Drug Interaction Report

Using probucol together with propafenone can increase the risk of an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. You may be more susceptible if you have a heart condition called congenital long QT syndrome, other cardiac diseases, conduction abnormalities, or electrolyte disturbances (for example, magnesium or potassium loss due to severe or prolonged diarrhea or vomiting). Talk to your doctor if you have any questions or concerns. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with these medications, whether together or alone. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Consumption of grapefruit, grapefruit juice, and supplements that contain grapefruit should be avoided during treatment with propafenone as they may increase the blood levels of propafenone in some patients. This can cause serious side effects such as new or worsening irregular heart rhythm or heart failure; chest pain; difficulty breathing; fluid retention and swelling; and slow heart rate and pulse. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.