Dipyridamole Aminophylline

Dipyridamole and related compounds, RA233, RA433, VK744, VK774, caffeine, papaverine, aminophylline, theophylline, methylxanthines. 

A patient with aorto-iliac occlusive vascular disease and hypertension suffered a stroke 6.5 minutes after administration of intravenous dipyridamole during a thallium myocardial study (11). Aminophylline did not reverse its progression. 

The practicability of dipyridamole A-ammonia myocardial positron emission tomography for perioperative risk assessment of coronary artery disease in patients with severe chronic obstructive pulmonary disease undergoing lung volume reduction surgery has been studied in 13 men and 7 women (mean age 57 years) without symptoms of coronary artery disease (12). Nine patients had intolerable dyspnea due to bronchoconstriction and required intravenous aminophylline. Dipyridamole cannot be recommended as a pharmacological stress in this setting. 

Clinically important, potentially hazardous interactions with aminophylline, carbamazepine, dipyridamole... 

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. ... 

Caffeine 4 mg/kg intravenously (roughly equivalent to 2 to 3 cups of coffee), given before dipyridamole-thallium-201 myocardial scintigraphy, caused a false-negative test result in a patient. A further study in 8 healthy subjects confirmed that caffeine inhibits the haemodynamic response to an infusion of dipyridamole. Similarly, oral theophylline markedly reduced the diagnostic accuracy of myocardial imaging using dipyridamole. In addition, intravenous aminophylline accelerated the myocardial washout rate of thallium-201 after a dipyridamole infusion. ... 

It appears that xanthine derivatives such as caffeine and theophylline might antagonise some of the haemodynamic effects of dipyridamole because they act as competitive antagonists of adenosine (an endogenous vasodilator involved in the action of dipyridamole). Due to these opposing effects, parenteral aminophylline has been used to treat adverse events associated with intravenous dipyridamole, - and it is recommended that aminophylline should be made available before beginning dipyridamole echocardiography. ... 

Takeishi Y, Tono-oka I, Kubota I, Ikeda K, Masakane I, Chiba J, Abe S, Tsuiki K, Tomoike H. Intravenous aminophylline affects myocardial washout of thaliium-201 after dipyridamole infusion. AmJNoninvasive Cardiol (1992) 6,116-21. 

The safety of adenosine in myocardial perfusion testing as an alternative to dipyridamole, which is contraindicated in patients with obstructive airways disease, has been examined in 46 consecutive patients who received intravenous adenosine 140 mg/kg/minute for 4 minutes only 14 complained of chest discomfort and nine had dyspnea none required intravenous aminophylline or resuscitation... 

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