Antiarrhythmic Drugs Flashcards

Class II Antiarrhythmic Drugs

• Metoprolol, Propranolol, Esmolol, Atenolol, Timolol, and Carvedilol are all classified as Class II Antiarrhythmics, specifically beta-blockers.
• Esmolol is noted for its very short acting properties.
• Mechanism of action involves decreasing SA and AV nodal activity, reducing cAMP, which lowers Ca2+ currents, thereby decreasing automaticity and suppressing abnormal pacemakers.
• Clinical applications include treating supraventricular tachycardia (SVT), controlling ventricular rate in atrial fibrillation and flutter, and managing premature beats or ventricular tachycardia.
• Common toxicities include impotence, exacerbation of COPD/asthma, cardiovascular issues (bradycardia, AV block, CHF), CNS effects (sedation, sleep alterations), and masking hypoglycemia signs.
• Specific toxicities: Metoprolol can cause dyslipidemia, while Propranolol may exacerbate Prinzmetal angina and is contraindicated in cocaine users.

Class III Antiarrhythmic Drugs

• Amiodarone, Ibutilide, Dofetilide, and Sotalol are classified as Class III Antiarrhythmics and function as K+ channel blockers.
• Class III drugs increase action potential duration in Purkinje and ventricular muscle fibers by blocking K+ currents during phase 3 repolarization and raise effective refractory periods.
• Clinical uses involve treating atrial fibrillation, atrial flutter, and ventricular tachycardia; they are particularly valuable when other antiarrhythmics fail.
• Sotalol and Ibutilide can lead to torsades de pointes, with Sotalol also causing excessive beta-blockade.
• Amiodarone's toxicities include pulmonary fibrosis, hepatotoxicity, thyroid dysfunctions, corneal deposition, skin deposits causing photodermatitis, neurologic effects, constipation, and cardiovascular issues.

Special Considerations for Amiodarone

• Requires monitoring of pulmonary function tests (PFTs), liver function tests (LFTs), and thyroid function tests (TFTs).
• Notable for having combined effects characteristic of Class I, II, III, and IV drugs and alters the lipid membrane.

Class IV Antiarrhythmic Drugs

• Verapamil and Diltiazem are classified as Class IV Antiarrhythmics, functioning as calcium channel blockers.
• They decrease the rate of rise of phase 0 depolarization and conduction velocity in nodal tissue, which helps reduce reentry mechanisms.
• Clinical applications include prevention of nodal arrhythmias (like PSVT), controlling ventricular rates in atrial fibrillation and flutter, and managing multifocal atrial tachycardia.
• Class IV drugs increase effective refractory periods in the AV node and prolong the PR interval.

Explore key concepts about Class II, III, IV, and other antiarrhythmic drugs through this flashcard quiz. Test your knowledge on specific medications such as Metoprolol, Propranolol, and Esmolol. Perfect for medical students and healthcare professionals!