Dipyridamole

A phosphodiesterase inhibitor that blocks uptake and metabolism of adenosine by erythrocytes and vascular endothelial cells. Dipyridamole also potentiates the antiaggregating action of prostacyclin. (From AMA Drug Evaluations Annual, 1994, p752)

Dipyridamole is a phosphodiesterase inhibitor used to prevent postoperative thromboembolic events.

For as an adjunct to coumarin anticoagulants in the prevention of postoperative thromboembolic complications of cardiac valve replacement and also used in prevention of angina.

• Coronary Artery Disease (CAD)
• Postoperative Thromboembolism
• Stroke
• Transient Ischemic Attack
• Thrombotic events
• Anti-platelet Therapy

Dipyridamole, a non-nitrate coronary vasodilator that also inhibits platelet aggregation, is combined with other anticoagulant drugs, such as warfarin, to prevent thrombosis in patients with valvular or vascular disorders. Dipyridamole is also used in myocardial perfusion imaging, as an antiplatelet agent, and in combination with aspirin for stroke prophylaxis.

Dipyridamole likely inhibits both adenosine deaminase and phosphodiesterase, preventing the degradation of cAMP, an inhibitor of platelet function. This elevation in cAMP blocks the release of arachidonic acid from membrane phospholipids and reduces thromboxane A2 activity. Dipyridamole also directly stimulates the release of prostacyclin, which induces adenylate cyclase activity, thereby raising the intraplatelet concentration of cAMP and further inhibiting platelet aggregation.

70%

• 1 to 2.5 L/kg

99%

Dipyridamole is metabolized in the liver to the glucuronic acid conjugate and excreted with the bile.

40 minutes

• 2.3-3.5 mL/min/kg

Hypotension, if it occurs, is likely to be of short duration, but a vasopressor drug may be used if necessary. The oral LD₅₀ in rats is greater than 6,000 mg/kg while in the dogs, the oral LD₅₀ is approximately 400 mg/kg. LD₅₀=8.4g/kg (orally in rat)

• Avoid herbs and supplements with anticoagulant/antiplatelet activity. Examples include garlic, ginger, bilberry, danshen, piracetam, and ginkgo biloba.
• Avoid xanthines. Xanthines, found in coffee and tea, can reduce the effectiveness of this medication.
• Take with or without food. Taking dipyridamole extrended release capusels with a high-fat meal minimally reduces it's AUC and Cmax.