COMPARISON OF A PLACEBO, N-DIMETHYLTRYPTAMINE, AND 6-HYDROXY-N-DIMETHYLTRYPTAMINE IN MAN

Psychedelic drug abuse potential assessment research for new drug applications and Controlled Substances Act scheduling

New medicines containing classic hallucinogenic and entactogenic psychedelic substance are under development for various psychiatric and neurological disorders. Many of these, including psilocybin, lysergic acid diethylamide (LSD), and 3,4-methylenedioxymethamphetamine (MDMA) are Schedule I controlled substances of the United States Controlled Substances Act (US CSA), and similarly controlled globally. The implications of the CSA for research and medicines development, the path to approval of medicines, and their subsequent removal from Schedule I in the US are discussed. This entire process occurs within the framework of the CSA in the US and its counterparts internationally in accordance with international drug control treaties. Abuse potential related research in the US informs the eight factors of the CSA which provide the basis for rescheduling actions that must occur upon approval of a drug that contains a Schedule I substance. Abuse-related research also informs drug product labeling and the risk evaluation and mitigation strategies (REMS) will likely be required for approved medicines. Human abuse potential studies typically employed in CNS drug development may be problematic for substances with strong hallucinogenic effects such as psilocybin, and alternative strategies are discussed. Implications for research, medicinal development, and controlled substance scheduling are presented in the context of the US CSA and FDA requirements with implications for global regulation. We also discuss how abuse-related research can contribute to understanding mechanisms of action and therapeutic effects as well as the totality of the effects of the drugs on the brain, behavior, mood, and the constructs of spirituality and consciousness.

Ayahuasca: Psychological and Physiologic Effects, Pharmacology and Potential Uses in Addiction and Mental Illness

Background:

Ayahuasca, a traditional Amazonian decoction with psychoactive properties, is made from bark of the Banisteriopsis caapi vine (containing beta-carboline alkaloids) and leaves of the Psychotria viridis bush (supplying the hallucinogen N,N-dimethyltryptamine, DMT). Originally used by indigenous shamans for the purposes of spirit communi-cation, magical experiences, healing, and religious rituals across several South American countries, ayahuasca has been in-corporated into folk medicine and spiritual healing, and several Brazilian churches use it routinely to foster a spiritual experi-ence. More recently, it is being used in Europe and North America, not only for religious or healing reasons, but also for rec-reation.

Objective:

To review ayahuasca’s behavioral effects, possible adverse effects, proposed mechanisms of action and potential clinical uses in mental illness.

Method:

We searched Medline, in English, using the terms ayahuasca, dimethyltryptamine, Banisteriopsis caapi, and Psy-chotria viridis and reviewed the relevant publications.

Results:

The following aspects of ayahuasca are summarized: Political and legal factors; acute and chronic psychological ef-fects; electrophysiological studies and imaging; physiological effects; safety and adverse effects; pharmacology; potential psychiatric uses.

Conclusion:

Many years of shamanic wisdom have indicated potential therapeutic uses for ayahuasca, and several present day studies suggest that it may be useful for treating various psychiatric disorders and addictions. The side effect profile ap-pears to be relatively mild, but more detailed studies need to be done. Several prominent researchers believe that government regulations with regard to ayahuasca should be relaxed so that it could be provided more readily to recognized, credible re-searchers to conduct comprehensive clinical trials.

Teratogenic effects of Mimosa tenuiflora in a rat model and possible role of N-methyl- and N,N-dimethyltryptamine

Mimosa tenuiflora is a shrub/tree found in northeastern Brazil sometimes eaten by livestock and believed to be responsible for malformations observed in many animals from that region. The teratogenic compounds in M. tenuiflora are not known. This study used pregnant rats fed M. tenuiflora and components therefrom for bioassay and fractionation of possible teratogenic compounds. Rat pups were examined for cranial-facial defects and skeletal malformations. Experimental diets included M. tenuiflora leaf and seed material, extracts of leaf and seed, alkaloid extracts of leaf and seed, and N-methyltryptamine and N,N-dimethyltryptamine. Pups from mothers who received M. tenuiflora plant material, methanol extracts, alkaloid extracts, and purified N-methyltryptamines had a higher incidence of soft tissue cleft palate and skeletal malformations. Results are summarized as to the frequency of observed cleft palate and other noted malformations for each diet versus control.

Pharmacology of ayahuasca administered in two repeated doses

RATIONALE

Ayahuasca is an Amazonian tea containing the natural psychedelic 5-HT(2A/2C/1A) agonist N,N-dimethyltryptamine (DMT). It is used in ceremonial contexts for its visionary properties. The human pharmacology of ayahuasca has been well characterized following its administration in single doses.

OBJECTIVES

To evaluate the human pharmacology of ayahuasca in repeated doses and assess the potential occurrence of acute tolerance or sensitization.

METHODS

In a double-blind, crossover, placebo-controlled clinical trial, nine experienced psychedelic drug users received PO the two following treatment combinations at least 1 week apart: (a) a lactose placebo and then, 4 h later, an ayahuasca dose; and (b) two ayahuasca doses 4 h apart. All ayahuasca doses were freeze-dried Amazonian-sourced tea encapsulated to a standardized 0.75 mg DMT/kg bodyweight. Subjective, neurophysiological, cardiovascular, autonomic, neuroendocrine, and cell immunity measures were obtained before and at regular time intervals until 12 h after first dose administration.

RESULTS

DMT plasma concentrations, scores in subjective and neurophysiological variables, and serum prolactin and cortisol were significantly higher after two consecutive doses. When effects were standardized by plasma DMT concentrations, no differences were observed for subjective, neurophysiological, autonomic, or immunological effects. However, we observed a trend to reduced systolic blood pressure and heart rate, and a significant decrease for growth hormone (GH) after the second ayahuasca dose.

CONCLUSIONS

Whereas there was no clear-cut tolerance or sensitization in the psychological sphere or most physiological variables, a trend to lower cardiovascular activation was observed, together with significant tolerance to GH secretion.

Autonomic, neuroendocrine, and immunological effects of ayahuasca: a comparative study with d-amphetamine

Ayahuasca is an Amazonian psychotropic plant tea combining the 5-HT2A agonist N,N-dimethyltryptamine (DMT) and monoamine oxidase-inhibiting β-carboline alkaloids that render DMT orally active. The tea, obtained from Banisteriopsis caapi and Psychotria viridis, has traditionally been used for religious, ritual, and medicinal purposes by the indigenous peoples of the region. More recently, the syncretistic religious use of ayahuasca has expanded to the United States and Europe. Here we conducted a double-blind randomized crossover clinical trial to investigate the physiological impact of ayahuasca in terms of autonomic, neuroendocrine, and immunomodulatory effects. An oral dose of encapsulated freeze-dried ayahuasca (1.0 mg DMT/kg body weight) was compared versus a placebo and versus a positive control (20 mg d-amphetamine) in a group of 10 healthy volunteers. Ayahuasca led to measurable DMT plasma levels and distinct subjective and neurophysiological effects that were absent after amphetamine. Both drugs increased pupillary diameter, with ayahuasca showing milder effects. Prolactin levels were significantly increased by ayahuasca but not by amphetamine, and cortisol was increased by both, with ayahuasca leading to the higher peak values. Ayahuasca and amphetamine induced similar time-dependent modifications in lymphocyte subpopulations. Percent CD4 and CD3 were decreased, whereas natural killer cells were increased. Maximum changes occurred around 2 hours, returning to baseline levels at 24 hours. In conclusion, ayahuasca displayed moderate sympathomimetic effects, significant neuroendocrine stimulation, and a time-dependent modulatory effect on cell-mediated immunity. Future studies on the health impact of long-term ayahuasca consumption should consider the assessment of immunological status in regular users.

Effect of ring fluorination on the pharmacology of hallucinogenic tryptamines

A series of fluorinated analogues of the hallucinogenic tryptamines N,N-diethyltryptamine (DET), 4-hydroxy-N,N-dimethyltryptamine (4-OH-DMT, psilocin), and 5-methoxy-DMT was synthesized to investigate possible explanations for the inactivity of 6-fluoro-DET as a hallucinogen and to determine the effects of fluorination on the molecular recognition and activation of these compounds at serotonin receptor subtypes. The target compounds were evaluated using in vivo behavioral assays for hallucinogen-like and 5-HT(1A) agonist activity and in vitro radioligand competition assays for their affinity at 5-HT(2A), 5-HT(2C), and 5-HT(1A) receptor sites. Functional activity at the 5-HT(2A) receptor was determined for all compounds. In addition, for some compounds functional activity was determined at the 5-HT(1A) receptor. Hallucinogen-like activity, evaluated in the two-lever drug discrimination paradigm using LSD-trained rats, was attenuated or abolished for all of the fluorinated analogues. One of the tryptamines, 4-fluoro-5-methoxy-DMT (6), displayed high 5-HT(1A) agonist activity, with potency greater than that of the 5-HT(1A) agonist 8-OH-DPAT. The ED(50) of 6 in the two-lever drug discrimination paradigm using rats trained to discriminate the 5-HT(1A) agonist LY293284 was 0.17 micromol/kg, and the K(i) at [(3)H]8-OH-DPAT-labeled 5-HT(1A) receptors was 0.23 nM. The results indicate that fluorination of hallucinogenic tryptamines generally has little effect on 5-HT(2A/2C) receptor affinity or intrinsic activity. Affinity at the 5-HT(1A) receptor was reduced, however, in all but one example, and all of the compounds tested were full agonists but with reduced functional potency at this serotonin receptor subtype. The one notable exception was 4-fluoro-5-methoxy-DMT (6), which had markedly enhanced 5-HT(1A) receptor affinity and functional potency. Although it is generally considered that hallucinogenic activity results from 5-HT(2A) receptor activation, the present results suggest a possible role for involvement of the 5-HT(1A) receptor with tryptamines.

A new metabolic pathway for N,N-dimethyltryptamine

N,N-Dimethyltryptamine (DMT) undergoes a major structural alteration when added to whole human blood or its red blood cells in vitro. A new high-pressure liquid chromatography (HPLC) peak is present in extracts of these treated tissues. The compound responsible for this peak has been identified by ultraviolet spectrophotometry and by mass spectrometry as dimethylkynuramine (DMK). The enzyme responsible for this appears to be different from tryptophan 2,3-dioxygenase and also from indoleamine 2,3-dioxygenase.

Indolealkylamine and phenalkylamine hallucinogens: a brief overview

Various indolealkylamine and phenalkylamine derivatives are hallucinogenic in man and/or are behaviorally active in animals. This overview is divided into two parts. The first part attempts to bring together information concerning the activity of indolealkylamines (i.e., tryptamines, alpha-methyltryptamines, N,N-dimethyltryptamines, N-alkyltryptamines, lysergic acid derivatives and beta-carbolines) and phenalkylamines (i.e., phenethylamines, phenylisopropylamines) along with major key references, and with emphasis on those agents not recently reviewed. The latter portion of this overview describes some of the work being conducted in our laboratories in an effort to elucidate the role of the neurotransmitter serotonin in the mechanism of action of various indolealkylamine and phenalkylamine hallucinogens.

Behavioral effects and metabolic fate of N,N-dimethyltryptamine in mice pretreated with beta-diethylaminoethyl-diphenylpropylacetate (SKF 525-A), improniazid and chlorpromazine

Behavioral aspects and metabolic fate of N,N-dimethyltryptamine (DMT) were studied in mice pretreated with beta-diethylaminoethyl-diphenylpropylacetate (SKF 525-A), iproniazid or chlorpromazine (CPZ). DMT at doses of 2.5, 10.0, and 25.0 mg/kg produced several behavioral changes in a dose-related manner: inhibition of spontaneous locomotor movement, enhanced fright responses to sound stimuli, trembling, head twitching, inco-ordinated movements of hind-legs, flat or extended tail and abnormal posture with the extension of hind-legs. Pretreatment with ipromazid (153 mg/kg; 4 hr) but not SKF 525-A (50 mg/kg; 1 hr) prolonged the behavioral effects produced by 2.5 mg/kg DMT while CPZ (15 mg/kg; 0.5 hr) completely abolished the responses induced by 25 mg/kg DMT. Earlier behavioral effects generally coincided with the brain concentrations of DMT. Dose-dependent increases with rapid uptake and disappearance in the brain, plasma and hepatic levels of DMT were measured with doses of 10 and 25 mg/kg DMT. Iproniazid but not SKF 525-A markedly enhanced tissue levels of DMT. it is concluded that DMT is metabolized chiefly by monoamine oxidase rather than by drug-metabolizing hepatic microsomal enzymes and that DMT-induced behavioral effects are due to the parent compound rather than its metabolite.

Detection of psychotomimetic N,N-dimethylated indoleamines in the urine of four schizophrenic patients

Pollin, Cardon and Kety (18) investigated the effects of large doses of various amino acids in combination with a monoamine oxidase (MAO) inhibitor on the behaviour of schizophrenics. They found that methionine in the presence of such an inhibitor was capable of producing behavioural changes which may ‘represent a biochemically induced acute flare-up of a chronic schizophrenic process on the one hand, or a toxic delirium superimposed upon chronic schizophrenia on the other’. Brune and Himwich (8) confirmed the clinical results of Pollin et al. On the basis of their previous work indicating that tryptamine appeared in increased concentrations in the urine before and during the activation of psychotic symptoms, they suggested that under loading conditions the formation of various N,N-dimethylated indoleamines might be facilitated in the body. The tertiary indoleamines so formed might mediate the psychotic effect of methionine with a MAO inhibitor on schizophrenic patients.

6-hydroxylation: effect on the psychotropic potency of tryptamines

6-Hydroxy-5-methoxy-N,N dimethyltryptamine and 5-methoxy-N, N-dimnethyltryptamine were synthesized and their psychotropic effects compared on trained rats in a Skinner box. The nonhydroxylated form was the more po tent. The metabolism of 5-methoxytryp tophol acetate ester was also studied to determine whether hydroxylation might occur in other than the six position with exogenous indoles. One metabolite was formed, with properties of a hydroxy-5-methoxyindole-3-acetic acid, which proved on chromatography not to be the 6-hydroxy structural isomer. Phar macologic and metabolic studies suggest that psychotropic activity of trypt amines may result from metabolites other than the 6-hydroxylated forms.