Concomitant use w/ QTc prolonging medicinal products (eg, disopyramide, hydroquinidine, quinidine, amiodarone, dofetilide, dronedarone, ibutilide, sotalol, haloperidol, pimozide, sertindole, citalopram, escitalopram, erythromycin, levofloxacin, moxifloxacin, spiramycin, pentamidine, halofantrine, lumefantrine, cisapride, dolasetron, prucalopride, mequitazine, mizolastine, toremifene, vandetanib, vincamine, bepridil, diphemanil, methadone) & potent CYP3A4 inhibitors (eg, amprenavir, atazanavir, fosamprenavir, indinavir, ritonavir, saquinavir, ketoconazole, fluconazole, voriconazole, erythromycin, clarithromycin, telithromycin) is contraindicated. Concomitant use w/ Ca antagonists (eg, diltiazem, verapamil) is not recommended. Caution in concomitant use w/ bradycardia- & hypokalemia-inducing drugs. macrolides involved in QT-interval prolongation (ie, azithromycin & roxithromycin). Lower the oral bioavailability of antacids or antisecretory agents. May antagonize the antidyspeptic effect w/ anticholinergic drugs. Reduces the relaxant effect of atropine on the lower esophageal sphincter. May influence the absorption of concomitantly administered oral medicines eg, SR or EC formulations. Ketoconazole or oral erythromycin.