All of the following statements are true about quinidine except:
(Ref: KDT 6/e p511, 512) Quinidine is a class I antiarrhythmic agent. It blocks Na+ channels in the open state and also delays the recovery of these channels. Blockade by these antiarrhythmic agents is frequency dependent. Class Ia antiarrhythmics, in addition blocks myocardial K+ channels also.
It blocks myocardial Na+ channels primarily in the open state
It has no effect on myocardial K+ channels
It produces frequency dependent blockade of myocardial Na+ channels
It delays recovery of myocardial Na+ channels
Other topics and Adverse effects