Dipyridamole

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Dipyridamole
Systematic (IUPAC) name
2-{[9-(bis(2-hydroxyethyl)amino)-2,7-bis(1-piperidyl)- 3,5,8,10-tetrazabicyclo[4.4.0]deca-2,4,7,9,11-pentaen- 4-yl]-(2-hydroxyethyl)amino}ethanol
Identifiers
CAS number	58-32-2
ATC code	B01AC07
PubChem	3108
DrugBank	APRD00360
Chemical data
Formula	C24H40N8O4
Mol. weight	504.626 g/mol
Pharmacokinetic data
Bioavailability	?
Protein binding	99%
Metabolism	?
Half life	40 minutes
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status
Routes	?

Dipyridamole is a drug that inhibits platelet aggregation and causes vasodilation.

• It inhibits the cellular reuptake of adenosine into platelets, red blood cells and endothelial cells leading to increased extracellular concentrations of adenosine.
• It also inhibits the enzyme adenosine deaminase which normally breaks down adenosine into inosine. This inhibition leads to further increased levels of extracellular adenosine.
• Dipyridamole also inhibits the enzyme phosphodiesterase which normally breaks down cAMP.
• Adenosine interacts with the adenosine receptors to cause increased cAMP via adenylate cyclase.
• cAMP impairs platelet aggregation and also causes arteriolar smooth muscle relaxation.

Modified release dipyridamole is used in conjunction with aspirin (under the trade name Aggrenox®) in the secondary prevention of stroke and transient ischemic attack. This practice is now confirmed by the ESPRIT trial.

Dipyridamole is also used in nuclear cardiac stress testing as a coronary vasodilator.

• Via the mechanisms mentioned above, it increases the local concentration of adenosine in the coronary circulation which causes vasodilation.
• Vasodilation of healthy arteries is physiologic, whereas diseased arteries actually experience a drop in blood flow via "steal" phenomena which can be detected by electrocardiogram and echocardiography when it causes ischemia.
• Flow heterogeneity (a necessary precursor to ischemia) can de detected with gamma-cameras and SPECT using nuclear imaging agents such as Thallium-201 and Tc99m-Sestamibi.

Antithrombotics (thrombolytics, anticoagulants, and antiplatelet drugs) (B01) edit
Vitamin K antagonists:	Acenocoumarol, Clorindione, Dicumarol (Dicoumarol}, Diphenadione, Ethyl biscoumacetate, Phenprocoumon, Phenindione, Tioclomarol, Warfarin
Heparin group (Platelet aggregation inhibitors):	Antithrombin III, Bemiparin, Dalteparin, Danaparoid, Enoxaparin, Heparin, Nadroparin, Parnaparin, Reviparin, Sulodexide, Tinzaparin
Other Platelet aggregation inhibitors:	Abciximab, Acetylsalicylic acid (Aspirin), Aloxiprin, Beraprost, Ditazole, Carbasalate calcium, Cloricromen, Clopidogrel, Dipyridamole, Epoprostenol, Eptifibatide, Indobufen, Iloprost, Picotamide, Prasugrel, Ticlopidine, Tirofiban, Treprostinil, Triflusal
Enzymes:	Alteplase, Ancrod, Anistreplase, Brinase, Drotrecogin alfa, Fibrinolysin, Protein C, Reteplase, Saruplase, Streptokinase, Tenecteplase, Urokinase
Direct thrombin inhibitors:	Argatroban, Bivalirudin, Dabigatran, Desirudin, Hirudin, Lepirudin, Melagatran, Ximelagatran
Other antithrombotics:	Dabigatran, Defibrotide, Dermatan sulfate, Fondaparinux, Rivaroxaban
Non-medicinal:	Citrate, EDTA, Oxalate