WBR0401

Author	[[PageAuthor::Gonzalo A. Romero, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Cardiology, SubCategory::Vascular
Prompt	[[Prompt::A novel drug is being developed by a group of basic science researchers. The drug is being studied under animal models using specific cardiovascular receptors. The research team measures the drug’s effects on the ventricular membrane potential. They determine that the drug increases the action potential duration (APD) by increasing the effective refractory period (ERP). Detail molecular studies determine that the drug works by blocking the potassium channels. Which of the following drugs is an analogue of the novel drug?]]
Answer A	AnswerA::Sotalol
Answer A Explanation	[[AnswerAExp::Correct. Sotalol is a potasium channel blocker]]
Answer B	AnswerB::Metoprolol
Answer B Explanation	[[AnswerBExp::Incorrect. Metoprolol is a beta-blocker (class II) anti-arrhythmic.]]
Answer C	AnswerC::Lidocaine
Answer C Explanation	[[AnswerCExp::Incorrect. Lidocaine is a sodium channel blocker, which is a class IA anti-arrhythmic.]]
Answer D	AnswerD::Verapamil
Answer D Explanation	[[AnswerDExp::Incorrect. Verapamil is a calcium channel blocker, which is a class IV anti-arrhythmic.]]
Answer E	AnswerE::Mexiletine
Answer E Explanation	[[AnswerEExp::Incorrect.Mexiletine is a sodium channel blocker, which belongs to the class IB anti-arrhythmic drugs.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::The anti-arrhythmic classification is commonly tested on USMLE. The classification is as follows File:Anti-arrhytmic.png Educational Objective: Sotalol is a potasium channel blocker (class III) anti-arrhythmic. See also: Antiarrhythmic_agent Educational Objective: References: ]]
Approved	Approved::Yes
Keyword
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::