Possible Interaction: Disopyramide and Quinidine

“per kilogram of body weight, the contractile force was unaffected by quinidine but was depressed 42 per cent by disopyramide phosphate.”

“In vitro addition of lidocaine, disopyramide, bupivacaine and quinidine , in concentrations that are observed clinically, lead only with disopyramide to an important increase in free fraction of alfentanil (from 7 to 19%).”

“There was a small but significant increase in disopyramide serum concentration when concurrent quinidine therapy was given and a small decrease in quinidine serum concentration when disopyramide was added.”

“One patient had previously experienced an episode suggestive of quinidine induced ventricular tachycardia while the other developed ventricular tachycardia during quinidine treatment which was later exacerbated and sustained by the administration of disopyramide.”

“In digitalized patients, quinidine increases serum digoxin concentration, increases digoxin's effect on atrioventricular conduction, and produces more adverse gastrointestinal effects than procainamide, disopyramide , or mexiletine.”

“Its appearance with disopyramide is not unexpected in view of the quinidine-like effects of the latter and suggests that it should be prescribed with the same caution as quinidine.”

“We conclude that the biphasic dose response observed for APD with quinidine and disopyramide is due to the opposing effects of these agents on outward potassium and inward sodium currents and may cast some light on the clinical observation noted above.”

“… quinidine 10 microM … disopyramide 30 microM compared to a single drug, and was not changed by lignocaine 50 microM plus mexiletine 20 microM, whereas it was decreased …, whereas the combination produced an additive increase in tonic block but no change in use dependent block compared to a single drug.”

“ Quinidine inhibited the intestinal exsorption of theophylline and S‐disopyramide possibly by competition on the carrier.”