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CONTINUING PROFESSIONAL DEVELOPMENT
of nocturnal choking.33 Treatment
options include non-pharmacological
interventions (e.g. sugar-free/
dentist-approved chewing gum) to
promote swallowing during daytime;
or use of pharmacological agents
such as centrally acting alpha2
adrenergic agonists (e.g. clonidine),
or anticholinergics (e.g. atropine and
No particular treatment has
been found to be more beneficial than
another, and treatment choice should
be based on consumer preference and
of oral anticholinergics may further
exacerbate the anticholinergic effects
of clozapine, which is an important
consideration given clozapine’s potential
to cause constipation.32
Constipation occurs in more than
10% of clozapine users.
lead to the development of ileus
impaction, intestinal obstruction and
faecal impaction, which can be life
threatening in rare instances.
important to prevent constipation
and intervene as early as possible; this
should be a regular discussion point
with consumers taking clozapine at
each supply interval. Pharmacists
should also ensure that instances of
constipation are adequately resolved.
Depending on constipation severity,
pharmacists should recommend
treatment as per standard APF23 and
If the consumer is
using a dose administration aid (DAA)
it is important to think of constipation
treatment options that can be added
to the DAA to ensure adherence
(i.e. using a tablet form instead of a
sachet or liquid if this is appropriate).
3. Weight gain
As with many other antipsychotics,
weight gain is a particular problem
with clozapine. Pharmacists should
work with consumers to plan and
action weight-related goals, offer
associated monitoring (e.g. body mass
index (BMI), waist circumference, and
fasting blood glucose monitoring), as
well as providing referrals to associated
primary care providers (e.g. a dietitian).
J. Change in condition
Enquiring about any changes to the
person’s physical and mental wellbeing,
and how they are managing in general,
is important to assess medication
efficacy, adverse effects of medication,
and to promote a collaborative
relationship between the pharmacist
and the consumer. Inviting the
consumer to be an active participant in
their care can also influence adherence
and quality of life.
a) Drug interactions
Clozapine is a substrate for
P-glycoproteins, particularly CYP1A2
will interact with any substance
which affects demand or expression
levels of these proteins. For example,
the use of metabolic inhibitors such
as fluvoxamine, ciprofloxacin and
erythromycin can increase the risk
of adverse effects and toxicity of
clozapine. Use of metabolic inducers
(e.g. phenytoin and carbamazepine)
can reduce clozapine blood levels
and subsequent efficacy.
caution must also be used if clozapine is
prescribed with other medicines which
may lower WCC (e.g. chlorpromazine).
b) Smoking cessation
Smoking rates for people with
schizophrenia are much higher than
for the Australian general population.
The polycyclic aromatic hydrocarbons
in cigarette smoke induce CYP enzymes,
particularly CYP1A2 and CYP2B6.
CYP1A2 activity can be significantly
higher in an individual who smokes more
than 20 cigarettes a day.
is metabolised by CYP1A2, any change
in a person’s smoking behaviour has the
potential to affect clozapine blood levels.
Pharmacists are in an ideal position to
check a person’s stage of change and
to discuss current smoking habits.
Any changes need to be in consultation
with the monitoring prescriber; the
clozapine serum level should be checked
and the clozapine dose may need to be
Tapering of cigarettes and the use of
nicotine replacement therapy (NRT) is
preferred for people with schizophrenia;
use of other pharmacological
methods, such as varenicline, is
contraindicated in consumers with
a history of psychotic illness.
NRT options will depend on consumer
considerations and preferences; the
Australian Pharmaceutical Formulary
and Handbook, 23rd edition (APF23)
guidelines, and services such as Quitline
(Tel: 13 78 48) are helpful resources.
c) Caffeine consumption
As sedation is a common adverse effect
of clozapine, increased consumption
of caffeine is common.
45 Caffeine and
clozapine are both substrates for
CYP1A2. Several studies have shown
altered clozapine levels when caffeine
consumption is increased, therefore,
changes in consumption levels can
affect clozapine’s efficacy or risk of
It is recommended
that pharmacists discuss caffeine
consumption, particularly drinks with
high sugar and caffeine content in
conjunction with normal tea, coffee and
nicotine, with people taking clozapine.
A pharmacist can safely supply
clozapine after considering all of the
Recent changes to clozapine
prescription-claiming policy mean that
Australian pharmacists will be able to
supply clozapine within the community
This guide serves as a starting point for
community pharmacists considering
this service. However, continuing
discussions and sharing of information
will allow this service to develop further.
Further dialogue is needed around
when to contact the consumer’s support
team, the 48-hour rule in relation to
blood counts and adherence, when not
to supply, emergency-supply situations
and prescription requirements.
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