SOME MEDICINES MAY INTERACT with this medicine. DO NOT TAKE THIS MEDICINE if you are taking dofetilide, or you have taken disopyramide within the past 48 hours. TELL YOUR HEALTHCARE PROVIDER if you are taking any other medicines, especially any of the following: beta-blockers (eg, propranolol), clonidine, disopyramide, ketolides (eg, telithromycin), macrolides (eg, erythromycin), ritonavir, phenobarbital, rifampin, St. John's wort, aldosterone blockers (eg, eplerenone), aspirin, carbamazepine, colchicine, cyclosporine, digoxin, doxorubicin, dronedarone, eletriptan, everolimus, flecainide, HMG-CoA reductase inhibitors (eg, lovastatin, simvastatin), lithium, narcotic pain relievers (eg, fentanyl), paclitaxel, quinazolines (eg, terazosin), quinidine, ranolazine, theophyllines, tolvaptan, or other blood pressure medicines (eg, lisinopril). This may not be a complete list of all interactions that may occur. Ask your health care provider if this medicine may interact with other medicines you take. DO NOT START OR STOP any medicine without doctor or pharmacist approval. Inform your doctor of any other medical conditions, including heart failure or other heart problems (eg, a very slow heart rate, heart block, heart valve disease), low blood pressure, kidney or liver problems, muscular dystrophy, a neuromuscular disease, allergies, pregnancy, or breast-feeding. Tell your doctor if you have had a recent heart attack with lung congestion or you are being treated for cancer. USE OF THIS MEDICINE IS NOT RECOMMENDED if you have certain heart problems (eg, left ventricular dysfunction, sick sinus syndrome, second- or third-degree heart block and do not have a pacemaker); very low blood pressure; moderate to severe congestive heart failure (CHF); atrial fibrillation or flutter and a pre-excitation syndrome (extra conduction pathway in the heart), such as Wolff-Parkinson-White (WPW) syndrome or Lown-Ganong-Levine (LGL) syndrome; or shock due to serious heart problems. This medicine should not be used in CHILDREN; safety and effectiveness in these children have not been confirmed. Contact your doctor or pharmacist if you have any questions or concerns about using this medicine.