Propranolol, a nonselective beta-blocker, was prescribed to decrease the tremor he
was experiencing. The exact action of this drug to decrease the tremor is thought to be related to its membrane-stabilizing properties. The desired therapeutic effect is the reduction of the tremor, but all of the beta-blocking effects will occur and need to be monitored. He did well on the drug until pollen season arrived. That is because propranolol, a nonselective beta-blocker, prevented the compensatory bronchodilation that occurs when the SNS is stimulated. When the pollen reacted with M.R.’s airways, causing them to swell and become narrower, his swollen bronchial tubes were unable to allow air to flow through them. The result was bronchial constriction and respiratory distress that, in M.R.’s case, progressed to a respiratory arrest. Before he began taking propranolol, M.R. probably had been effectively compensating for the swelling of the bronchi through bronchodilation and had never experienced such a reaction. There are few other drugs for treating essential tremor. M.R. and his health care providers will need to decide whether the benefit that the drug has brought to him is worth the potential for adverse effects. They might be able to suggest additional drugs to deal with the seasonal allergic reactions to make the use of propranolol safer for this patient.
M.R. may want to discuss this frightening incident with his health care provider.
He also may want to include his family in this discussion. It should be stressed that he did so well up to this point because he had not been exposed to pollen and therefore had not had the problem that brought him into the hospital this time. M.R.
probably never reported the occurrence of hay fever to his health care provider when the drug was prescribed because it had never been a problem and probably did not seem significant to him. M.R. and his family should receive support and be encouraged to talk about what happened and how they reacted to it. It is normal to feel frightened and unsure when a loved one is in distress. They should be involved in the discussion of what medical regimen would be most appropriate for M.R. at this point.
Nursing Care Guide for M.R.: Propranolol Assessment: History and Examination
Review the patient’s history for allergy to propranolol, HF, shock, bradycardia, heart block, hypotension, COPD, thyroid disease, diabetes, respiratory impairment, and concurrent use of barbiturates, NSAIDs, piroxicam, sulindac, lidocaine, cimetidine, phenothiazines, clonidine, theophylline, and rifampin.
Focus the physical examination on the following:
CV: Blood pressure, pulse, peripheral perfusion, ECG CNS: Orientation, affect, reflexes, vision
Skin: Color, lesions, texture
GU: Urinary output, sexual function
Respiratory: Respirations, adventitious sounds
Nursing Diagnoses
Decreased cardiac output related to CV effects Acute pain related to CNS, GI, systematic effects Impaired tissue perfusion, related to CV effects Deficient knowledge regarding drug therapy
Planning
The patient will receive the best therapeutic effect from the drug therapy.
The patient will have limited adverse effects to the drug therapy.
The patient will have an understanding of the drug therapy, adverse effects to anticipate, and measures to relieve discomfort and improve safety.
Implementation
Ensure safe and appropriate administration of the drug.
Provide comfort and safety measures: Assistance/side rails; temperature control;
rest periods; mouth care; small, frequent meals.
Monitor blood pressure, pulse, and respiratory status throughout drug therapy.
Taper the drug gradually if it is to be discontinued to decrease the risk of severe hypertension, MI, or stroke related to abrupt withdrawal.
Provide support and reassurance to deal with drug effects and discomfort, sexual dysfunction, and fatigue.
Provide patient teaching regarding drug name, dosage, side effects, precautions, and warning signs to report.
Evaluation
Evaluate drug effects: Blood pressure within normal limits, decrease in essential tremors, stabilized cardiac rhythm.
Monitor for adverse effects: CV effects; HF, block; dizziness, confusion; sexual dysfunction; GI effects; hypoglycemia; respiratory problems.
Monitor for drug–drug interactions as indicated.
Evaluate the effectiveness of the patient-teaching program.
Evaluate the effectiveness of comfort and safety measures.
Patient Teaching for M.R.
The drug that has been prescribed for you, propranolol, is a nonselective beta- adrenergic blocking agent. A beta-adrenergic blocking agent works to prevent certain stimulating activities that normally occur in the body in response to
such factors as stress, injury, or excitement. It stabilizes certain nerve membranes, which helps to decrease your tremor.
You should learn to take your pulse and monitor it daily, writing the pulse rate on the calendar. Your current pulse rate is 82 beats/min.
Never discontinue this medication suddenly. If you find that your prescription is running low, notify your health care provider at once. This drug needs to be tapered over time to prevent severe reactions when its use is discontinued.
Some of the following adverse effects may occur:
Fatigue, weakness: Try to stagger your activities throughout the day to allow rest periods.
Dizziness, drowsiness: If these should occur, take care to avoid driving, operating dangerous machinery, or doing delicate tasks. Change position slowly to avoid dizzy spells.
Change in sexual function: Be assured that this is a drug effect and discuss it with your health care provider.
Nausea, diarrhea: These GI discomforts often diminish with time. If they become too uncomfortable or do not improve, talk to your health care provider.
Dreams, confusion: These are drug effects. If they become too uncomfortable, discuss them with your health care provider.
Report any of the following to your health care provider: Very slow pulse, need to sleep on more pillows at night, difficulty breathing, swelling in the ankles or fingers, sudden weight gain, mental confusion or personality change, fever, or rash.
Avoid over-the-counter medications, including cold and allergy remedies and diet pills. Many of these preparations contain drugs that could interfere with this medication. If you feel that you need one of these, check with your health care provider first.
Tell any doctor, nurse, or other health care provider that you are taking these drugs, keep all medications out of the reach of children, and do not share these drugs with other people.
KEY POINTS
Beta-blockers are drugs used to block the beta-receptors within the SNS. These drugs are used for a wide range of conditions, including hypertension, stage fright, migraines, angina, and essential tremors.
Nonselective blockade of all beta-receptors results in a loss of the reflex bronchodilation that occurs with sympathetic stimulation. This limits the use of these drugs in patients who smoke or have allergic or seasonal rhinitis, asthma, or COPD.
Beta1-Selective Adrenergic Blocking Agents
Beta1-selective adrenergic blocking agents (Table 31.5) have an advantage over the nonselective beta-blockers in some cases. Because they do not usually block beta2-receptor sites, they do not block the sympathetic bronchodilation that is so important for patients with lung diseases or allergic rhinitis. Consequently, these drugs are preferred for patients who smoke or who have asthma, any other obstructive pulmonary disease, or seasonal or allergic rhinitis. These selective beta-blockers are also used for treating hypertension, angina, and some cardiac arrhythmias. Beta1-selective adrenergic blocking agents include acebutolol (Sectral), atenolol (Tenormin), betaxolol (Betoptic), bisoprolol (Zebeta), esmolol (Brevibloc), and metoprolol (Lopressor, Toprol XL).
Table 31.5 Drugs in Focus: Beta1-Selective Adrenergic Blocking Agents
MI, myocardial infarction; HF, heart failure.
Therapeutic Actions and Indications
The therapeutic effects of these drugs are related to their ability to selectively block beta1- receptors in the SNS at therapeutic doses. As a result, these drugs do not block the beta2- receptors and therefore do not prevent sympathetic bronchodilation. However, the selectivity is lost with doses higher than the recommended range.
The blockade of the beta1-receptors in the heart and in the juxtaglomerular apparatus accounts for most of the therapeutic benefits. Decreased heart rate, contractility, and excitability, as well as a membrane-stabilizing effect, lead to a decrease in arrhythmias, decreased cardiac workload, and decreased oxygen consumption. The juxtaglomerular cells are not stimulated to release renin, which further decreases blood pressure. These drugs are useful in treating cardiac arrhythmias, hypertension, and chronic angina and can help to prevent reinfarction after an MI by decreasing cardiac workload and oxygen consumption.
Beta1-selective adrenergic blocking agents in ophthalmic form are used to decrease intraocular pressure and to treat open-angle glaucoma. The beta1-selective blocker of choice depends on the condition or combination of conditions being treated and personal experience with the drugs. See Table 31.5 for Usual Indications for each drug.
Pharmacokinetics
The beta1-selective adrenergic blockers are absorbed from the GI tract after oral administration, reach peak levels directly with IV infusion, and are not usually absorbed when given in ophthalmic form. The bioavailability of metoprolol is increased if it is taken in the presence of food. These drugs are metabolized in the liver and excreted in the urine.
Metoprolol readily crosses the blood–brain barrier and may cause more CNS effects than acebutolol and atenolol, which do not cross the barrier.
Contraindications and Cautions
The beta1-selective adrenergic blockers are contraindicated in the presence of allergy to the drug or any components of the drug to avoid hypersensitivity reactions; with sinus bradycardia, heart block, cardiogenic shock, HF, or hypotension, all of which could be exacerbated by the cardiac-depressing and blood pressure–lowering effects of these drugs; and with lactation because of the potential adverse effects on the neonate. They should be used with caution in patients with diabetes, thyroid disease, or COPD because of the potential for adverse effects on these diseases with sympathetic blockade; and in pregnancy because of the potential for adverse effects on the fetus. The safety and efficacy of the use of these drugs in children have not been established.
Adverse Effects
Patients receiving these drugs often experience adverse effects related to the blocking of beta1- receptors in the SNS. CNS effects include headache, fatigue, dizziness, depression, paresthesias, sleep disturbances, memory loss, and disorientation. CV effects can include bradycardia, heart block, HF, hypotension, and peripheral vascular insufficiency.
Pulmonary effects ranging from rhinitis to bronchospasm and dyspnea can occur; these effects are not as likely to occur with these drugs as with the nonselective beta-blockers. GI upset, nausea, vomiting, diarrhea, gastric pain, and even colitis can occur as a result of unchecked parasympathetic activity and the blocking of the sympathetic receptors. GU effects can include decreased libido, impotence, dysuria, and Peyronie disease. Other effects that can occur include decreased exercise tolerance (patients often report that their “get up and go” is gone), hypoglycemia or hyperglycemia, and liver changes that are reflected in increased concentrations of liver enzymes. If these drugs are stopped abruptly after long- term use, there is a risk of severe hypertension, angina, MI, and stroke because the receptor sites become hypersensitive to catecholamines after being blocked by the drug.
Clinically Important Drug–Drug Interactions
A decreased hypertensive effect occurs if these drugs are given with clonidine, NSAIDs, rifampin, or barbiturates. If such a combination is used the patient should be monitored closely and dose adjustment made.
There is an initial hypertensive episode followed by bradycardia if these drugs are given with epinephrine. Increased serum levels and increased toxicity of intravenous lidocaine will occur if it is given with these drugs.
An increased risk for orthostatic hypotension occurs if these drugs are taken with prazosin. If this combination is used the patient must be monitored closely and safety precautions taken.
The selective beta1-blockers have increased effects if they are taken with verapamil, cimetidine, methimazole, or propylthiouracil. The patient should be monitored closely and appropriate dose adjustment made.
Prototype Summary:Atenolol
Indications: Treatment of angina pectoris, hypertension, MI; off-label uses are prevention of migraine headaches, alcohol withdrawal syndrome, and supraventricular tachycardias.
Actions: Blocks beta1-adrenergic receptors, decreasing the excitability of the heart, cardiac output, and oxygen consumption; decreases renin release, which lowers blood pressure.
Pharmacokinetics:
T1/2: 6 to 7 hours; excreted in the bile, feces, and urine.
Adverse Effects: Allergic reaction, dizziness, bradycardia, heart failure, arrhythmias, gastric pain, flatulence, impotence, bronchospasm, decreased exercise tolerance.
Nursing Considerations for Patients Receiving Beta 1 -Selective Adrenergic Blocking Agents
Assessment: History and Examination
Assess for contraindications or cautions: Known allergies to any drug or any components of the drug to avoid hypersensitivity reactions; bradycardia or heart blocks, shock, or heart failure, which could be exacerbated by the cardiac- suppressing effects of these drugs; diabetes, thyroid disease, or chronic obstructive pulmonary disease to reduce risk of adverse effects on these conditions due to sympathetic blockade; and current status of pregnancy or lactation because of the potential effects on the fetus or neonate.
Perform a physical assessment to establish baseline status before beginning therapy to determine the effectiveness of therapy and evaluate for any potential adverse effects.
Assess neurological status, including level of orientation and sensation, to evaluate for CNS effects.
Monitor cardiac status, including pulse, blood pressure, and heart rate, to identify changes, and obtain an ECG as ordered to evaluate for changes in heart rate or rhythm.
Assess pulmonary status, including respirations, and auscultate lungs for adventitious sounds to monitor respiratory status.
Examine the abdomen and auscultate bowel sounds to evaluate GI effects.
Monitor urine output to monitor the effectiveness of cardiac output and any changes in renal perfusion.
Monitor the results of laboratory tests, including electrolyte levels, to monitor for risk of arrhythmias, and renal and hepatic function studies to determine the need for possible dose adjustment.
Nursing Diagnoses
Nursing diagnoses related to drug therapy might include the following:
Decreased cardiac output related to CV effects Ineffective tissue perfusion related to CV effects Risk for injury related to CNS effects
Activity intolerance related to sympathetic blocking Deficient knowledge regarding drug therapy
Planning
The patient will receive the best therapeutic effect from the drug therapy.
The patient will have limited adverse effects to the drug therapy.
The patient will have an understanding of the drug therapy, adverse effects to anticipate, and measures to relieve discomfort and improve safety.
Implementation with Rationale
Do not stop these drugs abruptly after chronic therapy, but taper gradually over 2 weeks to prevent the possibility of severe reactions. Long-term use of these drugs can sensitize the myocardium to catecholamines, and severe reactions could occur.
Consult with the physician about discontinuing these drugs before surgery because withdrawal of the drug before surgery when the patient has been maintained on the drug is controversial.
Give oral forms of the metoprolol with food to facilitate absorption.
Continuously monitor any patient receiving an IV form of these drugs to detect severe reactions to sympathetic blockade and to ensure rapid response if these reactions occur.
Arrange for supportive care and comfort measures, including rest, environmental control, and other measures, to relieve CNS effects; safety measures if CNS effects occur to protect the patient from injury; small, frequent meals and mouth care to relieve the discomfort of GI effects; and an activity program and daily energy management ideas to help to deal with activity intolerance.
Offer support and encouragement to help the patient deal with the drug regimen.
Provide thorough patient teaching, including drug name, dosage, and schedule for administration; use of drug with food or meals if appropriate; technique for ophthalmic administration if indicated; potential adverse effects, measures to avoid drug-related problems, and warning signs of problems; safety measures such as changing position slowly and avoiding driving or operating hazardous machinery; and energy conservation measures as appropriate to provide drug education and improve compliance to the drug regimen.
Evaluation
Monitor patient response to the drug (lowered blood pressure, fewer anginal episodes, lowered intraocular pressure).
Monitor for adverse effects (GI upset, CNS changes, CV effects, loss of libido and impotence, potential respiratory effects).
Evaluate the effectiveness of the teaching plan (patient can name drug, dosage, adverse effects to watch for, and specific measures to avoid them).
Monitor the effectiveness of comfort measures and compliance with the regimen.
KEY POINTS
Beta1-selective adrenergic blocking agents do not block the beta1-receptors that are responsible for bronchodilation and therefore are preferred in patients with respiratory problems.
Beta1-selective adrenergic blocking agents are used to treat hypertension and angina in extended release forms and to treat HF.
All of the adrenergic blocking drugs must be tapered when they are discontinued after long-term use. The blocking of the receptor sites makes them hypersensitive to catecholamines, and extreme hypertension, angina, MI, or stroke could occur.
SUMMARY
Adrenergic blocking agents, or sympatholytic drugs, lyse, or block, the effects of the SNS.
Both the therapeutic and the adverse effects associated with these drugs are related to their blocking of the normal responses of the SNS.
The alpha- and beta-adrenergic blocking agents block all of the receptor sites within the SNS, which results in lower blood pressure, slower pulse, and increased renal perfusion with decreased renin levels. These drugs are indicated for the treatment of essential hypertension. They are associated with many adverse effects, including the blocking of reflex bronchodilation, cardiac suppression, and diabetic reactions.
Selective adrenergic blocking agents have been developed that, at therapeutic levels, have specific affinity for alpha- or beta-receptors or for specific alpha1-, beta1-, or beta2-receptor sites. This specificity is lost at levels higher than the therapeutic range.
Alpha-adrenergic drugs specifically block the alpha-receptors of the SNS. At therapeutic levels, they do not block beta-receptors.
Nonspecific alpha-adrenergic blocking agents are used to treat pheochromocytoma, a tumor of the adrenal medulla.
Alpha1-selective adrenergic blocking agents block the postsynaptic alpha1-receptor sites, causing a decrease in vascular tone and a vasodilation that leads to a fall in blood pressure without the reflex tachycardia that occurs when the presynaptic alpha2-receptor sites are also blocked.
Beta-blockers are drugs used to block the beta-receptors within the SNS. These drugs are used for a wide range of conditions, including hypertension, stage fright, migraines, angina, and essential tremors.
Blockade of all beta-receptors results in a loss of the reflex bronchodilation that occurs with sympathetic stimulation. This limits the use of these drugs in patients who smoke or have allergic or seasonal rhinitis, asthma, or COPD.
Beta1-selective adrenergic blocking agents do not block the beta1-receptors that are responsible for bronchodilation and therefore are preferred in patients with respiratory problems.
Answers to the questions in this chapter can be found in Answers to Check Your Understanding