69 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
THERAPEUTIC GUIDELINES: DANGERS
AND CONTRAINDICATIONS IN
THERAPEUTIC APPLICATIONS OF
E D E F R E C S K A
INT RODUC TIO N
There are widespread beliefs about the dangers of hallucinogenic drugs and fre-
quent media reports attributing fatalities to hallucinogens. This media bias was
typical in the early 1970s when much attention was focused on supposed chromo-
some damage and birth defects in children born to mothers who had taken LSD
(lysergic acid diethylamide) during pregnancy. Later on, negative results of
better-controlled, rigorous investigations (Muneer 1978) refuted the earlier
alarmist concerns, but these received very little attention in the media. The con-
troversial nature of the U.S. drug policy and its influence on government-spon-
sored research of illicit drugs has recently drawn media attention due to
investigational flaws of highly publicized research claiming harmful effects
Hallucinogens actually do have a long history of safe administration in legal,
controlled research settings (Strassman 1984), contrary to the preconceptions
influencing public and professional media. These preconceptions, even when
derived from unbiased publications, are related to illicit use (and abuse), rather
than responsible clinical use (e.g., see Griffiths et al. 2006). Unfortunately, a
hallucinogenic drug’s safety has been judged by its abuse and that has been
applied to making decisions regarding clinical use. The inconvenient truth is
that the opinion of most of the health care providers and legislation makers on
hallucinogenic agents is not well founded scientifically.
T H E R A P E U T I C GU I D E L I N E S 7 0
The purpose of this chapter is to review safety information available in the
literature on hallucinogen use, and sort out those data from the reported
complications of their abuse. The chapter summarizes these analyses in propos-
ing guidelines for clinical application of hallucinogens in anticipation of
supportive regulatory changes. Since there is currently no FDA (Food and Drug
Administration) approval for therapeutic use of any hallucinogen compound, the
therapeutic guidelines presented are tentative and preliminary.
To preview these findings, the various hallucinogenic compounds are physi-
cally safe, with the possible exception of the phenethylamine hallucinogens (such
as Ecstasy), which have the risk of causing cardiovascular emergencies and liver
failure. There are limited records establishing death from overdoses directly
attributable to their ingestion alone. The number of annual drug-related deaths in
the United States is as follows (based on latest reports from Centers for Disease
Control and Prevention)
Tobacco kills about 440,000.
Alcohol kills about 75,000.
Secondary smoke from tobacco kills about 50,000.
Cocaine kills about 3,400.
Heroin kills about 2,000.
Over-the-counter drugs kill about 2,000.
Marijuana and LSD kill 0.
All illegal drugs combined kill about 5,500 people per year in the United
States, or about
of the number killed by alcohol and tobacco. Tobacco kills
more people each year than all of the subjects killed by all of the illegal drugs in
the last century (NIDA Research Reports).
In contrast, the so-called
hallucinogens have virtually no fatalities (see below for more details on safety).
CLASSIFICATION, CHEMICAL STRUCTURE, AND MECHANISM OF ACTION
The conventional use of the term “hallucinogen” disproportionately
emphasizes perceptual effects, neglecting central actions on emotion and
cognition as well. Psychopharmacologists define as hallucinogenic any agent that
causes alterations in perception, cognition, and mood in the presence of an
otherwise clear sensorium (lucid awareness). Most commonly this classification
includes three major groups—indolealkylamines, ergolines, and phenethyl-
amines—and excludes other substances that may induce hallucinations with
profoundly altered orientation and vigilance. Excluded are the anticholinergic
agents (i.e., plants such as datura), the dissociative anesthetics such as PCP
(phencyclidine), and the psychostimulants such as amphetamine and cocaine.
71 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
The chemical structures of the classic hallucinogenic drugs are the basis for
their classification into three groups: 1) simple indolealkylamine hallucinogens
[e.g., DMT (N,N-dimethyltryptamine) and psilocybin], which have a common
indolealkylamine structure with the neurotransmitter (endogenous signal trans-
ferring compound) serotonin; 2) the ergolines, which share an indole group (e.g.,
LSD); and 3) the ring-substituted phenethylamine hallucinogens (e.g., mescaline
and Ecstasy). The indole alkaloid ibogaine is a complex indolealkylamine
compound, a beta-carboline derivative akin to harmaline and harmine. The latter
is an active, although not the hallucinogenic component of the ayahuasca brew
The indole structure found in serotonin is a common chemical characteristic
of these compounds and suggests a specific mechanism of hallucinogenic effect
exerted on the serotonergic system. Typical clinico-pharmacological features of
classical hallucinogens involve alterations of all cortical functions including
perception, mood, and cognition. They share common mechanisms in attaching to
serotonin receptors through molecules that bind to the neurotransmitters sites for
transferring the signal to the next neuron in the network. It is the activation of
the serotonin2A and serotonin2C receptors in the brain that primarily mediates
their psychedelic effects.
EPIDEMIOLOGY: PREVALENCE AND TRENDS OF HALLUCINOGEN USE
Hallucinogenic drugs are not commonly used in the Western world, although
their use is considered by NIDA to be abuse by definition. Data from the 2004
NSDUH (National Survey on Drug Use and Health) suggests that approximately
34.3 million Americans aged 12 and older reported trying hallucinogens at least
once during their lifetimes, representing 14.3% of the population. Approximately
3.9 million reported hallucinogen use during the past year, and 929,000 reported
“current” use of hallucinogens (past month). Ecstasy [MDMA (3,4-methylene-
dioxy-N-methylamphetamine)] and LSD are the most commonly used hallucino-
gens. Marijuana is the most commonly used illicit drug: according to the 2004
NSDUH, nearly half (about 40%) of Americans over the age of 12 have tried
marijuana at least once (Substance Abuse and Mental Health Services
The incidence of hallucinogen use has exhibited two notable periods of
increase. Between 1965 and 1969, there was a tenfold increase in the estimated
annual number of initiates. This increase was driven primarily by the use of
LSD. The second period of increase in first-time hallucinogen use occurred from
around 1992 until 2000, fueled mainly by increases in the use of Ecstasy
(MDMA). Lately, there is an overall drop in hallucinogen incidence from 1.6 mil-
lion to below 1 million, coinciding with decreases in initiation of both LSD and
Ecstasy (MDMA) as it was evident in data collected between 2001 and 2004
(Substance Abuse and Mental Health Services Administration 2005).
T H E R A P E U T I C GU I D E L I N E S 7 2
The yearly national surveys on drug abuse repeatedly indicate that substance
use, and in particular hallucinogen use, varies by race and ethnicity. Black youths
were less likely to have used any hallucinogen in their lifetime compared with
white, Asian, or Hispanic youths. White and Asian youths had similar rates of
hallucinogen use, except that whites were much more likely than Asians to have
used psilocybin at least once in their lifetime.
HALLUCINOGEN ACUTE TOXICITY
The traditional measure of acute drug toxicity is “therapeutic index”: a ratio of
the dose that kills 50% of subjects (LD50) to the dose that is effective in 50% of
subjects (ED50). According to the Registry of Toxic Effects, the “therapeutic
index” for indolealkylamines and ergolines is above 600 (higher numbers
indicate a better safety profile). For cannabis, the index is even higher: it is on
the order of 10,000s. Therefore, these agents are relatively nonlethal in comparison
to other substances. For example, the therapeutic index of aspirin is 199 and for
nicotine 21, with the phenethylamine psychostimulants (such as methampheta-
mine) falling into this range.
There is no known recorded death due to marijuana intoxication at any time in
U.S. history. There are no documented toxic fatalities from LSD use either.
There was a report (Klock et al. 1974) of accidental overdose of pure LSD that
was mistaken for cocaine and snorted by eight individuals in quantities estimated
at between 10,000 and 100,000 µg. In this case, the subjects experienced mental
status changes characterized by hallucinations and confusion, and suffered from
hemorrhage; the latter possibly mediated by LSD antagonism of platelet sero-
tonin function. All subjects have recovered. One ayahuasca-related death was
reported (Sklerov et al. 2005), an obscure case which needs further clarification
(Callaway et al. 2006). All over the world up to the year 2006, at least eight per-
sons have died after having taken ibogaine. One of them was a woman in the
United States, who had been previously treated with ibogaine 25 days earlier. In
her case, the cause of death was mesenteric arterial thrombosis related to cellulitis,
and a role for ibogaine in the fatal outcome was not assumed. Ecstasy (MDMA)
leads the group with an estimated annual fatality rate to be about three to four
deaths in one million users.
Fatal outcome of Ecstasy (MDMA) abuse is due to
hyperpyrexia (heatstroke), rhabdomyolysis (muscle breakdown), liver failure,
cardiac arrhythmias, strokes, coagulopathy, or drug-related accidents. These
fatalities depend on mechanisms that are not specific to Ecstasy (MDMA) but
common to all the amphetamines (Kalant 2001), and result from causes which
most of the time cannot be separated from alcohol consumption and excessive
physical exercise characteristic of rave dancing.
More casualties have been reported, when people abusing hallucinogens
used them in combination with other potentially more dangerous drugs and did
irresponsible things under their influence. When used in improper settings—
mostly outside medical or religious practices—hallucinogen intoxication can be
disturbing and on occasions may temporarily increase the risk of suicidal behavior.
After large doses of cocaine, amphetamines, LSD, and PCP, certain individuals
73 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
may experience violent outbursts, probably because of preexisting psycho-
pathology. Crimes or bizarre behavior associated with hallucinogen intoxication
are regularly reported by the media. Sensationalization and exaggeration cannot be
ruled out in the background, since many more morbidity and mortality cases
related to common substances like alcohol are happening every day and those
have been less highlighted in the media. Of all psychoactive substances, alcohol
is the only one whose consumption has been shown to commonly increase
Nonetheless, it is recognized that there is significant variability in the
response to hallucinogenic agents both interindividually (between individuals)
and intraindividually (in the same individual at different times). In part, this is
related to the set and setting (Faillace and Szara 1968). In subjects who are
unaware of the hallucinogen administration, the incidence of adverse effects is
much higher. Generally, uninformed subjects show more anxiety, and cognitive
disruption, in contrast to the others who have an excess of euphoric responses. A
second set of factors that influence hallucinogenic response are related to the per-
sonality of the subject. Acute psychedelic drug intoxication can manifest features
of paranoia, confusion, and agitated behavior in a time-limited manner. This was
one of the features supporting the proposition that psychedelic drugs were exper-
imentally useful in producing a clinically relevant, discrete episode of psychosis in
the “psychotomimetic” (psychosis mimicking) model. Psychosis is the term used
for denoting the distortion or disorganization of a person’s capacity to recognize
reality, think rationally, or communicate with others. The “psychotomimetic”
effects of hallucinogenic drugs (e.g., LSD, psilocybin, and mescaline) have been
suggested to resemble the symptoms of acute schizophrenia.
Originally, hallucinogens carried the misnomer of “psychotogenic” (psychosis
generating) agents, but the hallucinogenic effect is distinct from psychosis on
several accounts; essentially, the two experiences are fundamentally different.
Reality control is well maintained after minimal experience with hallucinogens,
and the psychedelic effect is actively sought by users. Psychosis is neither volun-
tary nor desired. It is a disordered mental state over which the subject has no con-
trol. Hallucinogenic agents, when taken in appropriate settings in a responsible
manner, induce a coherent mental state with feeling of increased internal order
and personal growth. An experienced hallucinogen user may be regarded as a
competent navigator or a “co-dancer” with the drug (Shanon 2002). No such
statement applies to a psychotic. Sporadic anecdotal observations noticed a rela-
tionship between the onset of schizophrenia and the hallucinogen use in a vulner-
able population. However, when schizophrenic symptoms did persist beyond 24
hours, it appeared that the particular syndrome was a hallucinogen-precipitated
event in schizophrenia-prone individuals (e.g., those with relatives with psychiatric
problems), rather than a specific and genuine hallucinogen-induced persistent
T H E R A P E U T I C GU I D E L I N E S 7 4
Recent reports (Caspi et al. 2005; Henquet et al. 2006) indicate that people
with a certain gene variant (Val allele) of the COMT (catecholamine-O-methyl-
transferase enzyme), an enzyme responsible for the synaptic elimination of
dopamine) are more vulnerable to a schizophrenia-like psychosis after cannabis
abuse, and regular use of cannabis is a risk factor of schizophrenia. Carriers of
the Val allele were most sensitive to cannabis-induced psychotic experiences,
but this was conditional on the presence of pre-existing psychosis liability. Canna-
bis abuse had no such adverse influence on individuals with two copies of the Met
allele. These findings underline the importance of thorough screening before
enrollment into a hallucinogen trial, and explain why such precaution is so helpful
for minimizing the risk of adverse outcomes.
HALLUCINOGENS AND PREGNANCY
It is a well-known fact that drug use in pregnant women can be associated
with a number of serious complications for mother and child. There are satisfac-
tory data on harmful effects of alcohol, tobacco, marijuana, and cocaine on preg-
nancy and neonatal outcome, which usually involves vasoconstriction of the
placental vessels resulting in placental abruption, spontaneous abortion, intra-
uterine growth retardation, preterm delivery, and stillbirth. However, only little
evidence is available about the effects of classical hallucinogens like LSD or
Ecstasy (MDMA) (von Mandach 2005). The dissociative anesthetic ketamine is an
exception: it has been shown to be safe to use in pregnant animals (i.e., no sig-
nificant adverse effects on the fetus).
Usually, when facing a decision regarding the use of a medication in preg-
nancy, the therapist has to weigh the risks of using the drug against the risks of
not using it (i.e., the effects of the untreated illness itself on pregnancy). The lack
of information means that strict precautions have to be maintained, and the thera-
pist must look for alternative treatments. Even in cases of the most positive thera-
peutic outcome of the ongoing clinical trials with hallucinogens, their use in
pregnant women cannot expect anykind of liberalization in the foreseeable future.
ACUTE CLINICAL EFFECTS
Common psychedelic experiences include a profound change of perception
which can include visual, auditory, olfactory (smell related), gustatory (taste
related) and somatic (bodily) illusions or hallucinations, and synesthesias. The
latter are unusual blending of sensory modalities, for example, sounds may be
perceived as images, or colors may be perceived as smells. At the onset of hallu-
cinogen action, there may be a feeling of energy in the body, and the sense that
things are different than usual. As the effects intensify, a wide variety of profound
mental changes may occur. The full blown psychedelic experience is usually
accompanied by intensified mood, or exaggeration of the emotional state existing
at the time of ingestion of the drug. This can include euphoria or elation, depres-
sion, anxiety, and panic feelings. Increased visual imagery with closed eyes is the
most common perceptual change. Open-eye visual hallucinations are more likely
75 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
to occur at higher doses, and may affect the behavior of inexperienced or unat-
tended subjects. High-dose effects may also include extreme time-dilation, with
seconds or minutes feeling like hours or days. Cognition can be altered to the
extent that the experience takes on a mystical quality, and past memories may be
re-experienced with picture-like intensity. Advanced users may experience
expanded spiritual awareness or a sense of universal understanding through their
use of hallucinogens, and report religious revelations, spiritual awakening, disso-
lution of the ego, near-death experiences, and encounters with seemingly autono-
mous entities. While these experiences are described by many people as pleasant
(good trips), and serve basis for hallucinogen abuse, to some they may be confus-
ing and frightening (bad trips).
ACUTE SIDE EFFECTS
When used in moderate psychedelic doses, hallucinogens may cause
common adverse reactions (harmless with minimal care) such as nausea, vomit-
ing, dizziness, headaches, insignificant elevation in pulse and blood pressure,
dilated pupils, slightly elevated temperature, raising of skin-hair, impaired co-
ordination, and increased reflexes. These symptoms usually begin within one
hour after taking the drug and can last up to several hours (depending on the rate
of absorption and metabolism of the drug). Various blood hormones and liver
enzymes can also show clinically insignificant, temporary elevation.
EMERGENCY CARE OF HALLUCINOGEN-INDUCED ADVERSE EFFECTS
This chapter is about the risks of hallucinogenic agents used in a clinical,
well-controlled, secure setting. After proper and thorough screening of enrolled
subjects, fewer complications are expected than from uncontrolled street abuse.
Nevertheless, the hospital environment provides less than ideal atmosphere for
the psychedelic experience (Strassman 2000). Symptoms of acute hallucinogen
drug intoxication may develop, which can manifest in paranoia, confusion, fear of
death, and disordered self-control.
The focus of care is to prevent subjects from harming themselves or others
and reduce complications related to acute effects until these time-limited
phenomena resolve. The toxic psychosis generally resolves in two to six hours.
At times after effects, such as mild depersonalization–derealization (uneasy feeling
of changed personality and reality), may linger for a couple of days. Calm,
reassuring, and nonthreatening behavior can be useful in “talking down” patients
to allow necessary treatment to be applied and interventions to proceed. Subjects
need to be reassured that they are not “crazy,” what they sense is “just” the result
of a chemical, and will go away soon without a trace, with the eventual return of
ordinary reality. The optimal placement of sufferers is under one-to-one supervi-
sion (one trained staff person attending the patient), in a quiet room with
diminished lighting and other stimuli. Both stimulus deprivation and overstimu-
lation have to be avoided. Bed rest in supine position is not necessary, and is dis-
advantageous in patients with nausea and vomiting.
T H E R A P E U T I C GU I D E L I N E S 7 6
Appropriate use of chemical or physical restraints may be required if verbal
reassurance is not working. Physical restraints are seldom needed, and must be the
last resort. Benzodiazepines are probably the safest sedatives and can be
effective for calming most subjects. For fast response, these agents are best
administered intravenously. More severe reactions of anxiety or dangerous levels
of agitation may require antipsychotic medication. First-generation antipsy-
chotics (such as haloperidol or droperidol) must be avoided because of narrow
receptor profile (lack of serotonin blockade) and cardiac side effects. Second-
generation antipsychotics with serotonin2A antagonism and parenteral formu-
lation are safer and more effective.
The therapeutic approaches of modern medicine can be combined with some
nonintrusive traditional techniques: reciting mantras and gentle, simultaneous
massaging of the eyebrow region (6th chakra) and the navel region (3rd chakra).
While hallucinogenic agents are classified as drugs causing dependence, they
are physiologically nonaddictive. There is no evidence that these drugs produce
physical withdrawal symptoms when its chronic use is stopped (American Psy-
chiatric Association 1994). On the other hand, the tolerance phenomenon is well-
known. Psilocybin, LSD, and mescaline users quickly develop a high degree of
tolerance for the drug effect: after repeated use, they need increasingly larger
doses to produce similar responses. Cross-tolerance is built up for other
serotonergic hallucinogenic drugs, such as psilocybin and mescaline, but not for
drugs such as marijuana, amphetamines, and PCP, which do not act directly on the
serotonin receptors. LSD given daily becomes less effective at the same dose
(Isbell et al. 1956). This tolerance is short-lived, lasting only for several days; in
humans, tolerance to gross behavioral changes develops in four to seven days of
daily administration and lasts approximately three days. Schizophrenic patients
may develop tolerance sooner, in two to three days (for review, see Abraham et al.
1996). DMT is unique in this respect: this given frequently does not elicit
tolerance neither in animal (Kovacic and Domino 1976) nor in human
(Strassman et al. 1996) experiments. Although DMT acts on the same receptors as
LSD, its cross-tolerance with LSD and other serotonergic hallucinogens is limited.
LONG -TERM EFFECTS
The widely publicized “flashbacks” associated with the hallucinogenic drugs
attest to their long-term effects. A number of chronic clinical syndromes due to
hallucinogenic drugs have been recognized, including hallucinogen-induced
persistent psychosis and hallucinogen persisting perception disorder (formerly
post-hallucinogen perception disorder).
77 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
HALLUCINOGEN-INDUCED PERSISTENT PSYCHOSIS
The overwhelming nature of a full-blown psychedelic experience can lead to
significant psychological disturbances after the acute drug effects have worn off.
Under some hallucinogens, especially LSD, users may experience devastating
mental effects that persist longer than one month after the trip has ended. These
long-lasting psychosis-like effects of the drug are labeled as a “hallucinogen-
induced persistent psychosis,” and distinguished from the “hallucinogen persist-
ing perception disorder” described subsequently. Hallucinogen-induced
persistent psychosis commonly includes a dramatic affective component with
mood swings from mania to profound depression, religious thought contents,
vivid visual disturbances, and hallucinations not typical in schizophrenia (i.e.,
not auditory hallucinations of conversing, commenting, or commanding voices).
The clinical picture of the hallucinogen-induced persistent psychosis appears to
resemble schizoaffective disorders (schizophrenia-like disorder with prominent
mood swings) with the not-infrequent addition of visual disturbances. It was
noted in an early LSD experiment (Fink et al. 1966, p. 453) with persistent psy-
chotic patients that, “the hazard of LSD administration appears not to be in the
precipitation of a schizophrenic-like state but rather in decreasing emotional and
affective controls and inducing a persistent state of altered consciousness.”
This type of adverse hallucinogen drug effect may also be akin to the patho-
logical sequelae of psychological traumas such as rape, natural disaster, or combat
experience. These effects may last for years and can affect people who have no
history or other symptoms of psychiatric disorder. Nevertheless, investigators have
found early on that it was very uncommon to diagnose hallucinogen-induced
persistent psychosis after hallucinogen use in secure, professional settings. The
incidence of LSD-related psychosis was estimated to be about 0.8/1,000 in
experimental subjects, and one case was reported in 247 LSD users surveyed
(Cohen 1960; McGlothlin and Arnold 1971). The low incidence of such
unfavorable outcomes was the result of carefully screening volunteers, closely
monitoring their sessions, and providing supportive follow-up as indicated
HALLUCINOGEN PERSISTING PERCEPTION DISORDER
One of the most common adverse effects of hallucinogens is known collo-
quially as “flashbacks,” and in its severe form called “hallucinogen persisting
perception disorder” by physicians (American Psychiatric Association 1994).
“Flashbacks” are spontaneous, repeated, and at times continuous recurrences of
one or more of the sensory, cognitive, or emotional symptoms of the hallucino-
genic experience after an intervening drug-free period. In earlier decades,
“flashbacks” got media attention and were highlighted as a deterrent to recrea-
tional use. Most subjects having these experiences find them interesting, enjoy-
able, and time-limited. Only when such incidences cause distress and interfere
with ordinary function do people turn to clinicians. Therefore, it is not well estab-
lished how often “flashbacks” occur. In addition, because the term “flashback” has
been used in many different ways, determining the true incidence of the disorder is
even more difficult to determine. Reports from early studies on LSD users
T H E R A P E U T I C G U I D E L I N E S 7 8
(McGlothlin and Arnold 1971) suggested that subjects with less than 10
exposures report “flashbacks” at a rate of 12%, and they were less common in
medically controlled settings as compared to street users. This early observation
was recently reinforced by Halpern and Pope (2003), who also pointed out that
when LSD was used in a therapeutic or research setting, the hallucinogen
persisting perception disorder appeared less frequently than when it was used rec-
The symptoms of hallucinogen persisting perception disorder are better
defined: they most commonly consists of visual disturbances such as simple geo-
metric pseudo-hallucinations (dots, grids, zigzags, spirals, etc.); seeing halos,
bright, colorful flashes, or trails attached to moving objects; and perceiving false
motion on the edges of the field of vision. There appears to be no strict relation-
ship between the frequency of hallucinogen use and the rate of occurrence: a single
dose of LSD can cause the disorder. Stress, fatigue, sleep deprivation, dark
environment, marijuana use, depression, and anxiety are the known precipitating
or augmenting factors. This condition is typically persistent, and in some cases
remains unchanged for years after individuals have stopped using the hallucinogen
(Abraham 1983). Given that millions of people have taken hallucinogens, the
incidence of hallucinogen persisting perception disorder appears to be very
small, and there is presently no fully effective treatment.
The characteristics of the hallucinogen persisting perception disorder
suggest that hallucinogens may exert long-lasting physiological changes in the
brain with hyperexcitability of the visual system. Psychological studies found
abnormalities in visual function, supporting the hypothesis that imagery continued
to be processed although the test stimulus had been removed. This dysfunction
may arise from a destruction of inhibitory interneurons of the visual pathways
that receive serotonergic input and were overstimulated by LSD, with subsequent
excitotoxic degeneration. Preclinical research (Gewirtz et al. 2002) showed that the
phenethylamine hallucinogen 2,5-dimethoxy-4-iodophenyl-2-aminopropane
increased the expression of the brain-derived neurotrophic factor, which can pro-
vide another clue to the mechanism by which hallucinogens might exert long-
lasting changes in synaptic connections of the nervous system.
P E R S O N A LI T Y C H A N G E S
The psychedelic impact a hallucinogen may have on its users need not be
confined to the period of the acute drug effects. Having experienced the
extraordinary effects induced by the hallucinogen, many partakers feel that they
undergo deep personal changes. It is common to hear hallucinogen users testify
that they underwent major transformations and their lives were no longer the
same. The changes mentioned pertain to new psychological understandings and
personal insights; modifications of belief systems, worldviews, and perspectives
on life; and religious conversion and adherence to a spiritual lifestyle. Not infre-
quently, these effects may result in radical decisions and actions, sometimes at
variance with family members’ conventional expectations (Walsh and Vaughan
1993; Grob 2002a; Shanon 2002).
79 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
NEUROTOXIC E FFECTS
There has been an extensive debate in the literature (see Grob 2002b) on the
neurotoxic effects of hallucinogenic compounds with more focus on the
members of the phenethylamine group, especially on Ecstasy (MDMA). The
debate culminated in Science ’s retraction of an erroneous publication (Ricaurte et
al. 2002) purporting to show that even onetime use of Ecstasy (MDMA) causes
damage to the dopamine system that creates a risk of developing Parkinson’s dis-
ease later in life. Twenty percent of the studied monkeys died quickly, and
another 20% became sick with severe brain damage after their second or third
dose of the investigational drug, which later turned out to be methamphetamine.
Critics blamed the researchers’ and Science reviewers’ biased mind set for over-
looking the extreme fatality rates unusual in recreational Ecstasy (MDMA) users.
M D M A
At variance with the retracted report on dopamine neurotoxicity, extensive
studies in animals indicate that high or repeated dose Ecstasy (MDMA) exposure
can damage serotonergic nerve fibers as a result of metabolic stress (Green et al.
1995; Baggott and Mendelson 2001). The toxic effect is increased under pro-
longed physical exertion and high ambient temperature (conditions frequently
encountered in rave dancing). Similar changes can be induced by methampheta-
mine and some other phenethylamine agents (Miller and O’Callaghan 1996;
Seiden and Sabol 1996). However, there is controversy over the extent to which
analogous changes occur in humans. Ecstasy (MDMA) toxicity has not been doc-
umented in controlled research experiments with human subjects, but it has been
alleged to occur in settings outside of clinical research. When considering the
millions of users taking Ecstasy (MDMA) of unknown origin, purity, and potency
(Gore 1999; Henry and Rella 2001), serious toxicity appears to rarely happen
(less than four deaths in one million users are estimated).
Such users routinely
consume estimated Ecstasy (MDMA) doses much higher than those administered
in therapeutic protocols. Before the drug was placed into Schedule I, psychiatrists
in the United States and Europe reported using Ecstasy (MDMA) in a large num-
ber of patients, and these therapists did not report any severe adverse effects
occurring during or after MDMA-assisted psychotherapy sessions (Greer and
Tolbert 1986, 1998; Gasser 1994). There is now a considerable body of
information indicating that the likelihood of significant toxicity is very low from
the doses of Ecstasy (MDMA) used in study protocols. To date, Ecstasy
(MDMA) has been administered to over 230 people in controlled and
uncontrolled trials in clinical settings and has failed to demonstrate toxicity
(Grob et al. 1996b; Vollenweider et al. 1999; De La Torre et al. 2000; Gamma et
al. 2000; Liechti and Vollenweider 2000). There may nonetheless be legitimate
concerns about complications arising as a consequence of polydrug abuse, and
the interactions of prescription drugs and food substances with MDMA.
T H E R A P E U T I C G U I D E L I N E S 8 0
IBO GA INE
Several studies have reported cerebellar (Purkinje) cell degeneration in rats
after ibogaine administration at doses of 100mg/kg. However, the neurotoxic
effect of ibogaine appears to occur at levels higher than those used for opioid
withdrawal or recreational purpose. Moreover, rats appear to be more sensitive
to potential ibogaine neurotoxicity compared to other species (including pri-
mates). Contrary to expectations from an allegedly abusive drug, since ibogaine
has a broad receptor profile with glutamate antagonistic activity at NMDA (N-
methyl-D-aspartic acid) specific sites, that feature suggests neuroprotective
potential in stroke patients. Ibogaine was reported to protect against metham-
phetamine neurotoxicity (for review, see Alper 2001).
IND OLE AL KY LAM IN E S
Very little is known about the neurotoxicity of the indolealkylamine group; in
part because they represent the lowest frequency of use, and no controlled
studies are available. Conclusions from observational reports of sacramental use,
that contrary to expectations, the DMT–and beta-carboline–containing ayahuasca
may have protective effects (Grob et al. 1996a). Some other conjectural evidence
supports the notion that this group of hallucinogens may exert neuroprotection.
The receptor profile of the indolealkylamines hallucinogens is unique among the
classical hallucinogens for their relatively “clean” serotonin1A agonist (receptor
stimulating) property, and neuroprotective action from serotonin1A agonists have
been demonstrated in different species (De Vry 1995).
ERG OL INE S
An intermediary position is represented by the ergoline group (e.g., LSD),
where the relatively strong flashback-inducing effect may be related to their neu-
rotoxicity within the visual system (Abraham and Mamen 1996). On the other
hand, there are circumstances where LSD and other serotonin2A receptor ago-
nists were found to be neuroprotective (Farber et al. 1998).
CHE M ICA L I NTERA CTI ON CO MPLIC ATI ONS
Since the final common pathway of the classical hallucinogenic drugs is the
serotonin system, the main concern about drug interactions is primarily in terms of
the possibility of an alarming increase in serotonergic effects—a set of
symptoms known as the “serotonin syndrome,” which is characterized by exces-
sive levels of the neurotransmitter serotonin both in the brain and in the bodily
organs. Symptoms are typically initial excitement, nausea, and confusion, fol-
lowed by tremors, vomiting, convulsions, and loss of consciousness (Isbister and
Buckley 2005). The incidence of the “serotonin syndrome” is not known, since
most of the cases are mild and resolve undiagnosed. In its severe form if emer-
gency treatment is instituted (which is essentially supportive care for lack of spe-
cific antidotes), the syndrome typically resolves within 24 hours. Confusion can
last for days, and death has been reported in extreme cases because of circulatory
collapse, malignant hyperthermia, or prolonged convulsions (Settle 1998).
T H E R A P E U T I C G U I D E L I N E S 8 1
Several different drug combinations can lead to this potentially fatal condi-
tion. The most common and most dangerous is the mixture of serotonergic agents
with MAOIs (monoamine-oxidase inhibitors) of the irreversible type.
Mono-amine oxidase enzymes (MAO-A and MAO-B) are found in the brain, the
lung, the liver, and the gastrointestinal system and provide a multiple defense
line against invasions of the body from dietary monoamines, particularly tyramine,
a food component which can cause extreme high blood pressure. While inhibition
of the MAO’s action is not intrinsically life threatening—if some dietary con-
strains are maintained—fatalities from combinations of MAOIs with SSRIs
(specific serotonin reuptake inhibitors) have been reported. A mixture of a
MAOI with an SSRI results in blockages of the serotonin metabolism by
monoamine oxidation and serotonin reuptake into nerve terminals. The
production of serotonin continues unaffected while its important pathways of
elimination are shut down, causing serotonin accumulation which can increase to
Based on an animal study (Santos and Carlini 1983), it was found
that sleep-deprived subjects may have slightly increased sensitivity toward
serotonin syndrome, calling attention to a risk factor for “ayahuasca tourists”
owing to long flights and jet lag.
Among hallucinogenic compounds the Amazonian decoctum ayahuasca has
the greatest potential for a variety of chemical interactions. Ayahuasca is a hallu-
cinogenic beverage derived by boiling parts of two or more plants. The brew con-
tains beta-carbolines, which are extremely effective MAOIs, and the potent
indolealkylamine hallucinogen DMT. The beta-carbolines, however, are reversible
MAOIs, which means they are readily displaced by dietary monoamines or
endogenous serotonin, allowing them to be metabolized and thereby avoiding
accumulation of these substances to toxic levels. On the contrary, first-
generation synthetic MAOIs (such as phenelzine, tranylcypromine, and isocar-
boxazid) that are used as antidepressants in clinical practice bind tightly (irrevers-
ibly) to the enzyme and are not readily displaced. With their use, hypertensive
reactions may occur if specific dietary constraints are not maintained. The clinical
consequence of the reversible property of beta-carbolines is that strict dietary
restrictions may not be required when ayahuasca is used in its traditional formu-
lation. There are other features of beta-carbolines which may explain why reports
of hypertensive crises following the ingestion of ayahuasca have not been docu-
mented: beta-carbolines are highly selective inhibitors of MAO-A, a variant of
the enzyme (isozyme) which prefers tryptamines (including serotonin) over the
pressor agent tyramine as substrates (Yasuhara 1974) and their affinity is lower for
liver MAO compared to brain MAO. This complex mechanism would explain the
lack of any reports of peripheral autonomic stimulation associated with the
ingestion of ayahuasca in combination with sympathomimetic drugs or foods
containing tyramine (McKenna et al. 1998).
Whilst ayahuasca is less likely to induce hypertensive crises with the con-
comitant administration of sympathomimetic drugs or with tyramine-rich food-
stuffs, it still seems wise to advocate care in combining it with potentially
interacting medications and to advise a degree of caution with regard to the
dietary intake of foodstuffs likely to contain high tyramine content. These typi-
82 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
cally include fermented or processed food(since bacteria and fungi turn the
amino acid tyrosine to tyramine), such as aged cheese, smoked or cured meat,
liver products, concentrated yeast or protein extracts, soy foods, fava bean pods,
sauerkraut, tap beer, and some brands of red wine. Any protein-containing food or
beverage improperly stored or handled should be avoided (Gardner et al. 1996).
Beta-carbolines in ayahuasca also retain a potential for adverse interaction
with not only sympathomimetic drugs: its concomitant use with serotonin-
enhancing drugs (especially SSRIs) and psychostimulants (e.g., amphetamines,
MDMA, and methylphenidate) should also be avoided. People interested in using
ayahuasca are strongly cautioned not to combine this plant medicine with certain
classes of psychoactive drugs (Callaway and Grob 1998). Some of the specifi-
cally proscribed drugs include Nardil, Parnate, Marplan, Prozac, Paxil, Zoloft,
Luvox, Celexa, Lexapro, Effexor, Adipex, Phenphen, Pondimin, and Redux.
As it was previously described, serotonin syndrome is an acute crisis related to
a sudden increase of serotonin in the body. There exists a syndrome opposite to it
and related to chronic, depleted level of brain serotonin, a condition which can be
caused by tryptophan-poor diet (for example, one based on corn). Tryptophan is an
essential amino acid and the precursor of serotonin. In studies with humans and
nonhuman primates, low serotonin levels were associated with poor impulse
control, dysphoric-anxious mood, irritability, recklessness, and social ineptitude
(for review, see Bell et al. 2001). When brain serotonin is low, release of testos-
terone results in a higher rate of self-detrimental and unrestrained aggression
(Birger et al. 2003); predispositions which represent a particularly bad mind set for
psychedelic experience or community rituals.
The aboriginal tribes of the Amazon basin have developed a bland, salt,
spice, and concentrated sugar-free diet (Luna and Amaringo 1999) many
generations ago, which prohibits sexual activity and red meat, but permits cer-
tain amount of fish and poultry and promotes starchy food like manioc, potatoes,
quinoa (a grain), oats, rice, and plantain (a type of banana, which theoretically
would be prohibited by the MAOI-safety diet). Some traditions place more
emphasis on preceremony diet (even as long as six months), while other
traditions stress postceremony diet more. The traditional ayahuasca
preceremony diet is probably not for prevention of MAOI-related complications:
one does not need to follow MAOI diet for days or weeks before a ritual; it would
make more sense adhering to a MAOI-safe diet during the hours, and following
the ceremony. It is not merely healthy or for spiritual cleansing. The traditional
ayahuasca diet may serve a very rational purpose: to increase brain serotonin by
An Amazonas shaman (ayahuasquero among mestizos) definitely does not
want his/her people entering the ceremony with “serotonin depletion syndrome”
and behaving like “pests.” This can be prevented by a tryptophan-rich diet (which
can include fish, poultry, papaya, banana, avocado, spinach, cottage cheese, milk,
seeds, and nuts), with starch and without competition of amino acids from other
sources. Tryptophan needs sugar for facilitated transport into the brain, but from
complex carbohydrates (starch) and not from pure sugar. Concentrated, simple
T H E R A P E U T I C G U I D E L I N E S 8 3
sugars induce a sharp increase of insulin release, and insulin helps the transport of
rivaling (multiple chain) amino acids (not ring type like tryptophan) into the brain
which compete with tryptophan for the transport sites. Promptly activating the
brain’s serotonin receptors DMT, the psychoactive ingredient of ayahuasca, can
exert a prosocial effect, somewhat opposite to the serotonin depletion syndrome,
and fulfill the role of a “sociointegrator”—one interpretation of the indigenous
practice of using ayahuasca ceremony for “crisis resolution” in the community.
The use of ayahuasca has not been limited to indigenous or mestizo groups,
but it is regularly used by members of syncretic religious movements, whose in-
fluence is growing in the urban populations of Brazil and recently throughout the
Americas and in Europe. Based on the millions of people worldwide who are
currently undergoing treatment with SSRIs, the potential for incurring a dangerous
serotonin syndrome should not be ignored. The presence of euphoria, confusion,
vomiting, and tremor as common as initial symptoms from typical doses of
ayahuasca makes the diagnosis of “serotonin syndrome” difficult to rule out in
people on serotonergic medications.
Beta-carbolines and SSRIs are metabolized in the liver by the same isozyme
of the cytochrome P450 enzymatic clearance system denoted as CYP2D6. This
common metabolism by CYP2D6 provides another good reason to avoid the
combination of SSRIs with ayahuasca, since beta-carbolines not only delay
elimination of endogenous serotonin but also do the same with the SSRI thus
exaggerating the interaction. 5-Methoxy-DMT—a close analogue (chemical kin)
of DMT—elicits more intensive undesirable effects, and leads to a less visionary
psychedelic experience than its chemical cousin. Essentially, CYP2D6 is a highly
specific, high-affinity, high-capacity 5-methoxyindolealkylamine-O-demethylase
(Yu et al. 2003) with higher affinity for 5-methoxy-DMT than for DMT, and
represents its cardinal metabolic pathway (besides MAO). Therefore, ayahuasca
(especially pharmahuasca) preparations with high 5-methoxy-DMT
contamination can result in a very “rogue” experience in case the CYP2D6
activity is blocked or deficient. Since the antidepressants paroxetine (Paxil) and
fluoxetine (Prozac) are potent CYP2D6 inhibitors, subjects taking these SSRIs are
at risk of complex metabolic interactions.
The isozyme CYP2D6 exhibits a wide range of polymorphisms in human
populations with interindividual and inter-ethnic variations in its enzymatic
activity. This metabolic trait could account for differences in effects between
individuals who take ayahuasca and makes some ethnic groups more or less
vulnerable for ayahuasca-drug interactions and 5-methoxy-DMT effects. The
frequency of reduced function or nonfunctional gene variants of CYP2D6 is
higher in African and Oriental populations (~50%) contrasted to Caucasian and
Amerindian groups (~30%) (Bradford 2002). The presented picture of
polymorphism is not straightforward: Caucasians have higher percentage of poor
metabolizers (bimodal distribution with a subgroup of 7% at the slow end) as
compared to Orientals (1–2%), but their population metabolizes faster in general
(with more rapid metabolizers in the group). In conclusion, one may expect that
ayahuasca users of African or Oriental descent are somewhat more vulnerable to
84 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
The function of CYP2D6 is not only race-related but also age-dependent as
well. CYP2D6 activity increases rapidly after birth to reach a level equivalent to
that in the young adult, then gradually decreases and finally declines faster in old
age (Tanaka 1998). MAO-B shows a different trend with advanced age: its activity
increases (Kumar and Andersen 2004). The combination of these enzyme changes
may predispose elderly people for more adverse reactions and decreased DMT
effects, since DMT is primarily oxidized by MAO-B in the brain (Suzuki et al.
1981). We have no data regarding age effects on the active reuptake of DMT into
the brain, which would probably be more relevant for the distribution (Yanai et al.
1986) and bioavailability of DMT than the physiological, age-related increase of
MAO-B activity, since the amounts of beta-carbolines present in a typical dose
of ayahuasca are usually well above the saturation threshold for MAO
inhibition. Based on the observation of difficulties with the experience among
elderly ayahuasca users (Luis Luna, pers. comm..), I predict variation in the
active DMT transport into the brain with a decline at advanced age.
SU MM AR Y
The purpose of the above material has been to show that the hallucinogens are
much safer than is generally believed by the public and even by the professionals.
There nonetheless needs to be strong cautionary statements in the recom-
mendations for use. For instance, one might presume that ayahuasca does not
need as strict dietary restrictions as many of us might suppose because of its
reversible MAOI feature. This seems evident given the many ayahuasca tourists
who do not care too much about their diet and concomitant medications. These
involve thousands of cases with very few, questionable fatalities. The Callaway
and Grob (1998) paper is really not a report of a serious serotonin syndrome; it is
rather a necessary but overprotective warning. The case is that mild-to-moderate
serotonin syndrome is indistinguishable from ayahuasca effects (i.e., its vegetative
symptoms at the onset essentially represent a mild serotonin syndrome), making
the differential diagnosis difficult to ascertain.
GENERAL GUIDELINES FOR THERAPEUTIC USE AND FUTURE
Classic hallucinogens are classified in a combined effort by the Department
of Justice and the Department of Health and Human Services as Schedule I
drugs, which means a high potential for abuse, with no medical utility, or lack of
safety for use of the drug under medical supervision (United States Code 2000).
The purpose of this chapter and the whole volume is to point out that none of
these statements are defensible. There clearly are instances where a Schedule I
hallucinogen can be used safely and does have medical utility (at least in terms of
clinical investigation). Under Schedule I, classic hallucinogens are rated worst
than the more dangerous and addictive cocaine and amphetamines (Schedule II
drugs). Since hallucinogenic agents can have medical use, they should be
switched to Schedule II. Alternatively, there ought to be some sort of Ia
Schedule, which means that one would need special training or certification to
use a Schedule I drug (Strassman pers. comm.). What that training and
T H E R A P E U T I C G U I D E L I N E S 8 5
certification would involve is a complicated issue. Perhaps something akin to
psychoanalytic certification is a useful analogy: someone needs to know what
the drugs are and do, and must be very well versed in their own psychology and
Owing to the diversity of hallucinogenic compounds, only general guide-
lines can be provided for their clinical use within the constraints of this chapter.
Since no hallucinogen has FDA approval for therapeutic indications for the
general public, strict guidelines used in experimental protocols are applicable.
An exception is ketamine, which is currently Schedule III. However, its use is
approved for anesthesia, and off-label use of a controlled substance is very
murky; such practices with ketamine may require a certificate of “conscious
For particular drugs and individual cases, the investigator or the therapist has
to use clinical judgment based on a cost-benefit analysis serving the subjects’ best
interest and in adherence with the directives of local ethics committees. These
may include review of the proposed protocol by an ethically and scientifically
competent institutional board and acquisition of informed consent from study
participants. The informed consent must include, among other considerations: a
description of the protocol understandable to a nonspecialist reader; a proper dis-
cussion of possible risks and benefits; and a discussion of treatment alternatives;
and a statement describing the extent, if any, to which confidentiality of records
identifying the subject will be maintained (Code of Federal Regulations 2006).7
The application of these considerations may justify the experimental or therapeutic
use of hallucinogens in the given situation.
Inclusion Criteria for participants, the Outcome Measures of treatment, and
the Monitoring Procedures are dependent on therapeutic goals or the purpose of
the particular study, but common elements of a clinical investigational protocol
using classical hallucinogenic agents can be generalized as follows.
Subjects enrolled into hallucinogenic protocols have to undergo a detailed
psychiatric diagnostic interview (preferably structured one), and mental disorder
comorbidity, substance abuse problems, or a personal or family history of psy-
chosis has to be ruled out. Individuals who carry two copies of the Val allele of
the COMT enzyme should be considered for exclusion from cannabis protocols.
Participants must be free of any clinically significant comorbid medical illness
(other than the targeted one) based on physical examination and routine blood
testing. They should not require on a regular basis any prescription or over-the-
counter medications interfering with the hallucinogen. Any potentially dangerous
medication they may have taken should have been stopped for long enough to
allow for their elimination prior to start the administration of the study drug.
Women who are pregnant, lactating, or unwilling/unable to practice medically
acceptable birth control during the study should also be excluded.
86 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
Subjects are required to refrain from the use of alcohol, drugs of abuse,
over-the-counter medications, and medicinal natural products for the duration of
the treatment. Dietary recommendations may apply to the use of compounds
with MAOI content (such as ayahuasca preparations), as it was discussed above.
In the latter case, six-hour fasting may be required prior to intake for mitigation of
nausea and vomiting.
Several special procedures are necessary in order to minimize risk to subjects
who participate in clinical studies with hallucinogens. During the early phase of
testing, each subject may need constant observation; at the initiation of therapy,
they may need to be kept in the hospital overnight and be assessed by the inves-
tigator prior to leaving the following day. If subjects are found to be at risk of
complications from the procedure at the projected time of discharge, they have to
be kept in the hospital until they are felt to be safe. If complications should result
during testing, the investigators will be available to treat them as they arise (i.e.,
psychosis, abnormal mood states, panic attacks, seizures, and others).
FUTURE RESEARCH DIRECTIONS
We are limited in our ability to address all possible complicating factors in the
use of hallucinogens as therapies or research medications because of the limited
research designs which have thus far been employed. Ascribing adverse effects
to a particular hallucinogenic agent (or any kind of drug) is not simple if one is
bound to scientific scrutiny. A causal relationship implies a fixed temporal sequence
between drug and effect and conclusions based on well-established evidence
linking the two. In pharmacological research, different study levels with increasing
scientific rigor are instituted for evaluation of a drug.
UNCONTROLLED CASE REPORTS
This type of design is at the low end of scientific value. Although without stat-
istical power, case reports (e.g., Savage et al. 1988) often become the seed from
which more systematic inquiries blossom. In hallucinogenic research, case reports
fuel protocols with solid designs for the evaluation of beneficial and adverse drug
effects. The exaggerated and at times even fabricated cases in media which capture
public attention are even able to influence professional attitudes but do not have
scientific value. Nevertheless, those have been dominating the public arena thus far.
The controversy is clear: would anyone judge the usefulness of an FDA approved,
pharmaceutical company marketed drug based on their abuse, or careless use
outside of medical settings? Probably not. Until very recently, hallucinogens could
not profit from being tested under neutral academic attention with advanced
scientific methods, and mostly have been judged based on reports of their abuse.
Not even the “benefit of doubt” has been applied to their case.
T H E R A P E U T I C G U I D E L I N E S 8 7
CASE SERIES, CASE-CONTROLLED DESIGNS
Low levels of validity are represented by case series (e.g., Gill et al. 2002),
case-controlled designs, such as comparisons of groups by an unstructured inquiry
into their history. In case-control studies, the researcher gathers the data on the
dependent variable (e.g., adverse effects) and then looks into the past of the partic-
ipants to classify them. A good number of these studies are now available, and the
majority of literature data on hallucinogen abuse-related psychiatric and medical
disorders are based on this kind of approach. Particular concern for any of the
above methods is the difficulty in securing a group of hallucinogen users who are
free of unrelated psychopathology and/or other psychoactive drug use.
At higher levels of validity are open label trials (e.g., Attal et al. 2004), which
provide observational data on the clinical effects of known substances (e.g.,
without double-blind). Studies with an open label design can be randomized trials,
but some do not include a comparison group; therefore, no randomization can be
accomplished in these cases. Open label trials lack the strength of a blind design
and so are prone to investigator’s bias, but the validity of this approach is
supported by a controlled dose regimen, prospective design, and statistical analysis
of the recorded data. There is no randomization at all in observational studies, where
the allocation of treatment is not fully under the control of the investigator.
Observational studies are more likely to require difficult statistical
adjustments because of the potential for large imbalances. In the research of
hallucinogen-related complications, studies with this methodological level are
DOUBLE-BLIND RPCT (RANDOMIZED, PLACEBO CONTROLLED TRIALS)
These represent the highest level of validity with the random and blind
assignment of subjects to a drug cohort or a placebo control group. This golden
standard designed for medication development (double-blind, randomized,
rigorous trials) is rarely accomplished in hallucinogenic research. Since the end of
the 20-year moratorium on human experimentation with hallucinogens, a series
of new studies has emerged utilizing careful attention to experimental design.
remarkable example is the replication of the preeminent Good Friday Experiment
(Pahnke 1963) by a group from the Johns Hopkins Hospital (Griffiths et al. 2006;
reprinted here in Volume 2) for psilocybin’s effect in occasioning mystical expe-
riences. Griffiths’ group advanced the methodology of the pioneering study and
improved the set and settings as well. Both studies were double-blind, active
placebo-controlled trials, but the blind in the Good Friday Experiment was easily
broken during the session by the participants’ psychedelic experience. Another
limitation of the Pahnke study was that it was conducted in a group setting. The
Johns Hopkins study used better blinding and comparison control procedures,
applied empirically validated measures of mystical experience, and assessed
effects in individual participants undisturbed by group interactions. Besides a suc-
cessful replication of the Good Friday Experiment (its results were even better), an
88 PSYCHEDELIC MEDICINE: SOCIAL, CLINICAL, AND LEGAL PERSPECTIVES
important finding of the Griffiths study was that with careful volunteer screening
and preparation, and when sessions are conducted in a comfortable, well-
supervised setting, a high dose of psilocybin can be administered safely.
This renaissance is promising but has not yet produced an abundance of
well-controlled trials on the putative dangers of hallucinogenic drugs. In order to
adequately answer safety concerns related to these compounds, one may need
Phase II and III clinical trials.
Clinical trials belonging to the RPCT group and addressing safety and effi-
cacy issues are designated as Phase I, II, or III, based on the type of questions that
study is seeking to answer.
In Phase I studies, investigators test a new drug in a small group of healthy
volunteers (20–60) for the first time to evaluate its safety, determine a safe dosage
range, and identify side effects.
In Phase II trials, the study drug is given to a larger group of ill people (100–
400) to further evaluate its safety and to see if it is effective.
In Phase III clinical trials, the size of the treatment group is increased to a
larger number of patients (1,000–4,000) to confirm the effectiveness of the drug,
monitor its adverse effects, compare it to commonly used treatments, and collect
information that will allow its safe use.
Today we are witnessing the entrance of hallucinogens (ibogaine, marijuana,
MDMA, and psilocybin) into the Phase II stage of well-controlled trials. As an
FDA approved anesthetic, ketamine has already passed these phases, and off-
label trials are under way (Zarate et al. 2006). The cost of a Phase III study is so
expensive, that usually industry sponsored trials can afford that investment.
Appropriate information can also be gained in a cost-effective manner via post-
marketing (post-approval) trials (not necessarily RPCT), representing the IVth
phase in the development of a therapeutic agent.
CONCLU S I O NS
It is apparent that more and better controlled research (at least Phase II) is
needed to clarify the adverse effects of hallucinogens. That kind of research would
need enrollment of healthy human volunteers. While rigid administrative regula-
tions in the United States are loosening up for the therapeutic use of hallucinogens
in severely ill patients, the United States is lagging behind Switzerland and Ger-
many where hallucinogen research is not restricted to sick people. Drug safety
cannot be reliably evaluated only on individuals with compromised health.
In summary of our current knowledge, even when hallucinogens are ingested
outside of controlled medical, ceremonial, or research settings, these agents have a
relatively low potential to be harmful. Nonetheless, ill-conceived hallucinogen
experimentation may induce unstable affect and even precipitate psychotic
breaks, especially in individuals with dormant or preexisting psychopathology.
What follows is that the recreational use of hallucinogens has not been proven to
T H E R A P E U T I C G U I D E L I N E S 8 9
The situation is less forbidding under controlled settings, where careful
screening of participants, close monitoring of the sessions, and providing follow-
up minimize the incidence of serious adverse events to a very low level, below
the reasonably accepted threshold. Certainly, one should not judge a drug from its
misuse since that way of evaluation is scientifically incorrect, and there is a
possibility of well-conducted studies of both therapeutic and socially acceptable
use. With the FDA approving several hallucinogen treatment trials and the
Supreme Court siding with the União do Vegetal in the ayahuasca case, that pos-
sibility is on a cautious path of realization.
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5. One may argue that the brain has other adaptive mechanisms remaining unaltered and
counteracting the dangerous outcome: self-regulatory autoreceptors can shut down the release of
serotonin into the synaptic cleft, and/or another serotonin metabolizing enzyme, the extracellularly
located HIOMT (hydroxyindole-O-methyltransferase) enzyme (which is similar to the COMT enzyme
mentioned previously in the text) can catalyze deactivation of the excessive neurotransmitter.
However, the autoreceptor-mediated feedback regulation becomes less effective after chronic use of
SSRIs (Blier et al. 1998), some drugs (such as haloperidol) can block HIOMT, and some people may
have genetically deficient HIOMT (Yi et al. 1993). Therefore, in very rare instances though, the
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