340
P A R T 4
Drugs acting on the central and peripheral nervous systems
Contraindications and cautions
Antipsychotic drugs are contraindicated in the presence
of underlying diseases
that could be exacerbated by the
dopamine-blocking effects of these drugs.
They are also
contraindicated in the following conditions,
which can
be exacerbated by the drugs
: central nervous system
(CNS) depression, circulatory collapse, Parkinson’s
disease, coronary disease, severe hypotension, bone
marrow suppression and blood dyscrasias. Prolongation
of the QT
c
interval is a contraindication to the use of
ziprasidone which can further prolong the QT
c
interval,
leading to increased risk of serious cardiac arrhythmias.
Antipsychotics are contraindicated for use in elderly
people with dementia
because this use is associated
with an increased risk of cardiovascular events and
death.
In 2005, the US Food and Drug Administration
(FDA) issued a public health advisory regarding the use
of antipsychotics after post-marketing studies showed
that when these drugs were used to control behavioural
symptoms of dementia in older adults, the people being
treated experienced increased cardiovascular events and
death. None of these drugs is approved for this use, but
it was common practice in many settings to use them,
off-label, to establish behavioural control of people with
dementia. Antipsychotics now have a black-box warning
on the prescribing information outlining this safety
information and contraindication.
Caution should be used in the presence of medical
conditions
that could be exacerbated by the anticholin-
ergic effects of the drugs
, such as glaucoma, peptic ulcer
and urinary or intestinal obstruction. In addition, care
should be taken in people with seizure disorders
because
the threshold for seizures could be lowered
; in people
with thyrotoxicosis
because of the possibility of severe
neurosensitivity
; and in people with active alcoholism
because of potentiation of the CNS depression.
Other situations that warrant caution include mye-
lography within the last 24 hours or scheduled within
the next 48 hours
because severe neuron reaction to
the dye used in these tests can occur,
and pregnancy or
breastfeeding
because of the potential of adverse effects
on the fetus or neonate
. Antipsychotic agents should be
used only if the benefit to the mother clearly outweighs
the potential risk to the fetus or baby. Because children
are more apt to develop dystonia from the drugs,
which
could confuse the diagnosis of Reye’s syndrome
, caution
should be used with children younger than 12 years of
age who have a CNS infection or chickenpox.
The use of
antipsychotics may result in bone marrow suppression,
leading to blood dyscrasias
, so care should be taken with
people who are immunosuppressed and those who have
cancer.
Antipsychotic drugs
The ways in which people in certain cultural groups
respond to antipsychotic drugs—either physiologically
or emotionally—may vary.Therefore, when a
pharmacological regimen is incorporated into overall
care, healthcare providers must consider and respect an
individual’s cultural beliefs and needs.
• African Americans respond more rapidly to
antipsychotic medications and have a greater risk
for development of disfiguring adverse effects,
such as tardive dyskinesia. Consequently, these
people should be started off at the lowest possible
dose and monitored closely. African Americans also
display a higher red blood cell plasma lithium ratio
than Caucasians do and they report more adverse
effects from lithium therapy.These people should be
monitored closely because they have a higher potential
for lithium toxicity at standard therapeutic ranges.
• People in Asian countries, such as India,Turkey,
Malaysia, China, Japan and Indonesia, receive lower
doses of neuroleptics and lithium to achieve the same
therapeutic response as seen in people in Australia and
New Zealand.This may be related to these individuals’
lower body mass as well as metabolic differences.
• Arab people metabolise antipsychotic medications
more slowly than Asian people do and may require
lower doses to achieve the same therapeutic effects as
in Caucasians.
• Individuals in some cultures use herbs and other folk
remedies, and the use of herbs may interfere with
the metabolism of Western medications.The nurse or
midwife should carefully assess for herbal use and be
aware of potential interactions.
Cultural considerations
BOX 22.3
In prescribing for the elderly, the balance between risks
and benefit should be considered before prescribing
antipsychotic drugs. In elderly adults with dementia,
antipsychotic drugs are associated with a small increased
risk of mortality and an increased risk of stroke or
transient ischaemic attack. Furthermore, elderly adults
are particularly susceptible to postural hypotension
and to hyperthermia and hypothermia in hot or cold
weather. It is recommended that antipsychotic drugs
should not be used in elderly adults to treat mild
psychotic symptoms. Initial doses of antipsychotic drugs
in the elderly should be reduced (to half the adult dose
or less), taking into account factors such as the person’s
weight, co-morbidity and concomitant medication.
Treatment should be reviewed regularly.
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BOX 22.4
Antipsychotic drugs and the older
person
