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Antiarrhythmic Drugs
Antiarrhythmic Drugs USMLE 1
Question | Answer |
---|---|
Quinidine | Class IA Sodium Channel blocker, inc AP duration, inc effective refractory period, inc qt interval |
Quinidine Tox | cinchonism - headache, tinnitus thrombocytopenia, torsades de points due to inc QT interval |
Procainamide | Class IA Sodium Channel blocker, inc AP duration, inc effective refractory period, inc qt interval |
Procainamide Tox | reversible SLE-like syndrome |
Disodyramide | Class IA Sodium Channel blocker, inc AP duration, inc effective refractory period, inc qt interval |
Antiarrhythmic Na+ channel blockers | Slow or block conduction in depolarized cells, dec slope of phase 0 depolarization, inc threshold for firing in abnormal pacemaker cells. |
Lidocaine | Class IB sodium channel blocker, dec AP duration, affect ischemic or depolarized purkinje and ventricular tissue. Useful in acute ventricular arrhythmias (post MI) and in digitalis induce arrhythmias |
Class 1B tox | local anesthetic, CNS stimulation/supression, cardi depression |
Mexiletine | Class IB sodium channel blocker, dec AP duration, affect ischemic or depolarized purkinje and ventricular tissue. Useful in acute ventricular arrhythmias (post MI) and in digitalis induce arrhythmias |
Tocainide | Class IB sodium channel blocker, dec AP duration, affect ischemic or depolarized purkinje and ventricular tissue. Useful in acute ventricular arrhythmias (post MI) and in digitalis induce arrhythmias |
Phenytoin | Class IB sodium channel blocker, dec AP duration, affect ischemic or depolarized purkinje and ventricular tissue. Useful in acute ventricular arrhythmias (post MI) and in digitalis induce arrhythmias |
Flecainide | Class 1C. no effect of AP duration. Useful in V-tachs that progress to VF and in intractable SVT. Use on patients without structural abnormalities. |
Class 1C Tox | proarrhythmic, especially post-MI (contraindicated) Significantly prolongs refractory period in AV node |
Hyperkalemia and Class 1 drugs | casues inc tox for all class 1 drugs |
Encainide | Class 1C. no effect of AP duration. Useful in V-tachs that progress to VF and in intractable SVT. Use on patients without structural abnormalities. |
Propafenone | Class 1C. no effect of AP duration. Useful in V-tachs that progress to VF and in intractable SVT. Use on patients without structural abnormalities. |
Propranolol | B-blocker (class 2) dec camp, dec calcium currents, dec slope of phase 4 in pacemakers. AV node most sensitive, inc PR interval. Use v-tach, SVT, slow ventricular rate during a-fib and a-flutter. |
Esmolol | B-blocker (class 2) dec camp, dec calcium currents, dec slope of phase 4 in pacemakers. AV node most sensitive, inc PR interval. Use v-tach, SVT, slow ventricular rate during a-fib and a-flutter. Esmolol very short acting. |
Metoprolol | B-blocker (class 2) dec camp, dec calcium currents, dec slope of phase 4 in pacemakers. AV node most sensitive, inc PR interval. Use v-tach, SVT, slow ventricular rate during a-fib and a-flutter. |
Timolol | B-blocker (class 2) dec camp, dec calcium currents, dec slope of phase 4 in pacemakers. AV node most sensitive, inc PR interval. Use v-tach, SVT, slow ventricular rate during a-fib and a-flutter. |
B-blocker tox | impotence, exacerbation of asthma, cardio effects = bradycardia, av block, CHF. CNS effects = sedation and sleep alterations. May mask signs of hypoglycemia. Treat overdose with glucagon. |
Metoprolol Tox | can cause dyslipidemia |
Sotalol | K channel blocker Class III. Inc AP duration, Inc ERP, Inc QT interval |
Sotalol Tox | torsades de pointes, excessive B block |
Ibutilide | K channel blocker Class III. Inc AP duration, Inc ERP, Inc QT interval |
Bretylium | K channel blocker Class III. Inc AP duration, Inc ERP, Inc QT interval |
Amiodarone | K channel blocker Class III. Inc AP duration, Inc ERP, Inc QT interval |
Ibutilid Tox | torsades |
Bretylium Tox | new arrhythmia, hypotension |
Amiodarone Tox | pulmonary fibrosis, hepatotoxicity, hypothroidism/hyperthyroidism (has class 1, 2, 3, 4, effects because it alters the lipid membrane. |
Verapamil | Calcium channel blocker Class IV. dec conduction velocity, inc ERP, inc PR interval. Used in prevention of nodal arrhythmias (SVT) |
Diltiazem | Calcium channel blocker Class IV. dec conduction velocity, inc ERP, inc PR interval. Used in prevention of nodal arrhythmias (SVT) |
Adenosine | inc K out of cells hyper polarizes the cells and dec I-Ca. Drug of choice for abolishing supra ventricular trachycardia. Very short acting. |
Adenosine Tox | Flushing, hypotension, chest pain |
Digoxin | Inhibition of Na/K ATPase pump leads to indirect inhibition of Na/Ca exchanger. Inc intracellular Ca and inc inotropy. Used for CHF to inc contractility and a-fib to dec conduction at AV node and depression of SA node |
Digoxin Tox | Cholinergic. ECG - inc PR, dec QT, scooping, T-wave inversion, arrhythmia, hyperkalemia. Worsened by renal failure. Quinidine dec digoxin clearance. |