Increased blood conc w/ P-gp inhibitors. Increased AV conduction time w/ β-adrenoceptor blockers. Increased sensitivity w/ agents causing hypokalaemia or intracellular K deficiency eg, lithium salts, corticosteroids, carbenoxolone, some diuretics. Serious arrhythmias in digitalized patients w/ IV Ca. Increased risk of cardiac arrhythmias w/ sympathomimetics. Increased effects w/ amiodarone, flecainide, prazosin, propafenone, quinidine, spironolactone, macrolides (eg, erythromycin, clarithromycin), tetracyclines, gentamicin, itraconazole, isavuconazole, quinine, trimethoprim, alprazolam, indomethacin, propantheline, nefazodone, atorvastatin, cyclosporine, epoprostenol (transient), tolvaptan, conivaptan, carvedilol, ritonavir/ritonavir-containing regimens, taleprevir, dronedarone, ranolazine, telmisartan, lapatinib, ticagrelor, daclatasvir, flibanserin, mirabegron, simeprevir, velpatasvir, canagliflozin, ivacaftor, vandetanib, venetoclax, vemurafenib. Moderate increased risk of toxicity in heart failure patients w/ sennosides. Increased susceptibility to effects of suxamethonium-exacerbated hyperkalaemia. Increased AUC w/ lapatinib. Secondary increased levels w/ ARBs, ACE & COX-2 inhibitors, NSAIDs. Increased serum levels w/ verapamil, felodipine, tiapamil. Decreased effects w/ antacids, some bulk laxatives, kaolin-pectin, acarbose, neomycin, penicillamine, rifampicin, some cytostatics, metoclopramide, sulfasalazine, adrenaline, salbutamol, cholestyramine, phenytoin, St. John's wort, bupropion. supplemental enteral nutrition.