== Quinidine == 

 Not previously knowing even of the existence of quinidine I came upon this article and found it puzzling and uninformative, even evasive. Eventually I sorted it out I think. 

 But my attempt to clarify and save those that follow the trouble has been reverted,  I'm sure with good reasons. It seems to me that a link to quinidine would be helpful. Would someone else like to have a go?