WBR0401: Difference between revisions

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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor=[[User:Gonzalo Romero|Gonzalo A. Romero, M.D.]] [mailto:gromero@wikidoc.org]
|QuestionAuthor=[[User:Serge korjian|Serge Korjian, M.D.]] (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pharmacology
|MainCategory=Pharmacology
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|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Cardiology, Vascular
|SubCategory=Cardiology, Vascular
|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?
|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. Which of the following drugs is likely to be related to the experimental drug being evaluated?
|Explanation=The anti-arrhythmic classification is commonly tested on USMLE. The classification is as follows
|Explanation=[[File:WBR401.png|center|1000px]]
[[File:WBR401.png|center|1000px]]
 
|AnswerA=Sotalol
|AnswerA=Sotalol
|AnswerAExp=Sotalol is a potasium channel blocker
|AnswerAExp=Sotalol is a potasium channel blocker
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|AnswerEExp=Mexiletine is a sodium channel blocker, which belongs to the class IB anti-arrhythmic drugs.
|AnswerEExp=Mexiletine is a sodium channel blocker, which belongs to the class IB anti-arrhythmic drugs.
|EducationalObjectives=Sotalol is a potasium channel blocker (class III) anti-arrhythmic.
|EducationalObjectives=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.
|RightAnswer=A
|RightAnswer=A
|Approved=Yes
|Approved=Yes
}}
}}

Revision as of 18:36, 3 August 2014
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. 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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