DRUG INTERACTIONS: Inform your doctor about all the medicines you use (both prescription and nonprescription), especially of: other medicines to treat irregular heartbeats (antiarrhythmics), beta-blockers (e.g., propranolol), cimetidine, digoxin. Do not start or stop any medicine without doctor or pharmacist approval.

OVERDOSE: If overdose is suspected, contact your local poison control center or emergency room immediately. US residents can call the US national poison hotline at 1-800-222-1222. Canadian residents should call their local poison control center directly. Symptoms of overdose may include nausea, vomiting, seizures, slow heartbeat, and fainting.

NOTES: Your doctor may want you to check your pulse rate every day while you take this medication. Learn how to monitor your pulse. To evaluate the effectiveness of this medication, your doctor may periodically take a blood sample to measure the amount of the drug in your body. Tests such as chest x-ray, eye exams or electrocardiogram (EKG) may also be done. Keep all appointments with your doctor.

MISSED DOSE: If you miss a dose, take as soon as remembered; do not take if it is almost time for the next dose, instead, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

STORAGE: Store at room temperature away from sunlight and moisture.

MEDICAL ALERT: Your condition can cause complications in a medical emergency. For enrollment information call MedicAlert at 1-800-854-1166 (USA), or 1-800-668-1507 (Canada).