Quinidine exes its action on the hea by: (A) Ca2+ channel blockade, (B) Na+ channel blockade, (C) K+ channel opening, (D) Cl- channel opening
Answer is B. It is d-isomer quinidine is used as an antiarrhythmic drug. Quinidine blocks myocardial Na channels. Class 1a group of drugs- quinidine, procainamide, disopyramide Ib: Lidocaine, phenytoin Ic-encainide, flecainide Ref: KD tripathi 8th ed.