Concomitant use w/ drugs known to prolong the QTc interval or induce torsades de pointes [eg, class IA (eg, quinidine, disopyramide) or class III (eg, amiodarone, sotalol, dofetilide, ibutilide)], antiarrhythmics, methadone, cisapride, moxifloxacin, antipsychotics.