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©2013 UpToDate ® Print Email Major drug interactions with beta blockers Drug Possible effects Precautions Aluminum hydroxide gel Decreased beta-blocker adsorption and therapeutic effect Avoid beta-blocker-aluminum hydroxide combination Aminophylline Mutual inhibition Observe patient's response Amiodarone May induce cardiac arrest Combination should be used with extreme caution Antidiabetic agents Enhanced hypoglycemia; hypertension Monitor for altered diabetic response Calcium channel inhibitors (verapamil, diltiazem) Potentiation of bradycardia, myocardial depression, and hypotension Avoid use, although few patients show ill effects Cimetidine Prolongs half-life of propranolol Combination should be used with caution Clonidine Hypertension during clonidine withdrawal Monitor for hypertensive response; withdraw beta-blocker before withdrawing clonidine Digitalis glycosides Potentiation of bradycardia Observe patient's response; interactions may benefit angina patients with abnormal ventricular function Epinephrine Hypertension; bradycardia Administer epinephrine cautiously; cardioselective beta-blocker may be safer Ergot alkaloids Excessive vasoconstriction Observe patient's response; few patients show ill effects Glucagon Inhibition of hyperglycemic effect Monitor for reduced response Halofenate Reduced beta-blocking activity; induction of propranolol withdrawal rebound Observe for impaired response to beta-blockade Indomethacin Inhibition of antihypertensive response to beta-blockade Observe patient's response Isoproterenol Mutual inhibition Avoid concurrent use or choose cardiac-selective beta-blocker Levodopa Antagonism of levodopa's hypotensive and positive inotropic effects Monitor for altered response; interaction may have favorable results Lidocaine Propranolol pretreatment increases lidocaine levels with potential toxicity Combination should be used with caution; use lower doses of lidocaine Methyldopa Hypertension during stress Monitor for hypertensive episodes MAO inhibitors Uncertain, theoretical Manufacturer of propranolol considers concurrent use contraindicated Phenothazines Additive hypotensive effects Monitor for altered response, especially with high doses of phenothiazines Phenylpropranolamine Severe hypertensive reaction Phenytoin Additive cardiac depressant effects Administer IV phenytoin with great caution Quinidine Additive cardiac depressant effects Observe patient's response; few patient show ill effects Reserpine Excessive sympathetic blockade Observe patient's response Rifampin

Monitor for altered response, especially with high doses of phenothiazines Phenylpropranolamine Severe hypertensive reaction Phenytoin Additive cardiac depressant effects Administer IV phenytoin with great caution Quinidine Additive cardiac depressant effects Observe patient's response; few patient show ill effects Reserpine Excessive sympathetic blockade Observe patient's response Rifampin Increased metabolism of beta-blockers Observe patient's response Smoking Increased metabolism of beta-blockers Observe patient's response Tricyclic antidepressants Inhibits negative inotropic and chronotropic effects of beta-blockers Observe patient's response Tubocurarine Enhanced neuromuscular blockade Observe response in surgical patients, especially after high doses of propranolol