Among the following, which beta-blocker possesses intrinsic sympathomimetic activity (ISA) and is therefore LEAST likely to cause resting bradycardia or cold extremities?
- A Pindolol ✓
- B Atenolol
- C Metoprolol
- D Bisoprolol
Correct answer: A. Pindolol
Explanation
Pindolol is a non-selective beta-blocker with the highest degree of intrinsic sympathomimetic activity (ISA) among commonly tested beta-blockers. ISA means pindolol is a partial agonist at beta receptors — it partially stimulates receptors even while blocking endogenous catecholamines, thus causing less resting bradycardia and less peripheral vasoconstriction (cold extremities). Atenolol, metoprolol, and bisoprolol are pure antagonists with no ISA.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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