Dipyridamole (trademarked as Persantine and others) is a nucleoside transport inhibitor and a PDE3 inhibitor medication that inhibits blood clot formation when given chronically and causes blood vessel dilation when given at high doses over a short time. Medical uses
Dipyridamole is used to dilate blood vessels in people with peripheral arterial disease and coronary artery disease
Dipyridamole has been shown to lower pulmonary hypertension without significant drop of systemic blood pressure
It inhibits formation of pro-inflammatory cytokines (MCP-1, MMP-9) in vitro and results in reduction of hsCRP in patients. It inhibits proliferation of smooth muscle cells in vivo and modestly increases unassisted patency of synthetic arteriovenous hemodialysis grafts. It increases the release of tissue plasminogen activator from brain microvascular endothelial cells. It results in an increase of 13-hydroxyoctadecadienoic acid and decrease of 12-hydroxyeicosatetraenoic acid in the subendothelial matrix and reduced thrombogenicity of the subendothelial matrix. Pretreatment it reduced reperfusion injury in volunteers. It has been shown to increase myocardial perfusion and left ventricular function in patients with ischemic cardiomyopathy. It results in a reduction of the number of thrombin and PECAM-1 receptors on platelets in stroke patients. Cyclic adenosine monophosphate impairs platelet aggregation and also causes arteriolar smooth muscle relaxation. Chronic therapy did not show significant drop of systemic blood pressure. It inhibits the replication of mengovirus RNA. It can be used for myocardial stress testing as an alternative to exercise-induced stress methods such as treadmills.
This occurs by blocking the nucleoside transporter (ENT1) through which adenosine enters erythrocyte and endothelial cells.According to Association of Anaesthetists of Great Britain and Ireland 2016 guidelines, dipyridamole is considered to not cause risk of bleeding when receiving neuroaxial anaesthesia and deep nerve blocks. It does not therefore require cessation prior to anaesthesia with these techniques, and can continue to be taken with nerve block catheters in place. Overdose
Dipyridamole overdose can be treated with aminophylline: 6  or caffeine which reverses its dilating effect on the blood vessels. Symptomatic treatment is recommended, possibly including a vasopressor drug. Gastric lavage should be considered. Since dipyridamole is highly protein bound, dialysis is not likely to be of benefit. Mechanisms of action
Dipyridamole has two known effects, acting via different mechanisms of action:

Dipyridamole inhibits the phosphodiesterase enzymes that normally break down cAMP (increasing cellular cAMP levels and blocking the platelet aggregation, response to ADP) and/or cGMP. Dipyridamole inhibits the cellular reuptake of adenosine into platelets, red blood cells, and endothelial cells, leading to increased extracellular concentrations of adenosine. Experimental studies
Dipyridamole is currently undergoing repurposing for treatment of ocular surface disorders. These include pterygium and dry eye disease. The first report of topical dipyridamoles benefit in treating pterygium was published in 2014. A subsequent report of outcomes in 25 patients using topical dipyridamole was presented in 2016. See also
Acetylsalicylic acid/dipyridamole
Cilostazol


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