ACLS Prep: Pharmacology
Final Test Review (Qns & Ans)
2025
1. Adenosine and Caffeine
A 45-year-old male with heavy coffee consumption presents with
paroxysmal supraventricular tachycardia (SVT). After vagal
maneuvers fail, adenosine is administered. Which interaction is
most likely to reduce adenosine’s efficacy in this patient?
A. Beta blockers
B. Caffeine
C. Calcium channel blockers
D. Digoxin
©2025
, ANS: B
Rationale: Caffeine is a methylxanthine that competitively
antagonizes adenosine receptors. In patients with high caffeine
intake, the efficacy of adenosine in terminating SVT may be
reduced.
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2. Adenosine and Theophylline
A 55-year-old female on chronic theophylline therapy for asthma
presents with SVT. When adenosine is given, what interaction is
expected?
A. Increased adenosine clearance
B. No interaction
C. Decreased adenosine efficacy
D. Prolonged adenosine half-life
ANS: C
Rationale: Theophylline, similar to caffeine, is a
methylxanthine and competes with adenosine at its receptors. This
results in decreased efficacy of adenosine during arrhythmia
termination.
©2025
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3. Adenosine and Dipyridamole
A patient who is taking dipyridamole for stroke prevention
experiences an SVT episode. Adenosine is administered as part of
ACLS management. How does dipyridamole affect adenosine’s
action?
A. It decreases the half-life of adenosine
B. It potentiates adenosine’s effects, leading to prolonged AV
block
C. It accelerates adenosine metabolism
D. It has no effect on adenosine’s action
ANS: B
Rationale: Dipyridamole blocks cellular uptake of adenosine,
thereby increasing its extracellular concentration and potentiating
its effects. This can prolong AV nodal block following adenosine
administration.
---
©2025
, 4. Beta Blockers Impact on Epinephrine
A 70-year-old patient on chronic non-selective beta blockers for
hypertension has a cardiac arrest. During ACLS, epinephrine is
administered. What interaction should be of concern?
A. Enhanced beta-adrenergic stimulation
B. Unopposed alpha-adrenergic effects resulting in severe
vasoconstriction
C. Increased epinephrine metabolism
D. No significant interaction
ANS: B
Rationale: Non-selective beta blockers block both beta-1 and
beta-2 receptors. When epinephrine is given, its beta-mediated
vasodilatory actions are blunted while alpha-mediated
vasoconstriction remains, potentially leading to extreme
hypertension and reduced coronary perfusion.
---
5. Chronic Beta-Blockade and Epinephrine Response
©2025
Final Test Review (Qns & Ans)
2025
1. Adenosine and Caffeine
A 45-year-old male with heavy coffee consumption presents with
paroxysmal supraventricular tachycardia (SVT). After vagal
maneuvers fail, adenosine is administered. Which interaction is
most likely to reduce adenosine’s efficacy in this patient?
A. Beta blockers
B. Caffeine
C. Calcium channel blockers
D. Digoxin
©2025
, ANS: B
Rationale: Caffeine is a methylxanthine that competitively
antagonizes adenosine receptors. In patients with high caffeine
intake, the efficacy of adenosine in terminating SVT may be
reduced.
---
2. Adenosine and Theophylline
A 55-year-old female on chronic theophylline therapy for asthma
presents with SVT. When adenosine is given, what interaction is
expected?
A. Increased adenosine clearance
B. No interaction
C. Decreased adenosine efficacy
D. Prolonged adenosine half-life
ANS: C
Rationale: Theophylline, similar to caffeine, is a
methylxanthine and competes with adenosine at its receptors. This
results in decreased efficacy of adenosine during arrhythmia
termination.
©2025
,---
3. Adenosine and Dipyridamole
A patient who is taking dipyridamole for stroke prevention
experiences an SVT episode. Adenosine is administered as part of
ACLS management. How does dipyridamole affect adenosine’s
action?
A. It decreases the half-life of adenosine
B. It potentiates adenosine’s effects, leading to prolonged AV
block
C. It accelerates adenosine metabolism
D. It has no effect on adenosine’s action
ANS: B
Rationale: Dipyridamole blocks cellular uptake of adenosine,
thereby increasing its extracellular concentration and potentiating
its effects. This can prolong AV nodal block following adenosine
administration.
---
©2025
, 4. Beta Blockers Impact on Epinephrine
A 70-year-old patient on chronic non-selective beta blockers for
hypertension has a cardiac arrest. During ACLS, epinephrine is
administered. What interaction should be of concern?
A. Enhanced beta-adrenergic stimulation
B. Unopposed alpha-adrenergic effects resulting in severe
vasoconstriction
C. Increased epinephrine metabolism
D. No significant interaction
ANS: B
Rationale: Non-selective beta blockers block both beta-1 and
beta-2 receptors. When epinephrine is given, its beta-mediated
vasodilatory actions are blunted while alpha-mediated
vasoconstriction remains, potentially leading to extreme
hypertension and reduced coronary perfusion.
---
5. Chronic Beta-Blockade and Epinephrine Response
©2025
