McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 3 3 Anticholinergic agents

TABLE 33.1

DRUGS IN FOCUS Anticholinergic agents/parasympatholytics

Drug name

Dosage/route

Usual indications

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 Mydriasis and cyclopegia for diagnostic procedures, preoperative or postoperative 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 Relief of GIT, renal and biliary spasm, motion sickness 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 Maintenance treatment of bronchospasm associated with chronic obstructive pulmonary disease (COPD); nasal spray for symptomatic relief of perennial and seasonal rhinitis To decrease GI secretions and stop GI spasms in conditions that would benefit from these actions

atropine (generic)

cyclopentolate (Cyclogyl)

1 gutte into eye

glycopyrrolate (Robinul)

Adults: 0.2–0.4 mg/kg IV or IM before surgery Paediatric: 0.004–0.005 mg/kg IV during surgery

hyoscine (Buscopan)

20 mg PO q.i.d

hyoscyamine (Donnatab)

1–2 tabs PO t.d.s. or q.i.d

ipratropium (Atrovent)

500 mcg t.d.s. to q.i.d. by inhalation; two inhalations by aerosol (do not exceed 12 inhalations per day)

propantheline

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 Inhalation of the contents of one capsule (18 mcg) each day using an inhalation device

(Pro-Banthine)

tiotropium (Spiriva)

Maintenance treatment of bronchospasm associated with COPD, for long-term use

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

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.