Which of the following is not related to a drug toxicity of Atenolol?

Question

Options

• ACHF
• BTachycardia
• CAV block
• DSedative appearance

• A
  3% (1)
• B
  83% (25)
• C
  10% (3)
• D
  3% (1)

Explanation

Tachycardia (B) is the correct answer because atenolol, a selective beta-1 adrenergic blocker, causes bradycardia - the opposite of tachycardia. By blocking beta-1 receptors in the sinoatrial node, it slows the heart rate, so tachycardia is never a toxicity concern.

The distractors are all genuine atenolol toxicities:

• A (CHF): Atenolol's negative inotropic effect reduces cardiac contractility, which can precipitate or worsen heart failure.
• C (AV block): Beta-blockade slows conduction through the AV node, potentially causing 1st, 2nd, or 3rd degree AV block.
• D (Sedative appearance): Overdose or toxicity can produce fatigue, lethargy, and a sedated appearance due to reduced cardiac output and some CNS penetration.

Memory tip: Think "beta-blockers BLOCK the 'fight-or-flight' response" - everything slows (heart rate ↓, conduction ↓, contractility ↓). Tachycardia is a fight-or-flight response, so it's the one thing a beta-blocker cannot cause as a toxicity.

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