Anti-Dysrhythmic Drugs

Anti-Dysrhythmic Drugs

Class I: Sodium Channel Blockers

• Divided into three subcategories: IA, IB, and IC
• IA: Quinidine, slows impulse conduction in atria, ventricles, and Purkinje fibers
• IA: Quinidine, delays repolarization, suppresses dysrhythmias, widens QRS and prolongs QT interval
• IA: Quinidine, active against supraventricular and ventricular dysrhythmias, indicated for long-term suppression
• IA: Quinidine, adverse effects include cinchonism, cardiotoxicity, and can double digoxin levels
• IB: Mexiletine, oral analogue of lidocaine, used for symptomatic ventricular dysrhythmias
• IB: Mexiletine, eliminated by hepatic metabolism, prolonged effects in liver patients, adverse effects include GI, neurologic, and can exacerbate HF
• IC: Flecainide and propafenone

Class II: Beta Blockers (BB)

• Examples include propranolol, acebutolol, esmolol, and sotalol
• Prolong QT, decrease Ca entry, and can cause HF, AV block, sinus arrest, hypotension, and bronchospasm

Class III: Potassium Channel Blockers

• Example: Amiodarone, used for life-threatening ventricular dysrhythmias, atrial and ventricular dysrhythmias
• Amiodarone, toxicity can continue for weeks-months after discontinuation, requires medication guide
• Amiodarone, adverse effects include pulmonary toxicity, liver toxicity, thyroid toxicity, and requires regular monitoring of CXR, TSH, and LFTs
• Amiodarone, widens QRS and prolongs QT and PR

Class IV: Calcium Channel Blockers (CCB)

• Examples include verapamil and diltiazem
• Used for afib or flutter, and SVT, adverse effects include bradycardia, AV block, HF, hypotension, peripheral edema, and constipation
• Elevate digoxin levels, can cause bradycardia, AV block, and HF when given with BB

Others

• Adenosine, digoxin, and ibutilide
• Digoxin, decreases conduction in AV, prolongs PR interval, and decreases automaticity in SA
• Digoxin, used only for supraventricular dysrhythmias, risk increased with hypokalemia

This quiz covers Class I anti-dysrhythmic drugs, specifically sodium channel blockers, including quinidine and its effects on the heart. Topics include impulse conduction, repolarization, and dysrhythmia suppression.