McKenna's Pharmacology for Nursing, 2e

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

TABLE 31.4

DRUGS IN FOCUS Non-selective beta-adrenergic blocking agents

Drug name

Dosage/route

Usual indications

nebivolol (Nebilet)

Initially 5 mg/day PO, increase at 2-week intervals based on person’s response; maximum dose 10 mg/day 20-40 mg PO b.d. or t.d.s.; up to 320 mg daily depending on individual response Initially 5 mg PO b.d., to a maximum of 60 mg/day PO Dose varies widely based on indication; check drug guide for specific information

Treatment of hypertension, alone or as part of combination therapy in adults

oxprenolol (Corbeton)

Treatment of angina pectoris, cardiac arrhythmias, hypertension Treatment of hypertension in adults Treatment of hypertension, angina, idiopathic hypertrophic subaortic stenosis (IHSS)–induced palpitations, angina and syncope, certain cardiac arrhythmias induced by catecholamines or digoxin, phaeochromocytoma; prevention of reinfarction after MI; prophylaxis for migraine headache (which may be caused by vasodilation and is relieved by vasoconstriction, although the exact action is not clearly understood); prevention of stage fright (which is a sympathetic stress reaction to a particular situation); and treatment of essential tremors Treatment of potentially life-threatening ventricular arrhythmias; maintenance of normal sinus rhythm in people with atrial fibrillation/flutter Treatment of hypertension; prevention of reinfarction after MI; prophylaxis for migraine; in ophthalmic form, reduction of intraocular pressure in open-angle glaucoma

pindolol (Visken)

propranolol (Inderal)

sotalol (Cardol, Sotacor)

160 mg/day PO in two divided doses. Usual range 160–320 mg/day PO

timolol (Nyogel, Tenopt)

10 mg PO b.d., increases based on person’s response; 1–2 drops (gtt) in affected eye(s) for glaucoma

occur with propranolol. These drugs are all excreted in the urine. Contraindications and cautions Non-selective beta-adrenergic blocking agents are con- traindicated in the presence of allergy to any of these drugs or any components of the drug being used to avoid hypersensitivity reactions ; with bradycardia or heart blocks, shock or HF, which could be exacerbated by the cardiac-suppressing effects of these drugs ; with bronchospasm, chronic obstructive pulmonary disease (COPD) or acute asthma, which could worsen due to the blocking of the sympathetic bronchodilation ; with pregnancy because teratogenic effects have occurred in animal studies with all of these drugs except sotalol and because neonatal apnoea, bradycardia and hypoglycae­ mia could occur ; and with breastfeeding because of the potential effects on the neonate, which could include slowed heart rate, hypotension and hypoglycaemia. The safety and efficacy for use of these drugs in children have not been established. These drugs should be used cautiously in individ- uals with diabetes and hypoglycaemia because of the

blocking of the normal signs and symptoms of hypo­ glycaemia and hyperglycaemia ; with thyrotoxicosis because of the adrenergic blocking effects on the thyroid gland ; or with renal or hepatic dysfunction, which could interfere with the excretion and metabolism of these drugs. Adverse effects People receiving these drugs often experience adverse effects related to blockage of beta-receptors in the SNS. CNS effects include headache, fatigue, dizziness, depres- sion, paraesthesias, sleep disturbances, memory loss and disorientation. Cardiovascular effects can include bradycardia, heart block, HF, hypotension and periph- eral vascular insufficiency. Pulmonary effects can range from difficulty breathing, coughing and bronchospasm to severe pulmonary oedema and bronchial obstruction. GI upset, nausea, vomiting, diarrhoea, gastric pain and even colitis can occur as a result of unchecked parasym- pathetic activity and the blocking of the sympathetic receptors. Genitourinary effects can include decreased libido, impotence, dysuria and Peyronie’s disease. Other effects that can occur include decreased exercise