McKenna's Pharmacology for Nursing, 2e

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P A R T 5  Drugs acting on the autonomic nervous system

Implementation with rationale

Prototype summary: Donepezil Indications: Treatment of mild to moderate Alzheimer’s disease. Actions: Reversible cholinesterase inhibitor that causes elevated ACh levels in the cortex, which slows the neuronal degradation of Alzheimer’s disease. Pharmacokinetics: Route Onset Peak Oral Varies 2–4 hours T 1/2 : 70 hours; metabolism is in the liver, and excretion is in the urine. Adverse effects: Insomnia, fatigue, rash, nausea, vomiting, diarrhoea, dyspepsia, abdominal pain, muscle cramps. Care considerations for people receiving indirect-acting cholinergic agonists Assessment: History and examination ■ ■ Assess for contraindications or cautions: known allergies to any of these drugs to avoid hypersensitivity reactions ; arrhythmias, coronary artery disease, hypotension, urogenital or GI obstruction or peptic ulcer, which could be exacerbated by cholinergic stimulation ; recent GI or genitourinary surgery, which could limit use of the drugs because of the stimulatory effects of the parasympathetic system, which could aggravate healing ; regular use of NSAIDs, cholinergic drugs or theophylline, which could cause a drug–drug interaction ; and current status of pregnancy and breastfeeding because of potential effects to the fetus or neonate. ■ ■ Perform a physical assessment to establish baseline status before beginning therapy and to determine any potential adverse effects : assess orientation, affect, reflexes, ability to carry on activities of daily living (Alzheimer’s drugs) and vision to monitor for CNS changes related to drug therapy ; blood pressure, pulse, ECG, peripheral perfusion and cardiac output to monitor the parasympathetic effects on the vascular system ; and urinary output and renal and liver function tests to monitor drug effects on the renal system and liver, which could change the metabolism and excretion of the drugs. Refer to the Critical thinking scenario for a full discussion of care for a person who is receiving indirect-acting cholinergic agonists.

■ ■ If the drug is given intravenously, administer it slowly to avoid severe cholinergic effects. ■ ■ Maintain atropine sulphate on standby as an antidote in case of overdose or severe cholinergic reaction. ■ ■ Discontinue the drug if excessive salivation, diarrhoea, emesis or frequent urination becomes a problem to decrease the risk of severe adverse reactions. ■ ■ Administer the oral drug with meals to decrease GI upset if it is a problem. ■ ■ Mark the person’s chart and notify the surgeon if the person is to undergo surgery because prolonged muscle relaxation may occur if succinylcholine- type anaesthetics are used. The person will require prolonged support and monitoring. ■ ■ Monitor the person being treated for Alzheimer’s disease for any progress because the drug is not a cure and only slows progression ; refer families to supportive services. ■ ■ The person who is being treated for myasthenia gravis and significant others should receive instruction in drug administration, warning signs of drug overdose, and signs and symptoms to report immediately to enhance knowledge about drug therapy and to promote compliance. ■ ■ Arrange for supportive care and comfort measures, including rest, environmental control and other measures, to decrease CNS irritation ; headache medication to relieve pain ; safety measures if CNS effects occur to prevent injury ; protective measures if CNS effects are severe to prevent injury ; and small, frequent meals if GI upset is severe to decrease discomfort and maintain nutrition. ■ ■ Provide thorough teaching, including dosage, adverse effects to anticipate and measures to avoid them and warning signs of problems, as well as proper administration for each route used, to enhance knowledge about drug therapy and to promote compliance. ■ ■ Offer support and encouragement to help the person deal with the drug regimen. Evaluation ■ ■ Monitor response to the drug (improvement in condition being treated). ■ ■ Monitor for adverse effects (GI upset, CNS changes, cardiovascular changes, genitourinary changes). ■ ■ Evaluate the effectiveness of the teaching plan (person can name drug, dosage, adverse effects to watch for and specific measures to avoid them and proper administration). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen.