C Antiarrhythmic drugs 0 1. Pharmacological effects Nat channel block o muscarinic/a receptor block (AUtomaticity o depolarization slope in phase 4 l n abnormal automaticity l D(2)Conduction V: direct action, one-way two-way block 0 atrioventricular conduction T because of M receptor block (3) ERP and apd:ERP↑,APD个, ERP/APD↑ d(4 )Other effects: hypotension: a receptor block
1. Pharmacological effects Na+ channel block muscarinic / receptor block (1) Automaticity： depolarization slope in phase 4 abnormal automaticity (2) Conduction : direct action, one-way → two-way block atrioventricular conduction because of M receptor block (3) ERP and APD： ERP , APD , ERP/APD (4) Other effects: hypotension: receptor block C. Antiarrhythmic drugs
C Antiarrhythmic drugs 0 2. Clinicaluses u(1)Atrial fibrillation and flutter, pre- and post-cardioversion u conversion to sinus rhythm(pretreated with digitalis) maintaining sinus rhythm u(2)Other arrhythmias ventricular and supraventricular arrhythmias
2. Clinical uses (1) Atrial fibrillation and flutter, pre- and post-cardioversion conversion to sinus rhythm (pretreated with digitalis) maintaining sinus rhythm (2) Other arrhythmias ventricular and supraventricular arrhythmias C. Antiarrhythmic drugs
C Antiarrhythmic drugs u 3. Adverse effects a(1 Extracardiac effects: GI reactions(diarrhoea, etc) ypotension, Chichonism allerg a(2) Cardiac toxicity: prolonged QRS and QT intervals, paradoxical ventricular tachycardia, quinidine syncope 3)Arterial embolism: after cardioversion
3. Adverse effects (1) Extracardiac effects: GI reactions (diarrhoea, etc) hypotension, Chichonism, allergy (2) Cardiac toxicity: prolonged QRS and QT intervals, paradoxical ventricular tachycardia, quinidine syncope (3) Arterial embolism: after cardioversion C. Antiarrhythmic drugs
C Antiarrhythmic drugs 0 4. Drug interactions a(1 Hepatic enzyme inducers(barbiturates, phenytoin, etc ) increase the metabolism of quinidine u(2)Hepatic enzyme inhibitors(cimitidine, verapamil, etc. ) decrease the metabolism of quinidine d 3)Other drugs u nitroglycerine: postural hypotension o digoxin: reducing the dose of digoxin
4. Drug interactions (1) Hepatic enzyme inducers (barbiturates, phenytoin, etc.): increase the metabolism of quinidine (2) Hepatic enzyme inhibitors (cimitidine, verapamil, etc.): decrease the metabolism of quinidine (3) Other drugs nitroglycerine: postural hypotension digoxin: reducing the dose of digoxin C. Antiarrhythmic drugs