Which calcium channel blocker has the MOST pronounced negative chronotropic and dromotropic effect and is used in rate control of atrial fibrillation?
- A Amlodipine
- B Verapamil ✓
- C Nifedipine
- D Nimodipine
Correct answer: B. Verapamil
Explanation
Verapamil is a phenylalkylamine calcium channel blocker with the greatest selectivity for cardiac L-type calcium channels, particularly in the SA and AV nodes. This produces significant negative chronotropy and dromotropy, making it effective for rate control in supraventricular tachycardias including atrial fibrillation. Dihydropyridines like amlodipine and nifedipine are highly vascular-selective and lack significant cardiac conduction effects.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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