<prompt> Which of the following acts by decreasing the action potential duration in Purkinje fibers?QuinineFlecainideAmiodaroneLignocaine  <response>: Ans. d Lignocaine Ref. KDT 6th 511; Katzung 11thTable 14-2DrugNormal cellsDepolarized cellsPolarizedHyperpola rizedCalcium channel blockadeEffect on pacemaker activitySympatholytic actionAdenosine000000AmiodaroneBretylium000Diltiazem00000Disopyramide?0Dofetilide00?000Esmolol00Na20Flecainide000Ibutilide00?000Lidocaine0?00Mexiletine0000Moricizine00Procainamide0PropafenonePropranolol00Quinidine0Sotalol000Tocainide0000Verapamil00 Clinical Pharmacologic Properties of Antiarrhythmic DrugsUsefulness in ArrhythmiasDrugEffect on SA nodal rateEffect on AV nodal refractory periodPR intervalQRS durationQT intervalSuper ventricularVentricularHalf-lifeAdenosineLittle00? 10sAmiodaroneitweeksBretylium220000-4 hDiltiazem00-4-8 hDisopyramlde1,3336-8 hDofetilide?000 None Esmolol-0010 minFlecainideNone0420 hIbulitide?000?6 hLidocaineNone 1None000None51-2 hMexiletineNone 1None000None612 hMoricizineNoneNone0None2-6 hProcainamidel333-4 hPropafenone005-7 hPropranolol008 hQuinidine 6 hSotalol07 hTocainideNone 1None000None5f12 hVerapamil00-7 h1 - May suppress diseased sinus nodes2 - Anticholinergic effect and direct depressant action3 - ESP in WPW syndrome4 - May be off in atrial arrhythmia by digitalis5 - Half life of active metabolites much longer 