Dipyridamole

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.
Stroke.
A combination of dipyridamole and aspirin (acetylsalicylic acid/dipyridamole) is FDA-approved for the secondary prevention of stroke and has a bleeding risk equal to that of aspirin use alone. Dipyridamole absorption is pH-dependent and concomitant treatment with gastric acid suppressors (such as a proton pump inhibitor) will inhibit the absorption of liquid and plain tablets. Modified release preparations are buffered and absorption is not affected.
However, it is not licensed as monotherapy for stroke prophylaxis, although a Cochrane review suggested that dipyridamole may reduce the risk of further vascular events in patients presenting after cerebral ischemia.
A triple therapy of aspirin, clopidogrel, and dipyridamole has been investigated, but this combination led to an increase in adverse bleeding events.
Other uses.
Dipyridamole also has non-medicinal uses in a laboratory context, such as the inhibition of cardiovirus growth in cell culture. 
Drug interactions.
Due to its action as a phosphodiesterase inhibitor, dipyridamole is likely to potentiate the effects of adenosine. This occurs by blocking the nucleoside transporter 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 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:
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 dipyridamole's benefit in treating pterygium was published in 2014. A subsequent report of outcomes in 25 patients using topical dipyridamole was presented in 2016.