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P A R T 4
Drugs acting on the central and peripheral nervous systems
cystitis, sexual dysfunction, urgency and impotence.
Respiratory changes may include cough, dyspnoea,
upper respiratory infections and pharyngitis. Other
reported effects are sweating, rash, fever and pruritus.
Recent studies have linked the incidence of suicidal
ideation and suicide attempts to the use of these drugs in
children and adolescents (see Box 21.5).
Clinically important drug–drug interactions
Because of the risk of serotonin syndrome if SSRIs are
used with MAO inhibitors, this combination should be
avoided, and at least 2 to 4 weeks should be allowed
between use of the two types of drugs if a person is switch
ing from one to the other. In addition, the use of SSRIs
with TCAs results in increased therapeutic and toxic
effects. If these combinations are used, people should
be monitored closely, and appropriate dose adjustments
should be made. For more information see Box 21.6.
Childhood suicide and antidepressants
In 2004, the Australian Government Adverse Drug
Reactions Advisory Committee (ADRAC) reviewed US Food
and Drug Administration (FDA) and UK Committee on
Safety of Medicines (CSM) reports around increased risk
of suicidal behaviour in children being treated with SSRIs.
It was concluded that there was evidence that SSRIs could
increase risk of suicidal ideation, attempts and self-harm.
ADRAC recommended that use of SSRIs in children or
adolescents should only be considered in the full context
of the person’s overall management.This includes caution
and careful monitoring of behaviour and compliance,
and should include cognitive behavioural therapy if
available.The choice to prescribe SSRIs needs to include
consideration of published trial data, product information
and manufacturer warnings about use in children and
adolescents. Finally, it is advised that SSRIs should not
be abruptly ceased in these groups. See
/
archive/committees-adrac-ssri-040617.htm#.Uy94K87C_Q8.
The evidence
BOX 21.5
People being treated with SSRIs are at an increased risk
of developing a severe reaction, including serotonin
syndrome, as well as an increased sensitivity to light
if they are also taking St John’s wort. Because this
herbal therapy is often used to self-treat depression, it is
important to forewarn any person who is taking an SSRI
not to combine it with taking St John’s wort.
Also caution people that there is an increased
risk of seizures if evening primrose is used with
antidepressants, and people should be cautioned against
this combination. Interactions have also been reported
when antidepressants are combined with ginkgo,
ginseng and valerian. People should be cautioned
against using these herbs while taking antidepressants.
Herbal and alternative therapies
BOX 21.6
Care considerations for people receiving
selective serotonin reuptake inhibitors
Assessment: History and examination
■
■
Assess for any known allergies to SSRIs
to avoid
hypersensitivity reactions
; severe depression or
suicidality,
which could be exacerbated by these
drugs
; impaired liver or kidney function,
which
could alter metabolism and excretion of the drug
;
and diabetes mellitus. Find out whether women are
pregnant or breastfeeding
because caution should
be used in these situations and drug use limited.
■
■
Assess temperature and weight; skin colour and
lesions; affect, orientation and reflexes; vision;
blood pressure and pulse; respiratory rate and
adventitious sounds; and bowel sounds on
abdominal examination
for baseline status before
beginning therapy and for any potential adverse
effects.
Also obtain renal and liver function tests.
■
■
Refer to Critical thinking scenario for a full
discussion of care for a person who is dealing with
depression.
Implementation with rationale
■
■
Arrange for lower dose in elderly people and in
those with renal or hepatic impairment
because of
the potential for severe adverse effects.
■
■
Monitor the person for up to 4 weeks
to ascertain
the onset of full therapeutic effect before adjusting
dose.
■
■
Establish suicide precautions for severely depressed
people and limit the quantity of the drug dispensed
to decrease the risk of overdose.
■
■
Administer the drug once a day in the morning
to achieve optimal therapeutic effects.
If dose
is increased or if the person is having severe GI
effects, the dose can be divided. Serious name
confusion has been reported with some of the
SSRIs (see Focus on safe medication administration
in the section Contraindications and cautions).
■
■
Suggest that the person use barrier contraceptives
to prevent pregnancy while taking this drug
because serious fetal abnormalities can occur.
■
■
Provide comfort measures
to help the person
tolerate drug effects.
These may include voiding
before dosing, instituting a bowel program as
needed, taking food with the drug if GI upset
is severe or environmental control (lighting,
temperature, stimuli).
■
■
Provide thorough teaching, including the drug
name, prescribed dosage, measures for avoidance
of adverse effects and warning signs that may
indicate possible problems. Instruct people about
