Additional Drugs That Interact With Calan SR
CYP 3A4 Inhibitors
Calan SR is broken down (metabolized) by certain liver enzymes known as CYP 3A4 enzymes. Other medications (known as CYP 3A4 inhibitors) that slow the activity of these enzymes can increase the level of Calan SR in the blood, perhaps leading to increased and possibly dangerous side effects. Check with your healthcare provider before taking Calan SR with any of these medications. If you have already been taking such medications with Calan SR, check with your healthcare provider before stopping them.
Digoxin (Digitek, Lanoxin)
Calan SR may increase the level of digoxin in your blood (although studies have shown conflicting results). Because changes in digoxin levels can be dangerous, your healthcare provider should closely monitor the level of digoxin in your blood and adjust your digoxin dosage as necessary. Your healthcare provider should also monitor your heart rate, as Calan SR and digoxin can both lower your heart rate.
Because both disopyramide and Calan SR decrease the heart's ability to pump blood forcefully, disopyramide should not be taken within 48 hours before, or 24 hours after, taking Calan SR.
Combining Calan SR with flecainide may decrease the heart's ability to pump blood forcefully and may decrease the heart rate too much. Your healthcare provider should monitor you closely when combining these two medications.
Grapefruit juice can increase the level of Calan SR in your blood, increasing your risk of side effects. Grapefruit juice should be avoided in most cases. However, if your healthcare provider decides that it is okay for you to drink grapefruit juice, you should do so consistently and in moderation.