496
P A R T 5
Drugs acting on the autonomic nervous system
Prototype summary: Donepezil
Indications:
Treatment of mild to moderate
Alzheimer’s disease.
Actions:
Reversible cholinesterase inhibitor that
causes elevated ACh levels in the cortex, which
slows the neuronal degradation of Alzheimer’s
disease.
Pharmacokinetics:
Route
Onset
Peak
Oral
Varies
2–4 hours
T
1/2
:
70 hours; metabolism is in the liver, and
excretion is in the urine.
Adverse effects:
Insomnia, fatigue, rash, nausea,
vomiting, diarrhoea, dyspepsia, abdominal pain,
muscle cramps.
Care considerations for people receiving
indirect-acting cholinergic agonists
Assessment: History and examination
■
■
Assess for contraindications or cautions:
known allergies to any of these drugs
to avoid
hypersensitivity reactions
; arrhythmias, coronary
artery disease, hypotension, urogenital or GI
obstruction or peptic ulcer,
which could be
exacerbated by cholinergic stimulation
; recent GI
or genitourinary surgery,
which could limit use of
the drugs because of the stimulatory effects of the
parasympathetic system, which could aggravate
healing
; regular use of NSAIDs, cholinergic drugs
or theophylline,
which could cause a drug–drug
interaction
; and current status of pregnancy and
breastfeeding
because of potential effects to the
fetus or neonate.
■
■
Perform a physical assessment
to establish baseline
status before beginning therapy and to determine
any potential adverse effects
: assess orientation,
affect, reflexes, ability to carry on activities of daily
living (Alzheimer’s drugs) and vision
to monitor
for CNS changes related to drug therapy
; blood
pressure, pulse, ECG, peripheral perfusion and
cardiac output
to monitor the parasympathetic
effects on the vascular system
; and urinary output
and renal and liver function tests
to monitor drug
effects on the renal system and liver, which could
change the metabolism and excretion of the drugs.
Refer to the Critical thinking scenario for a full
discussion of care for a person who is receiving
indirect-acting cholinergic agonists.
Implementation with rationale
■
■
If the drug is given intravenously, administer it
slowly
to avoid severe cholinergic effects.
■
■
Maintain atropine sulphate on standby
as an
antidote in case of overdose or severe cholinergic
reaction.
■
■
Discontinue the drug if excessive salivation,
diarrhoea, emesis or frequent urination becomes
a problem
to decrease the risk of severe adverse
reactions.
■
■
Administer the oral drug with meals
to decrease
GI upset if it is a problem.
■
■
Mark the person’s chart and notify the surgeon if
the person is to undergo surgery
because prolonged
muscle relaxation may occur if succinylcholine-
type anaesthetics are used.
The person will require
prolonged support and monitoring.
■
■
Monitor the person being treated for Alzheimer’s
disease for any progress
because the drug is not a
cure and only slows progression
; refer families to
supportive services.
■
■
The person who is being treated for myasthenia
gravis and significant others should receive
instruction in drug administration, warning signs
of drug overdose, and signs and symptoms to
report immediately
to enhance knowledge about
drug therapy and to promote compliance.
■
■
Arrange for supportive care and comfort measures,
including rest, environmental control and other
measures,
to decrease CNS irritation
; headache
medication
to relieve pain
;
safety measures if CNS
effects occur
to prevent injury
; protective measures
if CNS effects are severe
to prevent injury
; and
small, frequent meals if GI upset is severe
to
decrease discomfort and maintain nutrition.
■
■
Provide thorough teaching, including dosage,
adverse effects to anticipate and measures to avoid
them and warning signs of problems, as well as
proper administration for each route used,
to
enhance knowledge about drug therapy and to
promote compliance.
■
■
Offer support and encouragement
to help the
person deal with the drug regimen.
Evaluation
■
■
Monitor response to the drug (improvement in
condition being treated).
■
■
Monitor for adverse effects (GI upset, CNS changes,
cardiovascular changes, genitourinary changes).
■
■
Evaluate the effectiveness of the teaching plan
(person can name drug, dosage, adverse effects to
watch for and specific measures to avoid them and
proper administration).
■
■
Monitor the effectiveness of comfort measures and
compliance with the regimen.
