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BBC pharm
Ch 31: antiarrhythmic drugs
| Question | Answer |
|---|---|
| what are the four classes of antiarrhythmics? | sodium channel blocker, beta blocker, potasium channel blocker, calcium channel blocker |
| what are the class 1 antiarrhythmics? | sodium channel blockers. |
| effect of sodium channel blockers? | thye decrease the upstroke (Na entry) during depolarization and, overall, decrease cardiac action potential amplitude. many also cause a prolongaqtion of the AP. all cause a decrease in conduction velocity in injuured tissues (normal tissue not affected) |
| with sodium channel blockers, the decrease in conduction velocity in injured tissues also increases the chance for what? | re-enterant arrhythmias. |
| what are the thee classes of class 1 antiarrhythmics? | class 1A, 1B, 1C |
| what are the class 1A antiarrhythmatics? | quinidine, procainamide. |
| thi sis effective for both atrial and ventricular tachycardias | quinidine |
| this is used for ventricular and supraventricular tachycardias. | procainamide |
| class 1B antiarrhythmatics? | lidocaine, phenytoin. the later is rarely used as antiarrhythmics. |
| though this is commonly used as antiarrhythmatic, it is used for ventricular tachycardia or ventricular fibrillation. all drugs in this class mildly slow phase 0 while significantly shortening phase 3 repolarization (shortened action potential). | lidocaine |
| what are class 1C antiarrhythmics? | flecainide |
| what is flecainaide effective for? | minimizing the chance of ectopic beats in ventricle. however, bc it is also pro-arrhythmic, it is rarely used because of the risk of causing death. all drugs in this class work like class 1A drugs, except their effect on phase 0 is much more profound. |
| class II antiarrhythmic agents? | beta one antagonists. no effective as antiarrhythmics, they improve overall survival by decreasing sympathetic tone of the heart. (propanolol) |
| why is metoprolol preferred as a class II antiarrhythmic? | because it is a beta one specific BB. it can be used post MI prophylactically because the number one cause of death post MI is arrhythmia. dminishes automaticity. |
| beta blockers are particulasrly suited to treat what kind of tachyarrhythmias? | sympathetically driven tachyarrhythmias, as well as atrial fibrillation, atrial flutter, and AV nodal re-entrant tachycardia. |
| what are the class III antiarrhythmic agnets? | potassium channel blockers. they block potasssium outflow during repolarization. hence, te action potential duration is increased as phase 3 depolarization is prolonged. phase 0 remains unchanged. |
| result of potassium channel blockers? | the action potential is significantly prolonged; this can allow for control of an arrhythmia, but can also induce an arrhythmia. |
| examples of potassium channel blockers? | amiodarone, bretylium |
| this is the first line agent for many ventricular and supraventricular arrhythmias. it has significant side effects, most notable if used long term. | amiodarone |
| major AE of amiodarone? | pulmonary fibrosis and thyroid function derangements |
| class 4 antiarrhythmics? | calcium channel blockers. they minimize rrhythmias primarily in two ways: slow calcium conduction in tissues, they slow phase 4, yielding a prolonged actin potential. |
| what drugs belong to class 4: | verpamil, diltiazam. |
| side effects of quinidine? | potentiates digoxin toxicity because it displaces digoxin from plasma proteins. |
| AE of procainamide? | reversible drug induced lupus |
Created by:
aferdo01
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