RT Book, Section A1 Bauer, Larry A. SR Print(0) ID 1106303514 T1 Quinidine T2 Applied Clinical Pharmacokinetics, 3e YR 2015 FD 2015 PB McGraw-Hill Medical PP New York, NY SN 9780071794589 LK accesspharmacy.mhmedical.com/content.aspx?aid=1106303514 RD 2024/03/28 AB Quinidine was one of the first agents used for its antiarrhythmic effects. It is classified as a type IA antiarrhythmic agent and can be used for the treatment of supraventricular or ventricular arrhythmias.1 After ventricular rate has been controlled, quinidine therapy can be used to chemically convert atrial fibrillation to normal sinus rhythm for a patient.2 Because of its side effect profile, quinidine is considered by many clinicians to be a second-line antiarrhythmic choice. Quinidine inhibits transmembrane sodium influx into the conduction system of the heart, thereby decreasing conduction velocity.1,3 It also increases the duration of the action potential, increases threshold potential toward zero, and decreases the slope of phase 4 of the action potential. Automaticity is decreased during quinidine therapy. The net effect of these cellular changes is that quinidine causes increased refractoriness and decreased conduction in heart conduction tissue which establishes a bidirectional block in reentrant pathways.