Dipyridamole Beta blockers

Drugs that may be affected by NSAIDs include the following Aminoglycosides, anticoagulants, ACE inhibitors, beta blockers, cyclosporine, dextromethorphan, digoxin, dipyridamole, hydantoins, lithium, loop diuretics, methotrexate, penicillamine, potassium-sparing diuretics, sympathomimetics, theophylline, thiazide diuretics. 

No adverse reactions normally occur in patients taking beta blockers who undergo dipyridamole-thallium-201 scintigraphy and echocardiography, but case reports suggest that very rarely bradycardia and asystole can occur. 

Adverse interactions occurred in another 2 patients taking beta blockers during diagnostic dipyridamole-thallium stress testing. One patient, who was taking atenolol, developed bradycardia then asystole, which was treated with aminophylline and atropine, and the other patient, who was taking metoprolol, developed bradycardia, which resolved after she was given aminophylline. ... 

These reports need to be set in a broad context. A very extensive study of high-dose dipyridamole echocardiography (10451 tests in 9 122 patients) noted significant adverse effects in only 96 patients, with major adverse reactions occurring in just 7 patients. Three of the 7 developed asystole and two of these patients were taking unnamed beta blockers. ... 

The value and safety of dipyridamole perfusion scintigraphy and echocardiography have been very extensively studied in very large numbers of patients, and reports of bradycardia and asystole, attributed to an interaction between dipyridamole and beta blockers, are sparse. It would therefore appear to be a relatively rare interaction (if such it is). 

Roach PJ, Magee MA, Freedman SB. Asystole and bracfycardia durii dipyridamole stress testing in patients receiving beta blockers. IntJ Cardiol (1993) 42,92-4. 

It has been suggested that dipyridamole inhibits cardiac conduction by autonomic dysregulation [141 ]. An interaction with beta-blockers has also been described [142 and that may have been the case here. 

Frossard M, Weiss K, Zeiner A, Leitha T. Asystole during dipyridamole infusion in patients without coronary artery disease or beta-blocker therapy. Clin Nucl Med 1997 22(2) 97-100. 

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