Dipyridamole (dipyridamole)

The usual adult oral dosage of dipyridamole for adjunctive use with coumarin anticoagulant (e.g., warfarin) therapy in the prevention of postoperative thromboembolic complications of cardiac valve replacement is 75-100 mg 4 times daily.

For the prevention of thromboembolic complications in patients with various other thromboembolic disorders+, oral dosage of dipyridamole generally has ranged from 150-400 mg daily, in combination with another platelet-aggregation inhibitor (e.g., aspirin) or warfarin.

For reducing the risk of stroke in patients who have had transient ischemic attacks (TIAs) or completed stroke caused by thrombosis, the usual dosage of oral extended-release dipyridamole is 200 mg in fixed combination with aspirin 25 mg (1 capsule) twice daily in the morning and evening. If headaches become intolerable during initial treatment, the dosage of the dipyridamole/aspirin fixed combination should be reduced to 200 mg of dipyridamole and 25 mg of aspirin (1 capsule) once daily at bedtime and low-dose aspirin should be administered in the morning. Because no outcome data are available with this regimen and headaches diminish during continued treatment, patients should resume the usual regimen (200 mg of extended-release dipyridamole and 25 mg of aspirin twice daily) as soon as possible (usually within 1 week). The amount of aspirin in the fixed-combination preparation may not be adequate to prevent recurrent myocardial infarction (MI) or angina pectoris in patients with stroke or TIA.

When used as an adjunct to thallium myocardial imaging, dipyridamole usually is administered as a single IV dose of 0.57 mg/kg, infused at a rate of 0.142 mg/kg per minute for 4 minutes. Although the maximum tolerated IV dose of dipyridamole has not been determined, clinical experience suggests that a total dose exceeding 60 mg is not needed for any patient. Thallium-201 should be injected within 5 minutes following completion of the dipyridamole infusion.

Dipyridamole is administered orally or IV. Capsules containing the fixed-combination of extended-release dipyridamole and aspirin should be swallowed whole and should not be chewed. The fixed-combination capsules containing extended-release dipyridamole and aspirin may be administered without regard to food.

Prior to IV administration, dipyridamole injection should be diluted in at least twice the injection volume with 0.45% sodium chloride injection, 0.9% sodium chloride injection, or 5% dextrose injection to a final volume of approximately 20-50 mL. Infusion of undiluted dipyridamole may cause local irritation.

No dosing information is available for this tab.

No dosing information is available for this tab.

Since dipyridamole may inhibit platelet aggregation, heparin and dipyridamole should be used concomitantly with caution and patients should be monitored closely to prevent bleeding; however, the actual incidence of this reaction has not been established.

In a dosage of 400 mg daily, dipyridamole does not affect prothrombin time and can be administered with warfarin. Concomitant use of dipyridamole and warfarin does not appear to increase the frequency or severity of bleeding compared with use of warfarin alone. However, in rare instances, increased bleeding during or after surgery has been observed during such concurrent therapy. Some clinicians recommend maintenance of prothrombin time in the lower end of the therapeutic range during concomitant administration of these drugs to avoid possible bleeding.

Dipyridamole may increase the plasma concentrations and the cardiovascular effects of adenosine; adjustment of adenosine dosage may be necessary. Methylxanthines are competitive adenosine receptor antagonists, and aminophylline has been used effectively to terminate persistent adverse effects of dipyridamole. Use of other xanthine derivatives (e.g., caffeine) or maintenance dosages of oral theophylline may abolish the coronary vasodilation of dipyridamole and lead to false negative thallium imaging results. (See Pharmacology.)

In patients receiving an anticholinesterase agent for the treatment of myasthenia gravis, concomitant use of dipyridamole may counteract the anticholinesterase effects of such inhibitors and potentially aggravate myasthenia gravis.

There are no contraindication interactions for this drug.

There are no severe interactions for this drug.

There are no moderate interactions for this drug.

There is no enhanced messaging for this drug.

There are no contraindication contraindications for this drug.

There are no severe contraindications for this drug.

There are no moderate contraindications for this drug.

There is no enhanced messaging for this drug.

There are no severe adverse reactions for this drug.

There are no less severe adverse reactions for this drug.

No enhanced messaging available.

No enhanced messaging available.

Safe use of dipyridamole during pregnancy has not been established. Reproduction studies in mice receiving dipyridamole dosages up to 125 mg/kg daily (1.5 times the maximum recommended daily human oral dosage on a mg/m2 basis), rats receiving dosages not exceeding 1000 mg/kg daily (25 times the maximum recommended daily human oral dosage on a mg/m2 basis), and rabbits receiving dosages not exceeding 40 mg/kg daily (2 times the maximum recommended daily human oral dosage on a mg/m2 basis) have not revealed evidence of harm to the fetus. There are no adequate and controlled studies to date using dipyridamole in pregnant women, and the drug should be used during pregnancy only when clearly needed. Extended-release dipyridamole in fixed combination with aspirin should be avoided in the third trimester of pregnancy and during labor and delivery because of the aspirin component of this preparation; aspirin has been shown to be teratogenic in animals and to cause fetal harm when administered to a pregnant woman. If dipyridamole in fixed combination with aspirin is used during pregnancy or the patient becomes pregnant while taking the fixed combination, the patient should be apprised of the potential hazard to the fetus. (See Cautions: Pregnancy, Fertility, and Lactation, in the Salicylates General Statement 28:08.04.24.)

Because dipyridamole is distributed into milk, the drug should be used with caution in nursing women.

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