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Questions and Answers
What is the primary indication for the use of calcium channel blockers?
What is the effect of calcium channel blockers on the heart's contractions?
What is the effect of calcium channel blockers on arterioles?
What is the effect of calcium channel blockers on oxygen demand of the heart?
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What is the effect of calcium channel blockers on the heart rate?
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What is the bioavailability of calcium channel blockers after oral administration?
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What is the effect of calcium salts and vitamin D on calcium channel blockers?
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What is the mechanism of action of calcium channel blockers?
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What is a potential adverse reaction that verapamil and diltiazem can cause?
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What should be monitored regularly during therapy with verapamil or diltiazem?
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What should be done before giving the drug to a patient?
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What is a key nursing diagnosis for a patient taking verapamil or diltiazem?
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What should be done if the patient's systolic pressure is below 90 mmHg or their heart rate drops below 60 beats/minute?
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What is an important aspect of patient education when taking verapamil or diltiazem?
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Why should the patient be assisted with ambulation during the start of therapy?
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What should be done with sustained-release tablets?
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Study Notes
Calcium Channel Blockers
- Used to prevent angina that doesn't respond to other antianginal classes, as well as antiarrhythmics and in the treatment of hypertension.
- Examples of calcium channel blockers include amlodipine besylate, diltiazem, nicardipine, nifedipine, and verapamil.
Pharmacokinetics
- Absorbed quickly and almost completely when administered orally.
- Bioavailability is lower due to the first-pass effect.
- Highly bound to plasma proteins.
- Metabolized rapidly and almost completely in the liver.
Pharmacodynamics
- Prevent the passage of calcium ions across the myocardial cell membrane and vascular smooth-muscle cells.
- Causes dilation of the coronary and peripheral arteries, decreasing the force of the heart's contractions and reducing the workload of the heart.
- Reduces afterload, resulting in a decreased oxygen demand of the heart.
- Some calcium channel blockers (diltiazem and verapamil) also reduce the heart rate by slowing conduction through the SA and AV nodes.
Pharmacotherapeutics
- Used only for long-term prevention of angina, not for short-term relief of chest pain.
- Particularly effective for preventing Prinzmetal's angina.
Drug Interactions
- Calcium salts and vitamin D reduce the effectiveness of calcium channel blockers.
- Verapamil and diltiazem increase the risk of digoxin toxicity and enhance the action of carbamazepine.
Adverse Reactions
- Headache
- Dizziness
- Weakness
- Orthostatic hypotension
- Heart failure
- Hypotension
- Peripheral edema
- Palpitations
- Arrhythmias such as tachycardia, bradycardia, and AV block (also occur with diltiazem and verapamil)
Assessment
- Obtain a history of the patient's underlying condition before therapy and reassess regularly.
- Obtain a baseline blood pressure and pulse rate and rhythm; recheck regularly.
- Monitor the ECG when therapy starts and when the dosage is adjusted.
- Monitor the patient's vital signs frequently and assess for signs of toxicity and adverse reactions.
Key Nursing Diagnoses
- Risk for injury related to orthostatic hypotension.
- Risk for injury related to adverse reactions.
- Deficient knowledge related to drug therapy.
Planning Outcome Goals
- Risk for injury will be minimized.
- Complications from adverse reactions will be diminished.
- The patient will verbalize an understanding of drug therapy.
Implementation
- Don't crush sustained-release tablets.
- Be aware that sustained-release and extended-release medications aren't interchangeable.
- Take safety precautions if adverse CNS reactions occur.
- Withhold the dose and notify the prescriber if the patient's systolic pressure is below 90 mmHg or their heart rate drops below 60 beats/minute.
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Description
This quiz covers the properties and uses of calcium channel blockers in Pharmacology II. It includes their application in preventing angina and hypertension, as well as their role as antiarrhythmics.
