Download Adverse Effects

Chapter 21
Cholinergic-Blocking Drugs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Cholinergic-Blocking Drugs


Drugs that block or inhibit the actions of
acetylcholine (ACh) in the parasympathetic
nervous system (PSNS)
Also known as anticholinergics,
parasympatholytics, and antimuscarinic drugs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
2
Mechanism of Action


Competitive antagonists
Compete with ACh for binding at muscarinic
receptors in the PSNS


As a result, ACh is unable to bind to the
receptor site and cause a cholinergic effect
Once these drugs bind to receptors, they inhibit
nerve transmission at these receptors
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
3
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
4
Cholinergic-Blocking Drugs:
Examples






atropine
dicyclomine (Bentyl)
glycopyrrolate (Robinul)
oxybutynin (Ditropan)
scopolamine (Transderm-Scōp)
tolterodine (Detrol)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
5
Drug Effects

Cardiovascular



Small doses: decrease heart rate
Large doses: increase heart rate
CNS


Small doses: decrease muscle rigidity
and tremors
Large doses: drowsiness, disorientation,
hallucinations
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
6
Drug Effects (cont’d)

Eye



Dilated pupils (mydriasis)
Decreased accommodation caused by paralysis
of ciliary muscles (cycloplegia)
Gastrointestinal



Relax smooth muscle tone of GI tract
Decrease intestinal and gastric secretions
Decrease motility and peristalsis
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
7
Classroom Response Question
Which finding would the nurse anticipate when
assessing a patient with an atropine overdose?
A.
B.
C.
D.
Moist skin
Miosis
Bradycardia
Urinary retention
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
8
Drug Effects (cont’d)

Genitourinary




Relaxed detrusor muscle
Increased constriction of internal sphincter
Result: urinary retention
Glandular

Decreased bronchial secretions, salivation, sweating
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
9
Drug Effects (cont’d)

Respiratory


Decreased bronchial secretions
Dilated bronchial airways
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
10
Indications: CNS

Decreasing muscle rigidity and muscle tremors


Parkinson’s disease
Drug-induced extrapyramidal reactions
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
11
Indications: Cardiovascular

Affects the heart’s conduction system


Low doses: slow the heart rate
High doses: block inhibitory vagal effects on sinoatrial
(SA) and atrioventricular (AV) node pacemaker cells
• Results in increased heart rate
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
12
Indications: Cardiovascular (cont’d)

Atropine

Used primarily for cardiovascular disorders
• Diagnosis of sinus node dysfunction
• Symptomatic second-degree heart block
• Severe sinus bradycardia with hemodynamic compromise
(advanced life support)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
13
Indications: Respiratory


Blocking the cholinergic stimulation of the PSNS
allows unopposed action of the SNS
Results




Decreased secretions from nose, mouth,
pharynx, bronchi
Relaxed smooth muscles in bronchi
and bronchioles
Decreased airway resistance
Bronchodilation
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
14
Indications: Respiratory (cont’d)

Cholinergic blockers are used to treat:

Exercise-induced bronchospasms
 Chronic bronchitis
 Asthma
 Chronic obstructive pulmonary disease
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
15
Indications: Gastrointestinal


PSNS controls gastric secretions and smooth
muscles that produce gastric motility
Blockade of PSNS results in:

Decreased secretions
 Relaxation of smooth muscle
 Decreased GI motility and peristalsis
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
16
Indications: Gastrointestinal
(cont’d)

Gastrointestinal drugs are used to treat:


Irritable bowel disease
GI hypersecretory states
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
17
Indications: Genitourinary


Reflex neurogenic bladder
Incontinence
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
18
Classroom Response Question
Glycopyrrolate (Robinul) and an opioid are
administered to a patient prior to surgery in the
preoperative area. The anticholinergic is used to
A. potentiate the action of the opioid.
B. assist the patient in retaining urine during
surgery.
C. control secretions during surgery.
D. prevent nausea.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
19
Indications


Acute pancreatitis: reduces gastric and
pancreatic secretions
Preoperatively: reduces salivary secretions
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
20
Adverse Effects
Body System
Cardiovascular
Adverse Effects
Increased heart rate,
dysrhythmias
CNS
CNS excitation,
restlessness, irritability,
disorientation,
hallucinations, delirium
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
21
Adverse Effects (cont’d)
Body System
Eye
Adverse Effects
Dilated pupils (causing
blurred vision), increased
intraocular pressure
Gastrointestinal
Decreased salivation,
decreased gastric
secretions, decreased
motility (causing
constipation)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
22
Adverse Effects (cont’d)
Body System
Genitourinary
Adverse Effects
Urinary retention
Glandular
Decreased sweating
Respiratory
Decreased bronchial
secretions
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
23
Classroom Response Question
Prior to administering tolterodine (Detrol) it is most
important for the nurse to assess the patient for a
history of which condition?
A. Angle-closure glaucoma
B. Cataracts
C. Hypothyroidism
D. Hyponatremia
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
24
Interactions


Amantadine, antihistamines, phenothiazines,
tricyclic antidepressants, digoxin
When given with other cholinergic blocking
drugs, cause additive cholinergic
effects, resulting in increased effects
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
25
Nursing Implications



Keep in mind that these drugs block the action of
ACh in the PSNS
Assess for allergies, presence of BPH, urinary
retention, glaucoma, tachycardia, MI, HF, hiatal
hernia, and GI or GU obstruction
Perform baseline assessment of vital signs and
systems overview
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
26
Nursing Implications (cont’d)



Medications should be taken exactly as
prescribed to have the maximum therapeutic
effect
Overdosing can cause life-threatening problems
Blurred vision will cause problems with driving or
operating machinery
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
27
Nursing Implications (cont’d)


Patients may experience sensitivity to light and
may want to wear dark glasses or sunglasses
When giving ophthalmic solutions, apply
pressure to the inner canthus to prevent
systemic absorption
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
28
Nursing Implications (cont’d)



Dry mouth may occur; can be handled by
chewing gum, frequent mouth care, and hard
candy
Check with physician before taking any other
medication, including over-the-counter
medications
Antidote for atropine overdose is physostigmine
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
29
Nursing Implications (cont’d)



Anticholinergics taken by the elderly patient may
lead to higher risk for heatstroke because of the
effects on heat-regulating mechanisms
Teach patients to limit physical exertion and
avoid high temperatures and strenuous exercise
Emphasize the importance of adequate fluid and
salt intake
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
30
Nursing Implications (cont’d)

Patients should report the following symptoms to
their physician: urinary hesitancy and/or
retention, constipation, tachycardia, palpitations,
tremors, confusion, sedation, hallucinations,
decreased sweating (leading to hot, dry skin)
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
31
Nursing Implications (cont’d)

Monitor for therapeutic effects



For patients with Parkinson’s disease:
fewer tremors and decreased salivation
and drooling
For patients with urologic problems: improved urinary
patterns, less hypermotility, increased time between
voiding
Monitor for adverse effects
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
32