McKenna's Pharmacology for Nursing, 2e

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Cholinergic agonists

Learning objectives Upon completion of this chapter, you should be able to: 1. Describe the effects of cholinergic receptors, correlating these effects with the clinical effects of cholinergic agonists. 2. Describe the therapeutic actions, indications, pharmacokinetics, contraindications and cautions, most common adverse reactions and important drug–drug interactions associated with the direct- and indirect-acting cholinergic agonists. 3. Discuss the use of cholinergic agonists across the lifespan. 4. Compare and contrast the prototype drugs bethanechol, donepezil and pyridostigmine with other cholinergic agonists. 5. Outline the care considerations, including important teaching points, for people receiving a cholinergic agonist.

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Glossary of key terms acetylcholinesterase: enzyme responsible for the immediate breakdown of acetylcholine when released from the nerve ending; prevents overstimulation of cholinergic receptor sites Alzheimer’s disease: degenerative disease of the cortex with loss of acetylcholine-producing cells and cholinergic receptors; characterised by progressive dementia cholinergic agonists: responding to acetylcholine; refers to receptor sites stimulated by acetylcholine, as well as neurons that release acetylcholine miosis: constriction of the pupil; relieves intraocular pressure in some types of glaucoma myasthenia gravis: autoimmune disease characterised by antibodies to cholinergic receptor sites, leading to destruction of the receptor sites and decreased response at the neuromuscular junction; it is progressive and debilitating, leading to paralysis nerve gas: irreversible acetylcholinesterase inhibitor used in warfare to cause paralysis and death by prolonged muscle contraction and parasympathetic crisis parasympathomimetic: mimicking the effects of the parasympathetic nervous system, leading to bradycardia, hypotension, pupil constriction, increased GI secretions and activity, increased bladder tone, relaxation of sphincters and bronchoconstriction

DIRECT-ACTING CHOLINERGIC AGONISTS bethanechol carbachol pilocarpine

INDIRECT-ACTING CHOLINERGIC AGONISTS Agents for myasthenia gravis edrophonium neostigmine pyridostigmine

Agents for Alzheimer’s disease donepezil

galantamine rivastigmine