C H A P T E R 3 3
Anticholinergic agents
503
are discussed in Chapter 55. Hyoscyamine acts more
specifically on the receptors in the GI tract and is used
as an adjunct in the treatment of peptic ulcers, irritable
bowel syndrome and GI disorders. These agents are dis-
cussed in Chapter 58.
Pharmacokinetics
The anticholinergics are well absorbed after oral and
parenteral administration. Atropine is administered
through oral (PO), intramuscular (IM), intravenous
(IV), subcutaneous (SC) and ophthalmic routes. Pro-
pantheline is an oral drug. Glycopyrrolate is available
through oral, IM, IV and SC routes. These drugs are
widely distributed throughout the body and cross the
blood–brain barrier. Their half-lives vary with route
and drug. They are excreted in the urine.
Contraindications and cautions
Anticholinergics are contraindicated in the presence of
known allergy to any of these drugs
to avoid hypersen-
sitivity reactions
. They are also contraindicated with
any condition that could be exacerbated by blockade of
the parasympathetic nervous system. These conditions
include glaucoma
because of the possibility of increased
intraocular pressure with pupil dilation
; stenosing peptic
ulcer, intestinal atony and paralytic ileus,
all of which
could be exacerbated with a further slowing of GI
activity
; prostatic hypertrophy and bladder obstruction,
which could be further compounded by a blocking of
bladder muscle activity and a blocking of sphincter relax-
ation in the bladder
; cardiac arrhythmias, tachycardia
and myocardial ischaemia,
which could be exacer-
bated by the increased sympathetic influence, including
TABLE 33.1
DRUGS IN FOCUS Anticholinergic agents/parasympatholytics
Drug name
Dosage/route
Usual indications
atropine (generic)
0.4–0.6 mg IM, SC or IV; use caution with
older people
Paediatric: 0.1–0.4 mg IV, IM or SC based on
weight
Decrease secretions, bradycardia,
pylorospasm, ureteral colic, relaxing of
bladder, emotional lability with head
injuries, antidote for cholinergic drugs,
pupil dilation
cyclopentolate (Cyclogyl)
1 gutte into eye
Mydriasis and cyclopegia for diagnostic
procedures, preoperative or
postoperative
glycopyrrolate (Robinul)
Adults: 0.2–0.4 mg/kg IV or IM before surgery
Paediatric: 0.004–0.005 mg/kg IV during
surgery
Decrease secretions before anaesthetic or
intubation; used orally as an adjunct for
treatment of ulcers (although not drug
of choice); protects the person from the
peripheral effects of cholinergic drugs;
reverses neuromuscular blockade
hyoscine (Buscopan)
20 mg PO q.i.d
Relief of GIT, renal and biliary spasm,
motion sickness
hyoscyamine (Donnatab)
1–2 tabs PO t.d.s. or q.i.d
Adjunctive therapy to treat peptic ulcer,
overactive GI disorders; neurogenic
bladder or cystitis; parkinsonism; biliary
or renal colic; to decrease secretions
preoperatively; treatment of partial heart
block associated with vagal activity;
treatment of rhinitis or anticholinesterase
poisoning
ipratropium (Atrovent)
500 mcg t.d.s. to q.i.d. by inhalation; two
inhalations by aerosol (do not exceed
12 inhalations per day)
Maintenance treatment of bronchospasm
associated with chronic obstructive
pulmonary disease (COPD); nasal spray
for symptomatic relief of perennial and
seasonal rhinitis
propantheline
(Pro-Banthine)
15 mg PO t.d.s. 30 minutes before meals and
30 mg at night
Paediatric: as antisecretory agent, 1.5 mg/kg
per day PO in divided doses t.d.s. to q.i.d.;
as antispasmodic, 2–3 mg/kg per day PO in
divided doses q 4–6 hours and at bedtime
To decrease GI secretions and stop GI
spasms in conditions that would benefit
from these actions
tiotropium (Spiriva)
Inhalation of the contents of one capsule
(18 mcg) each day using an inhalation device
Maintenance treatment of bronchospasm
associated with COPD, for long-term use
