4.14: Beta-2 Antagonists

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Ernstmeyer & Christman (Eds.)
Chippewa Valley Technical College via OpenRN

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Propranolol is a Beta-2 antagonist.

Mechanism of Action: Propranolol is a nonselective beta blocker because of its inhibition of both Beta-1 and Beta-2 receptors.

Indications: Propranolol is used to treat high blood pressure, angina, various heart dysrhythmias (to lower the heart rate), and essential tremors. It is also used after a myocardial infarction to reduce mortality by decreasing heart workload, and in migraine prevention.

Nursing Considerations: Nonselective beta blockers must be used cautiously with patients who have co-existing asthma or chronic obstructive pulmonary disease (COPD) because of the effects on Beta-2 receptors that could potentially cause bronchoconstriction. It can also mask symptoms of hypoglycemia in diabetics. Use with caution in patients with impaired hepatic or renal function. Give immediate-release (IR) formulations on an empty stomach. Do not crush extended-release (ER) formulations. Propranolol ER is not considered a simple milligram-for-milligram substitute for conventional propranolol. Check blood pressure and apical pulse before giving drug; withhold and notify prescriber if apical pulse is less than 60 beats per minute or systolic blood pressure is less than 100 mm Hg, unless other parameters are provided. During IV administration, monitor blood pressure, ECG, and heart rate frequently. The most serious adverse effects include bronchoconstriction, hypotension, bradycardia, and signs of worsening heart failure. Other adverse effects are similar to selective beta blockers like metoprolol. Black Box Warning: Abrupt withdrawal of this drug may cause exacerbation of angina or a myocardial infarction. To discontinue this drug, gradually reduce dosage over 1 to 2 weeks.

Patient Teaching & Education: Patients should be instructed to follow the medication dosing regimen. Stopping medication therapy abruptly may cause life-threatening arrhythmias. Patients should be instructed on how to self-assess pulse and blood pressure to evaluate medication effectiveness. The medication may cause increased susceptibility to orthostatic blood pressure changes and increased sensitivity to cold.^{^[1]}

Now let’s take a closer look at the medication grid on propranolol in Table 4.14.^{^[2]}

Table 4:14 Propranolol Medication Grid
Class/Subclass	Prototype/Generic	Administration Considerations	Therapeutic Effects	Side/Adverse Effects
Beta-2 Antagonist	Nonselective B-blocker: propranolol	Contraindicated in patients with asthma, COPD, or bradycardia Use cautiously in patients who have diabetes mellitus because drug masks some symptoms of hypoglycemia Use with caution in patients with impaired hepatic or renal function Give immediate release formulations on an empty stomach Do not crush ER formulations Check BP and apical pulse before giving drug; withhold and notify prescriber if apical pulse is less than 60 or systolic blood pressure is less than 100 unless other parameters are provided During IV administration, monitor blood pressure, ECG, and heart rate frequently	Decrease blood pressure and heart rate Prevent migraines Manage tremors	Most serious: -Bronchoconstriction -Hypotension -Bradycardia -Worsening heart failure Black Box Warning: Abrupt withdrawal of drug may cause exacerbation of angina or myocardial infarction. To discontinue drug, gradually reduce dosage over 1 to 2 weeks Other adverse effects similar to metoprolol

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