WBR0401

Author	[[PageAuthor::Serge Korjian, M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Cardiology, SubCategory::Vascular
Prompt	[[Prompt::The mechanism of action of a novel experimental drug is under investigation. The drug is intended to treat patients with atrial and ventricular arrhythmias who cannot tolerate other therapies. After initial rat testing, the core lab determines that the active molecule acts on the transmembrane proteins that regulate the resting membrane potential of cardiomyocytes. ECG monitoring demonstrates significant, dose-dependent increase in the QT interval in treated rats. Which of the following drugs is likely to be related to the experimental drug being evaluated?]]
Answer A	AnswerA::Sotalol
Answer A Explanation	AnswerAExp::Sotalol is a potasium channel blocker
Answer B	AnswerB::Metoprolol
Answer B Explanation	AnswerBExp::Metoprolol is a beta-blocker (class II) anti-arrhythmic.
Answer C	AnswerC::Lidocaine
Answer C Explanation	AnswerCExp::Lidocaine is a sodium channel blocker, which is a class IA anti-arrhythmic.
Answer D	AnswerD::Verapamil
Answer D Explanation	AnswerDExp::Verapamil is a calcium channel blocker, which is a class IV anti-arrhythmic.
Answer E	AnswerE::Mexiletine
Answer E Explanation	AnswerEExp::Mexiletine is a sodium channel blocker, which belongs to the class IB anti-arrhythmic drugs.
Right Answer	RightAnswer::A
Explanation	[[Explanation:: Educational Objective: Sotalol is a potasium channel blocker (class III) anti-arrhythmic. References: Tamargo J, Caballero R, Gómez R, Valenzuela C, Delpón E. Pharmacology of cardiac potassium channels. Cardiovasc Res. 2004;62(1):9-33.]]
Approved	Approved::Yes
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