Snapshot A 65-year-old man with atrial fibrillation presents to his primary care physician for a rash. He reports that he recently switched antiarrhythmic medications as instructed by his cardiologist. He reports to having discoloration of his skin and a burning sensation after sun exposure. On physical exam, there are blue and gray discolorations of his skin. An eye exam also reveals yellow-brown granules in the cornea. He was discontinued from the new anti-arrhythmic medication. (Amiodarone photosensitivity) Introduction Anti-arrhythmic medications are divided into 4 classes login to view 4 more bullets Anti-arrhythmics Class Drugs Mechanism Class IANa+ channel blockers DoubleQuarterPounder Disopyramide Quinidine Procainamide ↑ Action potential (AP)↑ Effective refractory period (ERP)↑ QT interval Class IBNa+ channel blockers Lettuce and Mayo Lidocaine Mexiletine ↓ AP ↓ ERP affects ischemic or depolarized tissue hence, great for post-myocardial infarction arrhythmias Class ICNa+ channel blockers Fries Please Flecainide Propafenone ↑ ERP in atrioventricular node but not in ventricular tissue Class II β-blockers Drug name - lol Selective β-blockers metoprolol, esmolol, propranolol, atenolol, and timolol esmolol is the most short-acting Nonselective α- and β-blockers carvedilol labetalol ↓ Sinoatrial and atrioventricular nodal activity ↓ cAMP and ↓ Ca2+ currents ↓ slope of phase 4 ↑ PR interval Class III K+channel blockers AIDS Amiodarone Ibutilide Dofetilide Sotalol ↑ AP ↑ ERP ↑ QT interval Class IV Ca2+channel blockers Class IV Drugs Verapamil Diltiazem ↑ ERP ↑ PR interval ↓ Conduction velocity Class I - Na+ Channel Blockers These drugs slow down conduction and ↓ slope of phase 0 depolarization Class IA (disopyramide, quinidine, and procainamide) login to view 11 more bullets Class IB (lidocaine and mexiletine) login to view 6 more bullets Class IC (flecainide and propafenone) login to view 5 more bullets Class II - β-Blockers Clinical use login to view 1 more bullet Toxicity login to view 11 more bullets Treatment for an overdose of β-blockers login to view 3 more bullets Class III - K+ Channel Blockers Clinical use login to view 4 more bullets Toxicity login to view 16 more bullets Class IV - Ca2+ Channel Blockers Clinical use login to view 2 more bullets Toxicity login to view 7 more bullets Other Anti-Arrhythmics Adenosine login to view 11 more bullets Mg2+ login to view 6 more bullets