Medical Pharmacology Practice Questions: Antiarrhythmic Dugs

Concerning the pharmacology of adenosine and related compounds,which one(s) of the following statements is/are correct?
1. Adenosine is a naturally occurring nucleoside.
2. Bolus injection of adenosine is often effective in treating reentrant supraventricular arrhythmias.
3. Adenosine may be effective in producing during some surgical procedures a controlled hypotension.
4. A & C
5. A & B
6. A, B & C
Which one(s) of the following statements best describe(s) the mechanism of action of adenosineas an antiarrhythmic agent?
1. Adenosine acts through specific G protein-coupled ß-adrenergic receptors
2. Adenosine activates acetylcholine sensitive potassium currents in the atrium as well as in the SA and AV nodes.
3. Adenosine enhances electrophysiological effects of intracellular cyclic AMP secondary to sympathetic stimulation.
4. Adenosine increases calcium currents and exerts antiarrhythmic activity by decreasing AV nodal refractoriness and by inhibiting delayed afterdepolarizations caused by sympathetic activity.
5. A&C
6. D only
Which one(s) of the following effects occur(s) after adenosine bolus administration?
1. Transient decrease in sinus rate
2. Transient decrease in AV nodal conduction velocity
3. Transient increase in AV nodal refractoriness.
4. A&C
5. A&B
6. A,B & C
Adverse effects associated with adenosine administered by bolus infusion to manage supraventricular tachyarrhythmia.
1. Dyspnea
2. Bronchospasm
3. Both
4. Neither
Characteristics of adenosine elimination:
1. Half-life of seconds due to carrier-mediated uptake.
2. Metabolism by adenosine deaminase
3. Both
4. Neither
Drug-drug interactions associated with adenosine:
1. Dipyridamole administration enhances adenosine effects since dipyridamole is an adenosine uptake inhibitor.
2. Caffeine activates adenosine receptors. Thus less adenosine is required.
3. Both
4. Neither