This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pharmacology
Quinidine belongs to class antiarrhythmic drug is 
Select and explain. 
A. Class I, B. Class II, C. Class III, D. Class IV
A: Class I
Answer: A: Class I 
Explanation: i.e. (class I): (510-17-KDT 6th) (367-68-MDT-l1)ANTIARRHYTHMIC DRUGSClass Ia Sodium channel blockers* Depress phase O depolarization* Slow conduction, prolong repolarization Drugs* Quinidine, Procainamide, Disopyramide, MoricizineClass Ib * Shorten repolarization Drugs* Lidocaine, MexiletineClass IC * Depress phase O repolarization, slow conduction* Propafenone is a week calcium channel blocker and b-blockers and prolongs action potential and refractionariness Drugs* Flecainide, PropafenoneClass II b-blockers* Slow AV conduction Drugs* Esmolol, Propanolol, MetoprololClass III * Prolong action potential* Prolong repolarization and ERP Drug* Amiodarone, Bretylium (also class II) Dofetilide, Ibutilide, Dronedarone, SotalolClass IV Calcium Channel blockers Drugs* Verapamil, diltiazem