Other antihypertensive agents Additive hypotension.
Beta-blockers May result in increased hypotension and adverse effects because of additive depressant effects on myocardial contractility or AV conduction.
Buspirone Pharmacologic and adverse effects may be increased by verapamil.
Calcium salts Clinical effects and toxicities of verapamil may be reversed.
Carbamazepine Increased carbamazepine serum levels.
Cyclosporine Increased cyclosporine levels may result.
Dofetilide Risk of life-threatening ventricular arrhythmias, including torsades de pointes, may be increased. Coadministration with verapamil is contraindicated.
Digitalis glycosides Increased serum digoxin or digitoxin levels may occur.
Disopyramide Do not use 48 h before or 24 h after verapamil.
Flecainide May prolong AV conduction.
Nondepolarizing muscle relaxants Enhanced muscle relaxant effects and prolonged respiratory depression may occur.
Prazosin Increased prazosin serum levels may result.
Quinidine Hypotension, bradycardia, ventricular tachycardia, AV block, and pulmonary edema may occur.
Rifampin Loss of effectiveness of oral verapamil may occur.
Simvastatin Plasma levels may be elevated by verapamil, increasing the risk of toxicity (eg, rhabdomyolysis).
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