chapter Anticholinergic Drugs Objectives

Transcription

chapter 21
Anticholinergic Drugs
Objectives
AFTER STUDYING THIS CHAPTER, THE STUDENT WILL BE ABLE TO:
1. List characteristics of anticholinergic drugs in
terms of effects on body tissues, indications
for use, nursing process implications, observation of client response, and teaching clients.
2. Discuss atropine as the prototype of anticholinergic drugs.
3. Discuss clinical disorders/symptoms for which
anticholinergic drugs are used.
4. Describe the mechanism by which atropine
relieves bradycardia.
5. Review anticholinergic effects of antipsychotics, tricyclic antidepressants, and
antihistamines.
6. Discuss principles of therapy and nursing
process for using anticholinergic drugs in
special populations.
7. Describe the signs and symptoms of atropine or
anticholinergic drug overdose and its treatment.
8. Teach clients about the safe, effective use of
anticholinergic drugs.
Critical Thinking Scenario
George Wilson, 76 years of age, has been treated for depression with amitriptyline (Elavil) for 5 years.
He is admitted to the hospital for elective surgery, after which he becomes acutely confused. The physician
prescribes haloperidol (Haldol) PRN to control severe agitation. You note in the drug reference text that both
these medications have anticholinergic side effects.
Reflect on:
Important assessments to detect anticholinergic effects.
How anticholinergic side effects can be especially significant for the elderly.
Developing a plan to minimize or manage anticholinergic effects for this client.
DESCRIPTION
Anticholinergic drugs, also called cholinergic blocking and
parasympatholytic agents, block the action of acetylcholine on
the parasympathetic nervous system (PNS). Most anticholinergic drugs interact with muscarinic cholinergic receptors in
the brain, secretory glands, heart, and smooth muscle and are
also called antimuscarinic agents. A few anticholinergic drugs,
when given at high doses, are also able to block nicotinic receptors in autonomic ganglia and skeletal muscles. Glycopyrrolate (Robinul) is an example of such a medication. The
prototype anticholinergic drug is atropine, and this drug class
includes belladonna alkaloids, their derivatives, and many synthetic substitutes.
Most anticholinergic medications are either tertiary
amines or quaternary amines in their chemical structure. Tertiary amines are uncharged lipid-soluble molecules. Atropine
and scopolamine are tertiary amines and therefore are able to
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cross cell membranes readily. They are well absorbed from
the gastrointestinal (GI) tract and conjunctiva and they cross
the blood–brain barrier. Tertiary amines are excreted in the
urine. Some belladonna derivatives and synthetic anticholinergics are quaternary amines. These drugs carry a positive
charge and are lipid insoluble. Consequently, they do not readily cross cell membranes. They are poorly absorbed from the GI
tract and do not cross the blood–brain barrier. Quaternary
amines are excreted largely in the feces. Table 21–1 lists common tertiary amine and quaternary amine anticholinergic drugs.
Mechanism of Action and Effects
These drugs act by occupying receptor sites at parasympathetic nerve endings, thereby leaving fewer receptor sites free
to respond to acetylcholine (Fig. 21–1). Parasympathetic response is absent or decreased, depending on the number of
CHAPTER 21 ANTICHOLINERGIC DRUGS
TABLE 21–1
Common Tertiary Amine
and Quaternary Amine
Tertiary Amines
Quarternary Amines
Atropine
Benztropine (Cogentin)
Biperiden (Akineton)
Dicyclomine hydrochloride (Bentyl)
Flavoxate (Urispas)
l-Hyoscyamine (Anaspaz)
Oxybutynin (Ditropan)
Procyclidine (Kemadrin)
Scopolamine
Tolterodine (Detrol and Detrol LA)
Trihexyphenidyl (Trihexy)
Glycopyrrolate (Robinul)
Ipratropium (Atrovent)
Mepenzolate (Cantil)
Methscopolamine (Pamine)
Propantheline bromide
(Pro-Banthine)
receptors blocked by anticholinergic drugs and the underlying degree of parasympathetic activity. Since cholinergic
muscarinic receptors are widely distributed in the body, anticholinergic drugs produce effects in a variety of locations, including the central nervous system, heart, smooth muscle,
glands, and the eye.
Specific effects on body tissues and organs include:
1. Central nervous system (CNS) stimulation followed
by depression, which may result in coma and death.
This is most likely to occur with large doses of anticholinergic drugs that cross the blood–brain barrier
(atropine, scopolamine, and antiparkinson agents).
2. Decreased cardiovascular response to parasympathetic (vagal) stimulation that slows heart rate. Atropine is the anticholinergic drug most often used for its
cardiovascular effects. According to Advanced Cardiac
Life Support (ACLS) protocol (2000), atropine is the
Nerve ending
Presynaptic vesicles
containing acetylcholine
Acetylcholine
Anticholinergic
drug
Muscarinic
receptor
Effector target organ
Figure 21–1 Mechanism of action of anticholinergic drugs. Anticholinergic (antimuscarinic) blocking agents prevent acetylcholine from
interacting with muscarinic receptors on target effector organs, thus
blocking or decreasing a parasympathetic response in these organs.
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drug of choice to treat symptomatic sinus bradycardia.
Low doses (<0.5 mg) may produce a slight and temporary decrease in heart rate; however, moderate to large
doses (0.5 to 1 mg) increase heart rate by blocking
parasympathetic vagal stimulation. Although the increase in heart rate may be therapeutic in bradycardia, it
can be an adverse effect in patients with other types of
heart disease because atropine increases the myocardial
oxygen demand. Atropine usually has little or no effect
on blood pressure. Large doses cause facial flushing because of dilation of blood vessels in the neck.
3. Bronchodilation and decreased respiratory tract secretions. Bronchodilating effects result from blocking
the bronchoconstrictive effects of acetylcholine. When
anticholinergic drugs are given systemically, respiratory
secretions decrease and may become viscous, resulting
in mucous plugging of small respiratory passages. Administering the medications by inhalation decreases this
effect while preserving the beneficial bronchodilation
effect.
4. Antispasmodic effects in the GI tract due to decreased muscle tone and motility. The drugs have
little inhibitory effect on gastric acid secretion with
usual doses and insignificant effects on pancreatic and
intestinal secretions.
5. Mydriasis and cycloplegia in the eye. Normally, anticholinergics do not change intraocular pressure, but
with narrow-angle glaucoma, they may increase intraocular pressure and precipitate an episode of acute
glaucoma. When the pupil is fully dilated, photophobia
may be bothersome, and reflexes to light and accommodation may disappear.
6. Miscellaneous effects include decreased secretions
from salivary and sweat glands; relaxation of ureters,
urinary bladder, and the detrusor muscle; and relaxation
of smooth muscle in the gallbladder and bile ducts.
The clinical usefulness of anticholinergic drugs is limited
by their widespread effects. Consequently, several synthetic
drugs have been developed in an effort to increase selectivity
of action on particular body tissues, especially to retain the
antispasmodic and antisecretory effects of atropine while
eliminating its adverse effects. This effort has been less than
successful—all the synthetic drugs produce atropine-like adverse effects when given in sufficient dosage.
One group of synthetic drugs is used for antispasmodic
effects in GI disorders. Another group of synthetic drugs includes centrally active anticholinergics used in the treatment
of Parkinson’s disease (see Chap. 12). They balance the relative cholinergic dominance that causes the movement disorders associated with parkinsonism.
Indications for Use
Anticholinergic drugs are used for disorders in many body
systems. Clinical indications for use of anticholinergic drugs
include GI, genitourinary, ophthalmic and respiratory dis-
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SECTION 3 DRUGS AFFECTING THE AUTONOMIC NERVOUS SYSTEM
orders, bradycardia, and Parkinson’s disease. They also are
used before surgery and bronchoscopy. Drugs at a Glance:
Selected Anticholinergic Drugs describes the therapeutic use,
dosage and route of administration of selected anticholinergic medications.
• GI disorders in which anticholinergics have been used
include peptic ulcer disease, gastritis, pylorospasm, diverticulitis, ileitis, and ulcerative colitis. These conditions are often characterized by excessive gastric acid
and abdominal pain because of increased motility and
spasm of GI smooth muscle. In peptic ulcer disease,
more effective drugs have been developed, and anticholinergics are rarely used. The drugs are weak inhibitors
of gastric acid secretion even in maximal doses (which
usually produce intolerable adverse effects). Although
they do not heal peptic ulcers, they may relieve abdominal pain by relaxing GI smooth muscle.
Anticholinergics may be helpful in treating irritable
colon or colitis, but they may be contraindicated in
chronic inflammatory disorders (eg, diverticulitis, ulcerative colitis) or acute intestinal infections (eg, bacterial,
viral, amebic). Other drugs are used to decrease diarrhea
and intestinal motility in these conditions.
• In genitourinary disorders, anticholinergic drugs may
be given for their antispasmodic effects on smooth muscle to relieve the symptoms of urinary incontinence and
frequency that accompany an overactive bladder. In
infections such as cystitis, urethritis, and prostatitis, the
drugs decrease the frequency and pain of urination. The
drugs are also given to increase bladder capacity in
enuresis, paraplegia, or neurogenic bladder.
• In ophthalmology, anticholinergic drugs are applied
topically for mydriatic and cycloplegic effects to aid
examination or surgery. They are also used to treat
some inflammatory disorders. Anticholinergic preparations used in ophthalmology are discussed further in
Chapter 65.
• In respiratory disorders characterized by bronchoconstriction (ie, asthma, chronic bronchitis), ipratropium
(Atrovent) may be given by inhalation for bronchodilating effects (see Chap. 47).
• In cardiology, atropine may be given to increase heart
rate in bradycardia and heart block characterized by
hypotension and shock.
• In Parkinson’s disease, anticholinergic drugs are given
for their central effects in decreasing salivation, spasticity, and tremors. They are used mainly in clients who
have minimal symptoms, who do not respond to levodopa, or who cannot tolerate levodopa because of adverse reactions or contraindications. An additional use
of anticholinergic drugs is to relieve Parkinson-like
symptoms that occur with older antipsychotic drugs.
• Before surgery, anticholinergics are given to prevent
vagal stimulation and potential bradycardia, hypotension, and cardiac arrest. They are also given to reduce
respiratory tract secretions, especially in head and neck
surgery and bronchoscopy.
Contraindications to Use
Contraindications to the use of anticholinergic drugs include
any condition characterized by symptoms that would be aggravated by the drugs. Some of these are prostatic hypertrophy,
myasthenia gravis, hyperthyroidism, glaucoma, tachyarrhythmias, myocardial infarction, and heart failure unless bradycardia is present. They should not be given in hiatal hernia or other
conditions contributing to reflux esophagitis because the drugs
delay gastric emptying, relax the cardioesophageal sphincter,
and increase esophageal reflux.
INDIVIDUAL
ANTICHOLINERGIC DRUGS
Belladonna Alkaloids and Derivatives
Atropine, the prototype of anticholinergic drugs, produces
the same effects, has the same clinical indications for use, and
has the same contraindications as those described earlier. In
addition, it is used as an antidote for an overdose of cholinergic drugs and exposure to insecticides that have cholinergic
effects.
Atropine is a naturally occurring belladonna alkaloid that
can be extracted from the belladonna plant or prepared synthetically. It is usually prepared as atropine sulfate, a salt that
is very soluble in water. It is well absorbed from the GI tract
and distributed throughout the body. It crosses the blood–brain
barrier to enter the CNS, where large doses produce stimulant
effects and toxic doses produce depressant effects. Atropine is
also absorbed systemically when applied locally to mucous
membranes. The drug is rapidly excreted in the urine. Pharmacologic effects are of short duration except for ocular
effects, which may last for several days.
Belladonna tincture is a mixture of alkaloids in an aqueousalcohol solution. It is most often used in GI disorders for antispasmodic effect. It is an ingredient in several drug mixtures.
Homatropine hydrobromide (Homapin) is a semisynthetic derivative of atropine used as eye drops to produce mydriasis and cycloplegia. Homatropine may be preferable to
atropine because ocular effects do not last as long.
Hyoscyamine (Anaspaz) is a belladonna alkaloid used
in GI and genitourinary disorders characterized by spasm,
increased secretion, and increased motility. It has the same
effects as other atropine-like drugs.
Ipratropium (Atrovent) is an anticholinergic drug chemically related to atropine. When given as a nasal spray, it is useful in treating rhinorrhea due to allergy or the common cold.
When given as an inhalation treatment or aerosol to patients
with chronic obstructive pulmonary disease (COPD), it is beneficial as a bronchodilator. An advantage of administration of
anticholinergic drugs by the respiratory route over systemic administration is less thickening of respiratory secretions and reduced incidence of mucus-plugged airways.
Scopolamine is similar to atropine in uses, adverse
effects, and peripheral effects but different in central effects.
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Drugs at a Glance: Selected Anticholinergic Drugs
Routes and Dosage Ranges
Generic/Trade Name
Use
Adults
Children
Belladonna Alkaloids and Derivatives
Atropine
Systemic use
PO, IM, SC, IV 0.4–0.6 mg
Surgery
IM, SC, or IV 0.4–0.6 mg prior
to induction. Use 0.4-mg
dose with cyclopropane
anesthesia.
IV 0.4–1 mg (up to 2 mg)
q1–2h PRN.
IV titrate large doses of 2–3 mg
as needed until signs of
atropine toxicity appear and
cholinergic crisis is controlled.
For refraction: Instill 1–2 drops
of 1% solution into eye(s) 1 h
before refraction.
For uveitis: Instill 1–2 drops of
1% solution into eye(s) qid.
of 2% solution or 1 drop
5% solution into eye before
procedure. May repeat at
5–10 min intervals as
needed.
For uveitis: Instill 1–2 drops of
2% or 5% solution bid to tid
or every 3–4 h as needed.
PO, SL 0.125–0.25 mg tid or
qid, ac and hs. PO (timedrelease formula):
0.375–0.75 q12h. IM, IV,
SC: 0.25–0.5 mg q6h.
2 puffs (36 mcg) of aerosol qid.
Additional inhalations may
be needed. Do not exceed
12 puffs/24h. Solution for
inhalation: 500 mcg, tid–qid.
2 sprays/nostril of 0.03% spray
bid–tid.
tid–qid.
PO 0.4–0.8 mg qd.
SC, IM 0.32–0.65 mg
IV 0.32–0.65 mg diluted in
sterile water for injection.
Transdermal: Apply disc 4 h
before antiemetic effect is
needed. Replace q 3 days.
into eye 1 h before refracting.
For uveitis: Instill 1–2 drops
into eye(s) up to tid.
PO, IM, SC, IV:
7–16 lbs: 0.1 mg
16–24 lbs: 0.15 mg
24–40 lbs: 0.2 mg
40–65 lbs: 0.3 mg
65–90 lbs: 0.4 mg
>90 lbs 0.4–0.6 mg
0.1 mg (newborn) to 0.6 mg
(12 y) given SC 30 min prior
to surgery.
Bradyarrythmias
Antidote for cholinergic poisoning
Ophthalmic atropine (Isopto-Atropine)
Mydriatic/cycloplegia/
inflammation of uveal tract
Homatropine (Homapin)
Hyoscyamine (Anaspaz)
Antispasmodic Antisecretory
for gastrointestinal (GI) and
genitourinary (GU) disorders
Ipratropium (Atrovent)
Bronchodilation
Nasal spray for rhinorrhea
Scopolamine
Systemic use
Antiemetic
of 0.5% solution bid for
1–3 days before procedure.
For refraction: Instill 1 drop of
2% solution into eye before
procedure. May repeat q 10
min as needed. For uveitis:
Instill 1 drop of 2% solution
bid to tid.
Children 2–10 y: PO
0.062–0.125 mg q 6–8h.
Children <2 y: half of the
previous dose.
bid–tid.
Not approved for PO use <6 y.
Parenteral: 0.006 mg/kg.
Maximum dose: 0.3 mg.
Not approved in children.
Same as adult dose
(continued )
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Drugs at a Glance: Selected Anticholinergic Drugs (continued )
Routes and Dosage Ranges
Generic/Trade Name
Use
Antisecretory/Antispasmodic Anticholinergics for GI Disorders
Dicyclomine hydrochloride (Bentyl)
Antisecretory/antispasmodic
Glycopyrrolate (Robinul)
Preanesthetic
Mepenzolate (Cantil)
Methscopolamine (Pamine)
Propantheline bromide (Pro-Banthine)
Anticholinergics Used in Parkinson’s Disease
Benztropine (Cogentin)
Parkinsonism
Drug-induced extrapyramidal
symptoms
Biperiden (Akineton)
Parkinsonism
symptoms
Procyclidine (Kemadrin)
Parkinsonism
symptoms
Trihexyphenidyl (Trihexy)
Parkinsonism
symptoms
Urinary Antispasmodics
Flavoxate (Urispas)
Oxybutynin (Ditropan and Ditropan XL)
Tolterodine (Detrol and Detrol LA)
ac, before meals; hs, bedtime; pc, after meals.
Adults
PO 20–40 mg ac & hs
IM 20 mg ac & hs
PO 1–2 mg bid–tid
IM, IV 0.1–0.2 mg
IM 0.004 mg/kg 30–60 min
before anesthesia
PO 25–50 mg qid ac & hs
PO 2.5–5 mg 30 min ac & hs
PO 7.5–15 mg 30 min ac & hs
Children
< 12 y: not recommended
<2 y: 0.004 mg/lb IM
30–60 min before
anesthesia.
2–12 y: 0.002–0.004 mg/lb
IM 30–60 min before
anesthesia.
200 mcg/kg ac & hs
PO, IM, IV 0.5–1 mg hs. May
increase up to 6 mg given hs
or in 2–4 divided doses.
For acute dystonia: IM, IV 1–2
mg. May repeat if needed.
For prevention: PO 1–2 mg.
PO 2 mg tid–qid. Maximum
dose 16 mg/day.
PO 2 mg tid–qid
IM, IV 2 mg. Repeat q12h
until symptoms are resolved.
Do not give more than
4 doses/24h
PO 2.5 mg tid pc. May increase
to 5 mg tid.
PO 2.5 mg tid. Increase by
2.5-mg increments until symptoms are resolved. Usual
maximum dose 10–20 mg/d.
PO 1–2 mg. Increase by 2 mg
increments at 3–5-d intervals
until a total of 6–10 mg is
given qd in divided doses
3–4 times/d at mealtimes
and bedtimes.
PO 1 mg initially. Increase as
needed to control symptoms.
PO 100–200 mg tid–qid.
Reduce when symptoms
improve.
PO 5 mg bid or tid.
Maximum dose 5 mg qid.
Extended-release 5 mg PO qd
up to 30 mg/d.
PO 2 mg bid. May decrease to
1 mg when symptoms improve. Reduce doses to
1 mg PO bid in presence of
hepatic impairment.
<12 y: safety and efficacy not
established
>5 y: 5 mg PO bid. Maximum
dose 5 mg tid.
Safety and efficacy not
established.
When given parenterally, scopolamine depresses the CNS
and causes amnesia, drowsiness, euphoria, relaxation, and
sleep. Effects of scopolamine appear more quickly and disappear more readily than those of atropine. Scopolamine
also is used in motion sickness. It is available as oral tablets
and as a transdermal adhesive disc that is placed behind the
ear. The disc (Transderm-V) protects against motion sickness for 72 hours.
Centrally Acting Anticholinergics
Used in Parkinson’s Disease
Older anticholinergic drugs such as atropine are rarely used to
treat Parkinson’s disease because of their undesirable peripheral effects (eg, dry mouth, blurred vision, photophobia, constipation, urinary retention, and tachycardia). Newer, centrally
acting synthetic anticholinergic drugs are more selective for
muscarinic receptors in the CNS and are designed to produce
fewer side effects.
Trihexyphenidyl (Trihexy) is used in the treatment of
parkinsonism and extrapyramidal reactions caused by some
antipsychotic drugs. Trihexyphenidyl relieves smooth muscle spasm by a direct action on the muscle and by inhibiting
the PNS. The drug supposedly has fewer side effects than atropine, but approximately half the recipients report mouth
dryness, blurring of vision, and other side effects common to
anticholinergic drugs. Trihexyphenidyl requires the same
precautions as other anticholinergic drugs and is contraindicated in glaucoma. Biperiden (Akineton) and procyclidine
(Kemadrin) are chemical derivatives of trihexyphenidyl and
have similar actions.
Benztropine (Cogentin) is a synthetic drug with both anticholinergic and antihistaminic effects. Its anticholinergic
activity approximates that of atropine. A major clinical use is
to treat acute dystonic reactions caused by antipsychotic
drugs and to prevent their recurrence in clients receiving
long-term antipsychotic drug therapy. It also may be given in
small doses to supplement other antiparkinson drugs. In full
dosage, adverse reactions are common.
Urinary Antispasmodics
Flavoxate (Urispas) was developed specifically to counteract spasm in smooth muscle tissue of the urinary tract. It has
anticholinergic, local anesthetic, and analgesic effects. Thus,
the drug relieves dysuria, urgency, frequency, and pain with
genitourinary infections, such as cystitis and prostatitis.
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How Can You Avoid This Medication Error?
Sam Miller is admitted for elective surgery. He has a history of
heart disease, glaucoma, and benign prostatic hyperplasia (BPH).
After surgery, a scopolamine patch is prescribed to control nausea.
You administer the patch, as ordered, placing it on his chest in a
nonhairy area.
Oxybutynin (Ditropan and Ditropan XL) has direct antispasmodic effects on smooth muscle and anticholinergic effects. It increases bladder capacity and decreases frequency
of voiding in clients with neurogenic bladder. Oxybutynin is
now available in an extended-release form for once a day
dosing.
Tolterodine (Detrol and Detrol LA) is a competitive antimuscarinic, anticholinergic agent that inhibits bladder contraction, decreases detrusor muscle pressure, and delays the
urge to void. It is used to treat urinary frequency, urgency, and
urge incontinence. Tolterodine is more selective for muscarinic
receptors in the urinary bladder than other areas of the body,
such as the salivary glands, and therefore anticholinergic side
effects are less marked. Reduced doses (of 1 mg) are recommended for those with hepatic dysfunction. Tolterodine is also
available in an extended-release form.
Nursing Process
Assessment
• Assess the client’s condition in relation to disorders for
which anticholinergic drugs are used (ie, check for bradycardia or heart block, diarrhea, dysuria, abdominal pain,
and other disorders). If the client reports or medical records
indicate a specific disorder, assess for signs and symptoms
of that disorder (eg, Parkinson’s disease).
• Assess for disorders in which anticholinergic drugs are
contraindicated (eg, glaucoma, prostatic hypertrophy, reflux esophagitis, myasthenia gravis, hyperthyroidism).
• Assess use of other drugs with anticholinergic effects,
such as antihistamines (histamine-1 receptor antagonists
[see Chap. 48]), antipsychotic agents, and tricyclic antidepressants.
Nursing Diagnoses
• Impaired Urinary Elimination: Decreased bladder tone
and urine retention
Nursing Notes: Apply Your Knowledge
Scott Andrews is scheduled for a bronchoscopy. Before this
procedure, you have been ordered to give him Valium and atropine. Explain the rationale of giving an anticholinergic agent
as a preoperative medication.
• Constipation related to slowed GI function
• Disturbed Thought Processes: Confusion, disorientation,
especially in older adults
• Deficient Knowledge: Drug effects and accurate usage
• Risk for Injury related to drug-induced blurred vision and
photophobia
• Risk for Noncompliance related to adverse drug effects
• Risk for Altered Body Temperature: Hyperthermia
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Planning/Goals
The client will:
• Receive or self-administer the drugs correctly
• Experience relief of symptoms for which anticholinergic
drugs are given
• Be assisted to avoid or cope with adverse drug effects on
vision, thought processes, bowel and bladder elimination,
and heat dissipation
Interventions
Use measures to decrease the need for anticholinergic drugs.
For example, with peptic ulcer disease, teach the client to
avoid factors known to increase gastric secretion and GI
motility (alcohol; cigarette smoking; caffeine-containing
beverages, such as coffee, tea, and cola drinks; ulcerogenic
drugs, such as aspirin). Late evening snacks also should be
avoided because increased gastric acid secretion occurs approximately 90 minutes after eating and may cause pain and
awakening from sleep. Although milk was once considered
an “ulcer food,” it contains protein and calcium, which promote acid secretion, and is a poor buffer of gastric acid. Thus,
drinking large amounts of milk should be avoided.
Evaluation
• Interview and observe in relation to safe, accurate drug
administration.
• Interview and observe for relief of symptoms for which
the drugs are given.
• Interview and observe for adverse drug effects.
PRINCIPLES OF THERAPY
Gastrointestinal Disorders
When anticholinergic drugs are given for GI disorders, larger
doses may be given at bedtime to prevent pain and awakening during sleep.
Parkinsonism
When these drugs are used in parkinsonism, small doses are
given initially and gradually increased. This regimen decreases
adverse reactions.
Extrapyramidal Reactions
When used in drug-induced extrapyramidal reactions
(parkinson-like symptoms), these drugs should be prescribed
only if symptoms occur. They should not be used routinely to
prevent extrapyramidal reactions because fewer than half the
clients taking antipsychotic drugs experience such reactions.
Most drug-induced reactions last approximately 3 months and
do not recur if anticholinergic drugs are discontinued at that
time. (An exception is tardive dyskinesia, which does not respond to anticholinergic drugs and may be aggravated by them.)
Muscarinic Agonist Poisoning
Atropine is the antidote for poisoning by muscarinic agonists such as certain species of mushrooms, cholinergic agonist drugs, cholinesterase inhibitor drugs, and insecticides
containing organophosphates. Symptoms of muscarinic poisoning include salivation, lacrimation, visual disturbances,
bronchospasm, diarrhea, bradycardia, and hypotension.
Atropine blocks the poison from interacting with the muscarinic receptor, thus reversing the toxic effects.
Use in Specific Conditions
Asthma
Renal or Biliary Colic
Atropine is sometimes given with morphine or meperidine to
relieve the severe pain of renal or biliary colic. It acts mainly
to decrease the spasm-producing effects of the opioid analgesics. It has little antispasmodic effect on the involved muscles and is not used alone for this purpose.
Oral anticholinergics are not used to treat asthma and other
chronic obstructive pulmonary diseases because of their tendency to thicken secretions and form mucus plugs in airways.
Ipratropium (Atrovent) may be given by inhalation to produce
bronchodilation without thickening of respiratory secretions.
Preoperative Use in Clients With Glaucoma
Toxicity of Anticholinergics:
Recognition and Management
Glaucoma is usually listed as a contraindication to anticholinergic drugs because the drugs impair outflow of aqueous humor
and may cause an acute attack of glaucoma (increased intraocular pressure). However, anticholinergic drugs can be given
safely before surgery to clients with open-angle glaucoma
(80% of clients with primary glaucoma) if they are receiving
miotic drugs, such as pilocarpine. If anticholinergic preoperative medication is needed in clients predisposed to angle
closure, the hazard of causing acute glaucoma can be minimized by also giving pilocarpine eye drops and acetazolamide
(Diamox).
Overdosage of atropine or other anticholinergic drugs produces the usual pharmacologic effects in a severe and exaggerated form. The anticholinergic overdose syndrome is
characterized by hyperthermia; hot, dry, flushed skin; dry
mouth; mydriasis; delirium; tachycardia; ileus; and urinary retention. Myoclonic movements and choreoathetosis may be
seen. Seizures, coma, and respiratory arrest may also occur.
Treatment involves use of activated charcoal to absorb ingested
poison. Hemodialysis, hemoperfusion, peritoneal dialysis, and
repeated doses of charcoal are not effective in removing anticholinergic agents.
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CLIENT TEACHING GUIDELINES
General Considerations
✔ Do not take other drugs without the physician’s knowledge. In addition to some prescribed antiparkinson drugs,
antidepressants, antihistamines, and antipsychotic drugs
with anticholinergic properties, over-the-counter sleeping
pills and antihistamines have anticholinergic effects. Taking any of these concurrently could cause overdosage or
excessive anticholinergic effects.
✔ Use measures to minimize risks of heat exhaustion and
heat stroke:
✔ Wear light, cool clothing in warm climates or environments.
✔ Maintain fluid and salt intake if not contraindicated.
✔ Limit exposure to direct sunlight.
✔ Limit physical activity.
✔ Take frequent cool baths.
✔ Ensure adequate ventilation, with fans or air conditioners if necessary.
✔ Avoid alcoholic beverages.
✔ Use sugarless chewing gum and hard candy, if not contraindicated, to relieve mouth dryness.
✔ Carry out good dental hygiene practices (eg, regular
brushing of teeth) to prevent dental caries and loss of
teeth that may result from drug-induced xerostomia (dry
mouth from decreased saliva production). This is more
likely to occur with long-term use of these drugs.
Physostigmine salicylate (Antilirium), an acetylcholinesterase inhibitor, is a specific antidote. It is usually given intravenously (IV) at a slow rate of injection. Adult dosage is 2 mg
(no more than 1 mg/minute); child dosage is 0.5 to 1 mg
(no more than 0.5 mg/minute). Rapid administration may
cause bradycardia, hypersalivation (with subsequent respiratory distress), and seizures. Repeated doses may be given if
life-threatening dysrhythmias, convulsions, or coma occur.
Diazepam (Valium) or a similar drug may be given for excessive CNS stimulation (delirium, excitement). Ice bags,
cooling blankets, and tepid sponge baths may help reduce
fever. Artificial ventilation and cardiopulmonary resuscitative measures are used if excessive depression of the CNS
causes coma and respiratory failure. Infants, children, and the
elderly are especially susceptible to the toxic effects of anticholinergic agents.
✔ To prevent injury due to blurring of vision or drowsiness,
avoid potentially hazardous activities (eg, driving or operating machinery).
✔ To reduce sensitivity to light (photophobia), dark glasses
can be worn outdoors in strong light.
✔ Contact lens wearers who experience dry eyes may need
to use an ophthalmic lubricating solution.
✔ When using anticholinergic ophthalmic preparations, if
eye pain occurs, stop using the medication and contact
your physician or health care provider. This may be a
warning sign of undiagnosed glaucoma.
✔ Notify your physician or health care provider if urinary retention or constipation occurs.
✔ Tell your physician or health care provider if you are pregnant or breast-feeding or allergic to sulfite preservatives
or any other atropine compound.
Self-Administration
✔ Take anticholinergic drugs for gastrointestinal disorders
30 minutes before meals and at bedtime.
✔ Safeguard anticholinergic medications from children because they are especially sensitive to atropine poisoning.
✔ To prevent constipation, use a diet high in fiber. Include
whole grains, fruits, and vegetables in your daily menu.
Also, drink 2 to 3 quarts of fluid a day and exercise
regularly.
spasmodics, flavoxate is not recommended for children
younger than 12 years, oxybutynin is not recommended for
children younger than 5 years of age, and the safety and efficacy of tolterodine are not established in children.
The drugs cause the same adverse effects in children as in
adults. However, they may be more severe because children
are especially sensitive to the drugs. Facial flushing is common in children, and a skin rash may occur.
Ophthalmic anticholinergic drugs are used for cycloplegia
and mydriasis before eye examinations and surgical procedures (see Chap. 65). They should be used only with close
medical supervision. Cyclopentolate (Cyclogyl) and tropicamide (Mydriacyl) have been associated with behavioral disturbances and psychotic reactions in children. Tropicamide
also has been associated with cardiopulmonary collapse.
Use in Older Adults
Use in Children
Systemic anticholinergics, including atropine, glycopyrrolate
(Robinul), and scopolamine, are given to children of all ages
for essentially the same effects as for adults. Most of the antisecretory, antispasmodic agents for gastrointestinal disorders
are not recommended for children. With the urinary anti-
Anticholinergic drugs are given for the same purposes as in
younger adults. In addition to the primary anticholinergic
drugs, many others that are commonly prescribed for older
adults have high anticholinergic activity. These include many
antihistamines (histamine-1 receptor antagonists), tricyclic
antidepressants, and antipsychotic drugs.
316
Older adults are especially likely to have significant adverse reactions because of slowed drug metabolism and the
frequent presence of several disease processes. Some common adverse effects and suggestions for reducing their impact are:
• Blurred vision. The client may need help with ambulation, especially with stairs or other potentially hazardous environments. Remove obstacles and hazards
when possible.
• Confusion. Provide whatever assistance is needed to
prevent falls and other injuries.
• Heat stroke. Help to avoid precipitating factors, such as
strenuous activity and high environmental temperatures.
• Constipation. Encourage or assist with an adequate intake of high-fiber foods and fluids and adequate exercise
when feasible.
• Urinary retention. Encourage adequate fluid intake
and avoid high doses of the drugs. Men should be examined for prostatic hypertrophy.
• Hallucinations and other psychotic symptoms.
These are most likely to occur with the centrally active
anticholinergics given for Parkinson’s disease or druginduced extrapyramidal effects, such as trihexyphenidyl
or benztropine. Dosage of these drugs should be carefully
regulated and supervised.
such a medication. In the presence of liver impairment,
dosages should be reduced and given less frequently.
Use in Critical Illness
Atropine is an important drug in the emergency drug box. According to ACLS guidelines, atropine is the first drug to be administered in the emergency treatment of bradyarrhythmias.
Atropine 0.5 to 1 mg should be administered IV every 5 minutes and may be repeated up to 2 to 3 mg (0.03 to 0.04 mg/kg
total dose). For clients with asystole, 1 mg of atropine is administered IV and repeated every 3 to 5 minutes if asystole
persists, up to 0.04 mg/kg. Administration of atropine in doses
less than 0.5 mg should be avoided because this may result in
a paradoxical bradycardia. Atropine may be administered by
endotracheal tube in clients without an intravenous access.
The recommended dose is 2 to 3 mg diluted in 10 mL normal
saline.
Abuse of Anticholinergic Agents
Anticholinergic drugs have potential intoxicating effects.
Abuse of these drugs may produce euphoria, disorientation,
hallucinations, and paranoia in addition to the classic anticholinergic adverse reactions.
Use in Renal Impairment
Anticholinergic agents that have a tertiary amine structure,
such as atropine, are eliminated by a combination of hepatic
metabolism and renal excretion. In the presence of renal impairment, they may accumulate and cause increased adverse
effects. Quaternary amines are eliminated largely in the feces
and are less affected by renal impairment.
Use in Hepatic Impairment
Because some anticholinergic drugs are metabolized by the
liver, they may accumulate and cause adverse effects in the
presence of hepatic impairment. Tolterodine is an example of
Home Care
Anticholinergic medications are commonly used in home
care with children and adults. Children and older adults are
probably most likely to experience adverse effects of these
drugs and should be monitored carefully. With elderly clients,
the home care nurse needs to assess medication regimens for
combinations of drugs with anticholinergic effects, especially if mental confusion develops or worsens. The home
care nurse may also need to teach elderly clients or caregivers that the drugs prevent sweating and heat loss and increase risks of heat stroke if precautions to avoid overheating
are not taken.
NURSING
ACTIONS
317
NURSING ACTIONS
RATIONALE/EXPLANATION
1. Administer accurately
a. For gastrointestinal disorders, give most oral anticholinergic drugs approximately 30 min before meals and at bedtime.
To allow the drugs to reach peak antisecretory effects by the time
ingested food is stimulating gastric acid secretion. Bedtime administration helps prevent awakening with abdominal pain.
b. When given before surgery, parenteral preparations of atropine can be mixed in the same syringe with several other
common preoperative medications, such as meperidine (Demerol), morphine, oxymorphone (Numorphan), and promethazine (Phenergan).
The primary reason for mixing medications in the same syringe is
to decrease the number of injections and thus decrease client discomfort. Note, however, that extra caution is required when mixing
drugs to be sure that the dosage of each drug is accurate. Also, if any
question exists regarding compatibility with another drug, it is safer
not to mix the drugs, even if two or three injections are required.
c. When applying topical atropine solutions or ointment to the
eye, be sure to use the correct concentration and blot any excess from the inner canthus.
Atropine ophthalmic preparations are available in several concentrations (usually 1%, 2%, and 3%). Excess medication should be
removed so the drug will not enter the nasolacrimal (tear) ducts
and be absorbed systemically through the mucous membrane of
the nasopharynx or be carried to the throat and swallowed.
d. If propantheline is to be given intravenously, dissolve the
30-mg dose of powder in no less than 10 mL of sterile water
for injection.
Parenteral administration is reserved for clients who cannot take
the drug orally.
e. Instruct clients to swallow oral propantheline tablets, not to
chew them.
The tablets have a hard sugar coating to mask the bitter taste of
the drug.
f. Parenteral glycopyrrolate can be given through the tubing
of a running intravenous infusion of physiologic saline or lactated Ringer’s solution.
g. Do not crush extended-release forms of anticholinergic drugs
such as Detrol LA and Ditropan XL.
2. Observe for therapeutic effects
Crushing long-acting medications may result in high blood levels
of the medication and increased adverse effects.
Therapeutic effects depend primarily on the reason for use. Thus,
a therapeutic effect in one condition may be a side effect or an adverse reaction in another condition.
a. When a drug is given for peptic ulcer disease or other gastrointestinal disorders, observe for decreased abdominal pain.
Relief of abdominal pain is due to the smooth muscle relaxant or
antispasmodic effect of the drug.
b. When the drug is given for diagnosing or treating eye disorders, observe for pupil dilation (mydriasis) and blurring of
vision (cycloplegia).
Note that these ocular effects are side effects when the drugs are
given for problems not related to the eyes.
c. When the drug is given for symptomatic bradycardia, observe
for increased pulse rate.
These drugs increase heart rate by blocking action of the vagus
nerve.
d. When the drug is given for urinary tract disorders, such
as cystitis or enuresis, observe for decreased frequency of urination. When the drug is given for renal colic due to stones,
observe for decreased pain.
Anticholinergic drugs decrease muscle tone and spasm in the
smooth muscle of the ureters and urinary bladder.
e. When the centrally acting anticholinergics are given for
Parkinson’s disease, observe for decrease in tremor, salivation,
and drooling.
Decreased salivation is a therapeutic effect with parkinsonism but
an adverse reaction in most other conditions.
(continued )
318
NURSING ACTIONS
RATIONALE/EXPLANATION
3. Observe for adverse effects
These depend on reasons for use and are dose related.
a. Tachycardia
Tachycardia may occur with usual therapeutic doses because anticholinergic drugs block vagal action, which normally slows heart
rate. Tachycardia is not likely to be serious except in clients with
underlying heart disease. For example, in clients with angina pectoris, prolonged or severe tachycardia may increase myocardial
ischemia to the point of causing an acute attack of angina (chest pain)
or even myocardial infarction. In clients with congestive heart failure, severe or prolonged tachycardia can increase the workload of the
heart to the point of causing acute heart failure or pulmonary edema.
b. Excessive central nervous system (CNS) stimulation (tremor,
restlessness, confusion, hallucinations, delirium) followed by
excessive CNS depression (coma, respiratory depression)
These effects are more likely to occur with large doses of atropine
because atropine crosses the blood-brain barrier. Large doses of
trihexyphenidyl (Trihexy) also may cause CNS stimulation.
c. Sedation and amnesia with scopolamine or benztropine
(Cogentin)
This may be a therapeutic effect but becomes an adverse reaction if
severe or if the drug is given for another purpose. Benztropine has
anticholinergic and antihistaminic properties. Apparently, drowsiness and sedation are caused by the antihistaminic component.
d. Constipation or paralytic ileus
These effects are the result of decreased gastrointestinal motility
and muscle tone. Constipation is more likely with large doses or
parenteral administration. Paralytic ileus is not likely unless the
drugs are given to clients who already have decreased gastrointestinal motility.
e. Decreased oral and respiratory tract secretions, which cause
mouth dryness and thick respiratory secretions
Mouth dryness is more annoying than serious in most cases and is
caused by decreased salivation. However, clients with chronic
lung disease, who usually have excessive secretions, tend to retain
them with the consequence of frequent respiratory tract infections.
f. Urinary retention
This reaction is caused by loss of bladder tone and is most likely
to occur in elderly men with enlarged prostate glands. Thus, the
drugs are usually contraindicated with prostatic hypertrophy.
g. Hot, dry skin; fever; heat stroke
These effects are due to decreased sweating and impairment of the
normal heat loss mechanism. Fever may occur with any age group.
Heat stroke is more likely to occur with cardiovascular disease,
strenuous physical activity, and high environmental temperatures,
especially in elderly people.
h. Ocular effects-mydriasis, blurred vision, photophobia
These are adverse effects when anticholinergic drugs are given for
conditions not related to the eyes.
4. Observe for drug interactions
a. Drugs that increase effects of anticholinergic drugs: Antihistamines, disopyramide, phenothiazines, thioxanthene agents,
tricyclic antidepressants and amantadine
These drugs have anticholinergic properties and produce additive
anticholinergic effects.
b. Drugs that decrease effects of anticholinergic drugs: Cholinergic drugs
These drugs counteract the inhibition of gastrointestinal motility
and tone induced by atropine. They are sometimes used in atropine
overdose.
Nursing Notes: Apply Your Knowledge
Answer: Although anticholinergic medications are no longer
used routinely as preoperative medication, they are still used in
some preoperative situations when decreased secretions in the
respiratory tract are important. Also, anticholinergic agents block
excessive vagal stimulation by the parasympathetic nervous system, which can occur after administration of some anesthetics or
muscle relaxants (eg, succinylcholine) or after manipulation of
the pharynx or trachea. Vagal stimulation causes bradycardia and
hypotension, and in severe cases can result in cardiac arrest.
How Can You Avoid This Medication Error?
Answer: To prevent possible complications, more information must
be obtained from Mr. Miller before the scopolamine patch can be
safely administered. If Mr. Miller has closed-angle glaucoma, administering an anticholinergic agent could result in a significant rise
in intraocular pressure and visual impairment. If it cannot be determined whether Mr. Miller has open-angle or closed-angle glaucoma,
the drug should be held. Anticholinergic medications should be used
cautiously with clients who have BPH because these drugs can
cause urinary retention. Anticholinergic medications increase heart
rate, which may not be advisable for many clients with heart disease.
Review and Application Exercises
1. How do anticholinergic drugs exert their therapeutic effects?
2. What are indications for use and contraindications for
anticholinergic drugs?
3. What is the effect of anticholinergic drugs on heart rate,
and what is the mechanism for this effect?
4. Under what circumstances is it desirable to administer
atropine before surgery, and why?
5. What are adverse effects of anticholinergic drugs?
319
6. What treatment measures are indicated for a client with an
overdose of a drug with anticholinergic effects?
7. Name two other commonly used drug groups that have
anticholinergic effects.
8. What nursing observations and interventions are needed to
increase client safety and comfort during anticholinergic
drug therapy?
SELECTED REFERENCES
Brown, J. H. & Taylor, P. (2001). Muscarinic receptor agonists and antagonists. In J. G. Hardman & L. E. Limbird. (Eds.), Goodman & Gilman’s
The pharmacological basis of therapeutics, 10th ed., pp. 155–173. New
York: McGraw-Hill.
Crabtree, B. L. & Polles, A. (1997). Substance-related disorders. In J. T.
Dipiro, R. L. Talbert, G. C. Yee, G. R. Matzke, B. G. Wells, and L. M.
Posey (Eds.), Pharmacotherapy: A pathophysiologic approach, 3rd ed.,
pp. 1345–1365. Stamford, CT: Appleton & Lange.
Drug facts and comparisons. (Updated monthly). St. Louis: Facts and
Comparisons.
Hazinski, M. F., Cummins, R. O., & Field, J. M. (Eds.). (2000). Handbook
of emergency cardiovascular care for health care providers. Dallas:
American Heart Association.
Jones, L. A. (1997). Pharmacotherapy of cardiopulmonary resuscitation. In
J. T. Dipiro, R. L. Talbert, G. C. Yee, G. R. Matzke, B. G. Wells, & L. M.
Posey (Eds.), Pharmacotherapy: A pathophysiologic approach, 3rd ed.,
pp. 181–193. Stamford, CT: Appleton & Lange.
Karch, A. M. (2002). Lippincott’s Nursing drug guide. Philadelphia:
Lippincott Williams & Wilkins.
Kelly, H. W. & Kamada, A. K., (1997). Asthma. In J. T. Dipiro, R. L. Talbert,
G. C. Yee, G. R. Matzke, B. G. Wells, & L. M. Posey (Eds.), Pharmacotherapy: A pathophysiologic approach, 3rd ed., pp. 553–590. Stamford,
CT: Appleton & Lange.
Olson, K. R. (Ed.). (1999). Poisoning and drug overdose, 3rd ed. Stamford,
CT: Appleton & Lange.
Pappano, A. J. & Katzung, B. G. (2001) Cholinoceptor-blocking drugs. In
B. G. Katzung (Ed.), Basic and clinical pharmacology, 8th ed., pp 107–119.
New York: McGraw-Hill.
Piano, M. R. & Huether, S. E. (2002). Mechanisms of hormonal regulation.
In K. L. McCance & S. E. Huether (Eds.), Pathophysiology: The biologic
basis for disease in adults and children, 4th ed., pp. 597–623. St. Louis:
Mosby.
Turkoski, B. B., Lance, B. R., & Bonfiglio, M. F. (2000–2001). Drug information handbook for nursing, 3rd ed. Hudson, OH: Lexi-Comp.

chapter Anticholinergic Drugs Objectives

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