Some of the medications that can lead to trandolapril-verapamil ER drug interactions include neuromuscular blocking agents; potassium-sparing diuretics, such as spironolactone, triamterene, and amiloride; and beta blockers, such as metoprolol, propranolol, atenolol. Among other things, these interactions can cause your blood pressure to decrease too much, contribute to kidney damage in some people, and lead to side effects like headaches and dizziness.