OBJECT DRUGS

• Digoxin (Lanoxin, etc.)

PRECIPITANT DRUGS

Calcium Channel Blockers:

• Bepridil (Vascor)
• Diltiazem (Cardizem, etc.)
• Verapamil (Isoptin, etc.)

Comment:

These calcium channel blockers inhibit P-glycoprotein and may reduce the renal and nonrenal elimination of digoxin. Digoxin plasma concentrations may increase substantially in some patients. Additive inhibition of A-V conduction may also occur. Nonetheless, with proper monitoring, digoxin is often used with these agents with good results.

Class 3: Assess Risk & Take Action if Necessary

• Consider Alternative:: Dihydropyridine calcium channel blockers such as amlodipine (Norvasc), felodipine (Plendil), or nifedipine (Procardia) do not appear to affect digoxin concentrations.
• Monitor: Monitor for altered digoxin effect if one of these calcium channel blockers is initiated, discontinued or changed in dosage; adjustments of digoxin dosage may be needed. Up to 10 days may be required for digoxin to achieve a new steady-state. If digoxin is initiated in the presence of therapy with one of these agents, consider conservative doses of digoxin.