Home' Australian Pharmacist : Australian Pharmacist August 2016 Contents Australian Pharmacist August 2016 I ©Pharmaceutical Society of Australia Ltd.
This is the second part of a three
part series discussing drug abuse.
To a certain degree, any medication
possessing psychoactive effects has
the potential for abuse if taken in large
Part one focussed on cough and
cold preparations. In Part two the
focus moves to antihistamines,
antidepressants and anticonvulsants.
While practitioners and pharmacists
exercise caution when dealing with
narcotics, other drugs may not always
receive adequate attention. They can slip
by unnoticed; viewed as innocuous and
necessary therapy. Indeed the majority
of these drugs are taken appropriately
While the majority of Schedule 4
prescriptions and over-the-counter
(OTC) medications are taken
appropriately; abuse of drugs for their
psychoactive effects occurs. Addicts
search for effects that include Sedation,
Hallucinations, increased Energy,
Euphoria and Relaxation. They do this for
the SHEER thrill of it.
The abuse of benztropine (benztrop or
cogentin) and diphenhydramine is well
documented. Although anticholinergics
can be abused, trihexyphenidyl (artane) is
most frequently used. All anticholinergics
are abused in high doses for their
euphoric, hallucinogenic and stimulant
effects. The misuse of anticholinergics by
people with serious mental illness may be
as high as one in five.
New atypical antipsychotics affect
many neuro-receptors with a variety of
potential affects. Many people exploit
these affects by either consuming
excessive dosages or combining them
with a cocktail of other drugs.
Quetiapine is abused for its anxiolytic and
sedative effects. Oral abuse finds an addict
taking between 800 mg and 1200 mg as a
single dosage. Drug-seeking, compulsion
and diversion occur.
Quetiapine’s rapid dissociation from the
dopamine receptor has been theorised
to contribute to the drug’s abuse possibly
through relatively lower potency
and decreased residence time at the
dopamine receptor. This mechanism also
contributes to quetiapine’s lower risk of
extrapyramidal side effects, which make
the drug easier to tolerate.
Although dopamine is a factor in
substance abuse and treatment of
psychotic disorders, other neuro-
pharmacologic mechanisms must
be considered. Second generation
antipsychotics (SGAs) are theorised
to cause dopamine release in the
frontal cortex through effects
as 5-HT1A agonists and 5-HT2A
antagonists. Antagonism of alpha-
adrenergic and histaminic receptors may
account for these agents’ anxiolytic and
Misuse of anticholinergic agents has
been reported for >50 years. Psychiatric
patients have been reported to increase
use of anticholinergics for their movement
side effects as well as hallucinogenic effects.
If a patient is abusing an SGA, a physician
needs to consider either switching to an
antipsychotic with the potential for less
abuse or limiting the supply of the drug.
These include aripiprazole, diazepam,
haloperidol, olanzapine, quetiapine and
risperidone. Dependence and withdrawal
have been documented where a hospitalised
patient, unable to control his intake,
experienced withdrawal upon stopping.
Street names for quetiapine include: quell,
baby heroin or jailhouse heroin.
Several reports include descriptions
given by abusers of the effects they
have experienced from olanzapine. They
showed that sedation (or similar effects)
escalated to dosages of 40–50mg/
day. The levels produced a ‘buzz’ that
was accentuated by the concomitant
use of alcohol and/or benzodiazepam,
producing a heightened sense of euphoria.
When attempting to stop, feelings of
nervousness, insomnia, and unbearable
Antidepressants with anticholinergic or
dopaminergic effects pose the greater
risk but those with sedative or stimulating
properties still possess the potential
Monoamine oxidase inhibitors
Monoamine oxidase inhibitors (MAOIs)
inhibit the activity of the iso-enzymes
monoamine oxidase-A and monoamine
oxidase-B, preventing the breakdown
of monoamine neurotransmitters thus
increasing their availability. The main
substrates for MAO-A are epinephrine,
nor-epinephrine, and serotonin. The
main substrates for MAO-B are
phenylethanolamine, tyramine, and
benzylamine. Dopamine is metabolised
by both iso-enzymes. Some MAOIs are
selective for either. Some are non-selective,
inhibiting both MAO-A and MAO-B.
David Clancy is a community pharmacist at Westmead
in Sydney, NSW.
The necessity of teaching mankind not to take drugs and
medicines is a duty incumbent upon all those who know their
uncertainty and injurious effects ..
Potential abuse from
unexpected sources (Part 2)
BY DAVID CLANCY MPS
Charles Armbruster MD
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