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Questions and Answers
What is the mechanism of action of adenosine?
What is the mechanism of action of adenosine?
What side effect is NOT associated with adenosine?
What side effect is NOT associated with adenosine?
Which of the following statements is true regarding digoxin?
Which of the following statements is true regarding digoxin?
In which situation should the dose of adenosine be reduced by 80%?
In which situation should the dose of adenosine be reduced by 80%?
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What is a common adverse effect experienced after administration of adenosine?
What is a common adverse effect experienced after administration of adenosine?
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What effect does adenosine have on the cardiac action potential?
What effect does adenosine have on the cardiac action potential?
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What is the primary mechanism of action of digoxin?
What is the primary mechanism of action of digoxin?
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Which adverse effect is most commonly associated with adenosine administration?
Which adverse effect is most commonly associated with adenosine administration?
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In what scenario is it necessary to significantly reduce the dose of adenosine?
In what scenario is it necessary to significantly reduce the dose of adenosine?
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What is the typical onset duration of action for adenosine?
What is the typical onset duration of action for adenosine?
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What is the main mechanism by which adenosine affects cardiac myocyte excitation?
What is the main mechanism by which adenosine affects cardiac myocyte excitation?
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Which of the following side effects is commonly associated with the administration of adenosine?
Which of the following side effects is commonly associated with the administration of adenosine?
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How does digoxin influence the conduction of the AV node?
How does digoxin influence the conduction of the AV node?
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In which condition is the use of adenosine contraindicated?
In which condition is the use of adenosine contraindicated?
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What is the duration of action of adenosine after administration?
What is the duration of action of adenosine after administration?
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Study Notes
Adenosine
- Adenosine is an antiarrhythmic drug that acts by increasing potassium efflux out of the sinoatrial and atrioventricular node.
- This action raises the threshold for a cardiac action potential, making it more difficult for an action potential to be generated.
- Adenosine decreases the rate of cardiac myocyte excitation.
- Adenosine has a very short half-life of approximately 10 seconds.
- Common side effects include hyperkalemia, cardiac arrhythmias, paralysis, and shock.
- Some patients describe an impending doom feeling or that the experience is the worst they have ever experienced.
- Adenosine is used intravenously to treat paroxysmal supraventricular tachycardia (PSVT).
- It is also used in cardiac stress testing and imaging.
- The dose should be reduced by 80% in heart transplant patients.
- Adenosine is contraindicated in second or third-degree heart block.
- Precautions should be taken in patients with COPD or asthma.
- Common adverse effects include chest discomfort, flushing, dyspnea, headache, and nausea.
- Serious adverse effects include atrial fibrillation, dysrhythmias, and AV block.
- Drug interactions include theophylline, caffeine, dipyridamole, and calcium channel blockers.
- Adenosine is given as a rapid bolus dose over 1-3 seconds, which results in a rapid decrease in heart rate.
Digoxin
- Digoxin is an antiarrhythmic drug that acts by blocking the sodium-potassium ATPase pump and indirectly increasing intracellular calcium levels.
- Digoxin enhances potassium conductance and inhibits cAMP-induced calcium influx.
- This results in marked hyperpolarization and suppression of calcium-dependent action potentials.
- Digoxin decreases AV node conduction and increases the refractory period by increasing potassium conductance.
- Its effects include hyperpolarization of Phase 4 and inhibition of calcium influx (Phase 0).
Adenosine
- Adenosine increases potassium efflux out of the sinoatrial and atrioventricular nodes.
- This raises the threshold for a cardiac action potential, making it harder to generate.
- It reduces the rate of cardiac myocyte excitation.
- Adenosine has a very short half-life of approximately 10 seconds.
- Common side effects include hyperkalemia, cardiac arrhythmias, paralysis, and shock.
- It is often described as feeling like impending doom and is considered a very unpleasant experience by many.
Digoxin
- Digoxin blocks the sodium-potassium ATPase pump, indirectly increasing intracellular calcium levels.
- It enhances potassium conductance and inhibits cAMP-induced calcium influx, leading to marked hyperpolarization and suppression of calcium-dependent action potentials.
- Its net effect is a decrease in AV node conduction and an increase in the refractory period by increasing potassium conductance during phase 3, resulting in hyperpolarization of phase 4 and inhibiting calcium influx during phase 0.
Adenosine (Adenocard®)
- Adenosine is administered intravenously for the treatment of paroxysmal supraventricular tachycardia (PSVT).
- It is also used in cardiac stress testing and imaging.
- It has a half-life of 10 seconds and its dose should be reduced by 80% in heart transplant patients.
- Contraindications include second or third-degree heart block.
- Precautions should be taken in patients with COPD or asthma.
- Common side effects include chest discomfort, flushing, dyspnea, headache, and nausea.
- Serious side effects include atrial fibrillation, dysrhythmias, and AV block.
- It is commonly given as a rapid bolus dose over 1-3 seconds, resulting in a rapid decrease in heart rate.
- Interactions exist with theophylline, caffeine, dipyridamole, and calcium channel blockers.
Adenosine
- Increases potassium (K+) efflux out of the sinoatrial (SA) and atrioventricular (AV) nodes.
- Raises the threshold for a cardiac action potential.
- Makes it more difficult for an action potential to be generated.
- Reduces the rate of cardiac myocyte excitation.
- Short-acting drug with a half-life of approximately 10 seconds.
- Common side effects include chest discomfort, flushing, dyspnea, headache, and nausea.
- Serious side effects include atrial fibrillation, dysrhythmias, and AV block.
- Contraindicated in 2nd or 3rd degree heart block.
- Precautions for patients with Chronic Obstructive Pulmonary Disease (COPD) or Asthma.
- Drug interactions include theophylline, caffeine, dipyridamole, and calcium channel blockers.
- Administered as a rapid bolus dose over 1-3 seconds.
Digoxin
- Blocks sodium (Na+)/potassium (K+) -ATPase, indirectly increasing intracellular calcium (Ca2+).
- Enhances potassium (K+) conductance and inhibits cyclic adenosine monophosphate (cAMP)-induced calcium (Ca++) influx.
- Marked hyperpolarization and suppression of calcium (Ca++)-dependent action potential.
- Decreases AV node conduction and increases refractory period.
- Increases potassium (K+) conductance, leading to hyperpolarization during phase 3 (repolarization) of the action potential.
- Inhibits calcium (Ca++) influx during phase 0 (depolarization) of the action potential.
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Description
This quiz explores the drug Adenosine, focusing on its mechanism of action, applications in treating paroxysmal supraventricular tachycardia (PSVT), and potential side effects. Test your knowledge on its pharmacokinetics, contraindications, and precautions for use in specific patient populations.
