Discontinue use if signs & symptoms of cardiac arrhythmia occurs. Increased risk of serious ventricular arrhythmias or sudden cardiac death; proarrhythmia. Not to be taken by patients w/ lactose/sorbitol intolerance, galactosemia or glucose/galactose malabsorption. Not to be taken simultaneously w/ antacids or antisecretory agents. Concomitant use w/ QT-prolonging drugs, potent CYP3A4 inhibitors, antacids or antisecretory agents. May affect ability to drive & use machines. Severe renal impairment. Pregnancy. Not recommended during lactation. Infant & childn <12 yr, <35 kg.