|Trade names||Persantine, others|
|By mouth, IV|
|Elimination half-life||α phase: 40 min,|
β phase: 10 hours
|Excretion||Biliary (95%), urine (negligible)|
|Chemical and physical data|
|Molar mass||504.636 g·mol−1|
|3D model (JSmol)|
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.
- 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[clarification needed] 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.
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.
- Vasodilation occurs in healthy arteries, whereas stenosed arteries remain narrowed. This creates a "steal" phenomenon where the coronary blood supply will increase to the dilated healthy vessels compared to the stenosed arteries which can then be detected by clinical symptoms of chest pain, electrocardiogram and echocardiography when it causes ischemia.
- Flow heterogeneity (a necessary precursor to ischemia) can be detected with gamma cameras and SPECT using nuclear imaging agents such as Thallium-201, Tc99m-Tetrofosmin and Tc99m-Sestamibi. However, relative differences in perfusion do not necessarily imply any absolute decrease in blood supply in the tissue supplied by a stenosed artery.
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.
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.
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.
- Nielsen-Kudsk, F; Pedersen, AK (May 1979). "Pharmacokinetics of Dipyridamole". Acta Pharmacologica et Toxicologica. 44 (5): 391–9. doi:10.1111/j.1600-0773.1979.tb02350.x. PMID 474151.
- "Aggrenox (aspirin/extended-release dipyridamole) Capsules. Full Prescribing Information" (PDF). Boehringer Ingelheim Pharmaceuticals, Inc. Retrieved 1 December 2016.
- "Dipyridamole" at Dorland's Medical Dictionary
- Brown DG, Wilkerson EC, Love WE (March 2015). "A review of traditional and novel oral anticoagulant and antiplatelet therapy for dermatologists and dermatologic surgeons". Journal of the American Academy of Dermatology. 72 (3): 524–34. doi:10.1016/j.jaad.2014.10.027. PMID 25486915.
- Dixon BS, Beck GJ, Vazquez MA, et al. (2009). "Effect of dipyridamole plus aspirin on hemodialysis graft patency". N Engl J Med. 360 (21): 2191–2201. doi:10.1056/nejmoa0805840. PMC 3929400. PMID 19458364.
- Dipyridamole in the laboratory: Fata-Hartley, Cori L.; Ann C. Palmenberg (2005). "Dipyridamole reversibly inhibits mengovirus RNA replication". Journal of Virology. 79 (17): 11062–11070. doi:10.1128/JVI.79.17.11062-11070.2005. PMC 1193570. PMID 16103157.
- Russell TL, Berardi RR, Barnett JL, O’Sullivan TL, Wagner JG, Dressman JB. pH-related changes in the absorption of "dipyridamole" in the elderly. Pharm Res (1994) 11 136–43.
- Derendorf H, VanderMaelen CP, Brickl R-S, MacGregor TR, Eisert W. "Dipyridamole" bioavailability in subjects with reduced gastric acidity. J Clin Pharmacol (2005) 45, 845–50.
- "Archived copy". Archived from the original on 2009-07-05. Retrieved 2010-02-06.CS1 maint: archived copy as title (link)
- Stockley, Ivan (2009). Stockley's Drug Interactions. The Pharmaceutical Press. ISBN 978-0-85369-424-3.
- De Schryver EL, Algra A, van Gijn J (2007). Algra A (ed.). "Dipyridamole for preventing stroke and other vascular events in patients with vascular disease". Cochrane Database of Systematic Reviews (2): CD001820. doi:10.1002/14651858.CD001820.pub3. PMID 17636684.
- Sprigg N, Gray LJ, England T, et al. (2008). Berger JS (ed.). "A randomised controlled trial of triple antiplatelet therapy (aspirin, clopidogrel and dipyridamole) in the secondary prevention of stroke: safety, tolerability and feasibility". PLoS ONE. 3 (8): e2852. Bibcode:2008PLoSO...3.2852S. doi:10.1371/journal.pone.0002852. PMC 2481397. PMID 18682741.
- Gamboa A, Abraham R, Diedrich A, Shibao C, Paranjape SY, Farley G, et al. Role of adenosine and nitric oxide on the mechanisms of action of dipyridamole. Stroke. 2005;36(10):2170-2175.
- AAGBI Guidelines Neuraxial and Coagulation June 2016
- Carlock, Beth H.; Bienstock, Carol A.; Rogosnitzky, Moshe (2014-03-25). "Pterygium: Nonsurgical Treatment Using Topical Dipyridamole – A Case Report". Case Reports in Ophthalmology. 5 (1): 98–103. doi:10.1159/000362113. ISSN 1663-2699. PMC 3995373. PMID 24761148.
- "Topical Dipyridamole for Treatment of Pterygium and Associated Dry Eye Symptoms: Analysis of User-Reported Outcomes". ResearchGate. Retrieved 2019-05-19.