root bark, the part of the plant in which alkaloid content is highest, total alkaloid content is reportedly 5 to 6% (1).

Ibogaine has a melting point of 153°, a pKa of 8.1 in 80% methylcellosolve, and it crystallizes as prismatic needles from ethanol. Ibogaine is levorotatory [α]D –53° (in 95% ethanol), soluble in ethanol, ether, chloroform, acetone and benzene, but it is practically insoluble in water. Ibogaine is decomposed by the action of heat and light. Ibogaine hydrochloride decomposes at 299°, is also levorotatory [α]D –63° (ethanol), [α]D –49° (H2O), and is soluble in water, methanol, and ethanol, slightly soluble in acetone and chloroform, and practically insoluble in ether (2). The X-ray crystal analysis that confirmed the structure of ibogaine has been described (3). The literature provides references to the mass spectrum of ibogaine (4), and the proton (5,6) and the 13C (7-9) NMR spectra of ibogaine and other iboga alkaloids. Analytic chemical methods for extraction, derivatization, and detection of ibogaine utilizing combined gas chromatographymass spectometry have been described (10-13).

Ibogaine undergoes demethylation to form its principal metabolite, noribogaine, also known as O-desmethylibogaine or 10-hydroxyibogamine. 18- methoxycoronaridine (18-MC, see Glick et al. in this volume) is an ibogaine congener that appears to have efficacy similar to ibogaine in animal models of drug dependence with evidence of less potential toxicity.

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Ibogaine_a_review