Second edition

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basal ganglia, and cerebellar cortex, and recent data suggest
that different polymorphisms in the gene for CB1 may
confer different risks for the development of cannabis
addiction (Hopfer et al. 2006).
Differential diagnosis
Uncomplicated intoxication with cannabis may be mimicked
by intoxication with alcohol, sedative–hypnotics,
inhalants, and opioids, and cannabis intoxication complicated
by psychosis or delirium may be confused with hallucinogen
or phencyclidine intoxication; furthermore, many
patients may present with a mixed intoxication, having utilized
both cannabis and one or more of these other substances.
History and urine drug screens may be required to
make the differential diagnosis.
Treatment
Uncomplicated intoxication generally requires only observation
until the intoxication has passed. Anxiety, if troubling,
may be relieved by diazepam, in a dose of 10 mg.
Psychosis, if problematic, may be treated with a dose of an
antipsychotic, such as 5 mg of haloperidol or 1–2 mg of
risperidone, with repeat doses as needed. Delirious
patients should be closely monitored until the delirium has
passed, and may be treated as outlined in Section 5.3.
Cannabis withdrawal generally does not require treatment.
The overall goal of treatment in abusers and addicts is
abstinence, and various forms of psychotherapy have been
attempted. Unfortunately, many adolescents and young
adults simply see nothing wrong with their use, and often
drop out of treatment.
21.9 OPIOIDS
An opiate is any intoxicant normally found in opium. The
term ‘opioid’ is more general and refers to any substance,
either natural or synthetic, that has effects similar to
opium.
Opium is obtained from the juice of the poppy plant, and
two opiates are found within opium, namely morphine and
codeine. Synthetic and semi-synthetic derivatives include
heroin, oxycodone, hydromorphone, meperidine, pentazocine,
methadone, and buprenorphine: these last two
derivatives, although often used in the treatment of opioid
withdrawal and addiction, may also be used for intoxication
(Torrens et al. 1993). Of all of the opioids, oxycodone and
heroin are the most commonly used for intoxication.
Although these drugs may be taken orally for intoxication,
most users prefer a parenteral route as the effect is
more immediate and intense; tablets may be crushed, dissolved,
and filtered (often utilizing cigarette filters) to yield
a more or less adulterated and contaminated liquid, which
21.9 Opioids 671
is then injected. Most addicts progress from ‘skin popping’,
or subcutaneous injection, to ‘mainlining’ the drug
intravenously. Occasionally heroin may be snorted or
smoked, or, in the process known as ‘chasing the dragon’,
heated, with subsequent inhalation of the heroin vapor.
Clinical features
Intoxication with opioids is intensely seductive. Within
moments of intravenous injection, the user may be
rewarded by an intense ‘rush’. The body is suffused with
warmth, and orgasmic sensations may be experienced. In
less than a minute the rush tends to pass, to be replaced by
a drowsy, vaguely euphoric feeling that may last for hours
and which is accompanied by difficulty with concentration
and dysarthria. The pupils are generally constricted, peristalsis
is slowed, and constipation ensues; urinary hesitancy
or retention may also occur.
Meperidine and pentazocine intoxication have distinctive
features. Meperidine is metabolized to normeperidine, and
this metabolite may cause agitation, tremor, mydriasis,
increased deep tendon reflexes, and, occasionally, myoclonus
or seizures (Kaiko et al. 1983). Pentazocine intoxication,
when high doses are utilized, may be accompanied by dysphoria,
anxiety, hallucinations, and bizarre thoughts, along
with dizziness and diaphoresis (Challoner et al. 1990).
Overdoses of opioids are not uncommon. The purity of
‘street’ heroin varies widely, and the unwary user may unintentionally
take a lethal amount; furthermore, some addicts,
after a period of abstinence during which tolerance is lost,
may resume use with a dose that, although prior to the loss
of tolerance produced only intoxication, is now sufficient to
cause overdose. Overdose itself is characterized by stupor or
coma, accompanied by hypotension and respiratory depression.
Pupils are initially pinpoint; however, with the advent
of cerebral anoxia, mydriasis appears. Pulmonary edema
and seizures may occur, and death is usually due to respiratory
arrest. Those who survive may be left with an anoxic
dementia or sequelae of watershed infarctions.
Tolerance may develop to almost all of the effects of
opioids (with the exception of miosis and constipation)
and addicts may progressively increase their doses to
obtain intoxication, sometimes to stunning levels of a
gram or more of morphine.
Withdrawal is characterized initially by a sense of
uneasiness and a craving for the drug; soon after, yawning,
lacrimation, and rhinorrhea appear, accompanied in some
cases by diaphoresis. After several hours, patients may fall
into a restless sleep known as ‘yen’ sleep. Upon awakening,
all of the earlier symptoms intensify and patients become
irritable, dysphoric, restless, and demanding. Patients
begin to experience waves of goose flesh that may be so
severe that they resemble the skin of a plucked turkey, an
appearance that prompted the phrase ‘going cold turkey’.
Intense bone and muscle pain, especially in the back, arms,
and legs, also occurs, and patients may engage in seemingly