ITS PLASMA CONCENTRATION IS REDUCED BY RIFAMPICIN, PHENYTOIN ETC. ENZYME INHIBITORS LIKE CIMETIDINE, QUINIDINE, HIV PROTEASE INHIBITORS MAY INCREASE PLASMA CONCENTRATION. PROPAFENONE MAY INCREASE THE PLASMA CONCENTRATION OF MANY DRUGS LIKE BETABLOCKERS, CYCLOSPORIN, DESIPRAMINE, DIGOXIN,THEOPHYLLINE AND WARFARIN. THERE MAY BE AN INCREASED RISK OF ARRHYTHMIAS IF GIVEN WITH OTHER ARRHYTHMOGENIC OR ANTIARRHYTHMIC DRUGS.