C H A P T E R 2 1
Antidepressant agents
325
■■
The MAO inhibitors prevent the breakdown of
noradrenaline and 5HT by monoamine oxidase,
leading to an increased level of these biogenic amines
in the synaptic cleft. This accumulation of the amines
is thought to relieve the signs and symptoms of
depression.
■■
People taking MAO inhibitors need to avoid foods
high in tyramine to prevent serious increases in blood
pressure and hypertensive crises.
SELECTIVE SEROTONIN REUPTAKE
INHIBITORS
Selective serotonin reuptake inhibitors (SSRIs)
(Table 21.4), the newest large group of antidepressant
drugs, specifically block the reuptake of 5HT, with little
to no known effect on noradrenaline. Because SSRIs do
not have the many adverse effects associated with TCAs
and MAO inhibitors, they are a better choice for many
people. SSRIs include fluoxetine (
Prozac
), the first SSRI;
citalopram (
Cipramil
); duloxetine (not available in New
Zealand) (
Cymbalta
), the newest SSRI; escitalopram
(
Lexapro
), fluvoxamine (not available in New Zealand)
KEY POINTS
Care considerations for people receiving
monoamine oxidase inhibitors
Assessment: History and examination
■
■
Assess for any known allergies to these drugs
to
avoid hypersensitivity reactions
; impaired liver or
kidney function
that could alter the metabolism
and excretion of the drug
; cardiac dysfunction;
GI or GU obstruction,
which could be exacerbated
by the drug
; surgery, including elective surgery,
because the effects of changes in noradrenaline
levels are unpredictable following surgery
; seizure
disorders; psychiatric conditions or suicidality;
and occurrence of myelography within the past
24 hours or in the next 48 hours
to avoid the
possibility of severe reactions
.
■
■
Determine whether women are pregnant or
breastfeeding
because these drugs should not be
used during pregnancy or breastfeeding.
■
■
Assess temperature and weight; skin colour and
lesions; affect, orientation, and reflexes; vision;
blood pressure, including orthostatic blood
pressure; pulse and perfusion; respiratory rate
and adventitious sounds; and bowel sounds on
abdominal examination
to determine baseline
status and for any potential adverse effects
before beginning therapy.
Also obtain an
electrocardiogram and renal and liver function tests.
Implementation with rationale
■
■
Limit drug access to a potentially suicidal person
to decrease the risk of overdose.
■
■
Monitor the person for 2 to 4 weeks
to ascertain
the onset of the full therapeutic effect.
■
■
Monitor blood pressure and orthostatic blood
pressure carefully
to arrange for a slower increase
in dose as needed for people who show a tendency
towards hypotension.
■
■
Monitor liver function before and periodically
during therapy and
arrange to discontinue the drug
at the first sign of liver toxicity.
■
■
Discontinue drug and monitor the person carefully
at any complaint of severe headache
to decrease the
risk of severe hypertension and cerebrovascular
effects.
■
■
Have phentolamine or another adrenergic blocker
on standby
as treatment in case of hypertensive
crisis.
■
■
Provide comfort measures
to help the person
tolerate drug effects.
These include voiding before
dosing, instituting a bowel program as needed,
taking food with the drug if GI upset is severe
and environmental control (lighting, temperature,
decreased stimulation).
■
■
Provide a list of potential drug–food interactions
that can cause severe toxicity
to decrease the risk
of a serious drug–food interaction.
Provide a diet
that is low in tyramine-containing foods.
■
■
Provide thorough teaching, including drug name,
prescribed dosage, measures for avoidance of
adverse effects and warning signs that may indicate
possible problems. Instruct the person about the
need for periodic monitoring and evaluation
to
enhance knowledge about drug therapy and to
promote compliance.
■
■
Offer support and encouragement
to help the
person cope with the disease and the drug regimen.
Evaluation
■
■
Monitor response to the drug (alleviation of signs
and symptoms of depression).
■
■
Monitor for adverse effects (sedation,
sympathomimetic effects, hypotension, cardiac
arrhythmias, GI disturbances, hypertensive crisis).
■
■
Evaluate the effectiveness of the teaching plan
(person can give the drug name, dosage, possible
adverse effects to watch for, specific measures to
help avoid adverse effects, importance of continued
follow-up and importance of avoiding foods high
in tyramine).
■
■
Monitor the effectiveness of comfort measures and
compliance with the regimen.
