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Related Concept Videos

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers01:12

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers

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Class III antiarrhythmic drugs are a group of medications that can prolong action potentials in the heart. They achieve this by blocking potassium channels or enhancing inward currents from sodium channels. However, these drugs have a unique property of "reverse use-dependence," which is most pronounced at slower heart rates and can lead to torsades de pointes—a specific type of arrhythmia. However, it is essential to note that excessive QT interval prolongation—a measure of...
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Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers01:20

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Class IV antiarrhythmic drugs, such as verapamil and diltiazem, block calcium channels. They primarily affect the heart, slowing the conduction in calcium-dependent tissues like the SA and AV nodes. These drugs manage reentrant supraventricular tachycardia (SVT) and reduce ventricular rate in atrial flutter/fibrillation.
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...
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Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers01:22

Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers

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Class I antiarrhythmic drugs are used to treat various types of arrhythmias or irregular heart rhythms. These drugs block the sodium (Na+) channels in the cardiac cells, thereby affecting the movement of electrical impulses across the heart. Class I antiarrhythmic drugs are divided into three subgroups: Class IA, Class IB, and Class IC, each with distinct mechanisms of action and effects on the heart.
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...
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Pharmacokinetics: Drug–Drug Interactions01:25

Pharmacokinetics: Drug–Drug Interactions

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Drug interactions occur when the pharmacological effect of one drug is altered by another substance, either enhancing or diminishing its activity. The drug whose activity is altered is known as the object drug, and the substance causing the alteration is called the agent drug or the precipitant. The net effects of these interactions are mostly undesirable, leading to decreased effectiveness or increased adverse effects. In rare cases, interactions can be beneficial, such as the enhanced...
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Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers01:24

Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers

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Adrenergic stimulation generally impacts cardiac rate and rhythm. Specifically, stimulation of the β-adrenoceptors triggers an increase in intracellular calcium ion influx and pacemaker currents, which may cause arrhythmias. Catecholamines like adrenaline also demonstrate β2-adrenoceptor-mediated hypokalemia, impacting cardiac action potential and disrupting the normal cardiac rhythm. Class II antiarrhythmic drugs are β-adrenoceptor antagonists or β-blockers, which...
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Antiepileptic Drugs: Potassium Channel Activators01:20

Antiepileptic Drugs: Potassium Channel Activators

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Ezocgabine or retigabine, an antiepileptic drug of remarkable efficacy, has revolutionized the management of seizures. It is a potassium channel activator, explicitly targeting the family of Q subtype potassium channels. It enhances the transmembrane potassium currents, regulating neuronal excitability. This action stabilizes the resting membrane potential, a pivotal factor in mitigating the hyperexcitability that characterizes epilepsy.
Ezogabine has gained approval as an adjunctive treatment...
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Electrocardiogram Recordings in Anesthetized Mice using Lead II
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Drug-Induced QTc Prolongation.

Fady S Riad1, Andrew M Davis2, Michael P Moranville2

  • 1Department of Internal Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

The American Journal of Cardiology
|January 28, 2017
PubMed
Summary
This summary is machine-generated.

Hospitalized patients on known QTc prolonging medications show a high prevalence of QTc prolongation. This highlights potential issues with medication awareness and quality of care in managing cardiac risks during hospital stays.

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Area of Science:

  • Cardiology
  • Clinical Pharmacology
  • Hospital Medicine

Background:

  • QTc prolongation is common and linked to increased mortality.
  • Hospitalized patients often receive QTc-prolonging medications, even with existing QTc abnormalities.
  • Real-world data on the risk of QTc prolongation in hospitals is limited.

Purpose of the Study:

  • To determine the degree and relative risk of QTc prolongation in hospitalized patients receiving "known risk" medications.
  • To analyze QTc prolongation rates associated with specific medication risk categories from the Arizona Center for Education and Research on Therapeutics (AzCERT).

Main Methods:

  • Retrospective analysis of electronic medical records for 14,804 patients admitted to the University of Chicago in 2011 who received an electrocardiogram.
  • Evaluation of the longest QTc interval and medications administered within 24 hours prior to the ECG.
  • Classification of medications into four categories based on AzCERT risk levels.

Main Results:

  • Patients on "known risk" medications had significantly longer mean QTc intervals compared to those not on risk medications (Men: 485 vs 454 ms; Women: 469 vs 453 ms).
  • The rate of QTc prolongation was substantially higher in patients receiving "known risk" medications (Men: 71% vs 48%; Women: 50% vs 34%).
  • No significant increase in QTc prolongation was observed for patients receiving multiple QT-relevant drugs or those on "conditional" or "possible" risk medications.

Conclusions:

  • A high prevalence of significant QTc prolongation exists in hospitalized patients prescribed "known risk" medications.
  • These findings suggest potential deficiencies in healthcare provider awareness or overall quality of care regarding QTc-prolonging drug management.
  • Further investigation into medication stewardship protocols for QTc-prolonging agents in hospital settings is warranted.