Dipyridamole

Dipyridamole has some antimuscarinic effects. Additive antimuscarinic effects, both peripheral and central, can develop if two or more drugs with antimuscarinic properties are used together.

The absorption of dipyridamole may be reduced by drugs such as antacids that increase gastric pH.

Dipyridamole may enhance the effects of oral anticoagulants due to its antiplatelet effect. When dipyridamole is used in combination with anticoagulants and aspirin the statements on intolerance and risks for these preparations must be observed.

The combination of dipyridamole and coumarin anticoagulants does not alter the prothrombin time, but might cause an increased risk of serious bleeding when compared with anticoagulants alone.

Dipyridamole may increase the hypotensive effects of drugs which reduce blood pressure.

Dipyridamole may counteract the anticholinesterase effects of cholinesterase inhibitors thereby potentially aggravating myasthenia gravis.

Dipyridamole inhibits the reuptake of adenosine and may enhance its effects; the dose of adenosine must be reduced if both drugs are given concomitantly.

There is an increased risk of bleeding when clopidogrel is given with dipyridamole.

Dipyridamole may cause a minor increase in the absorption of digoxin.

Dipyridamole may also inhibit the uptake of fludarabine and may reduce its efficacy.

Dipyridamole is a potent vasodilator. It should be used with caution in patients with sub-valvular aortic stenosis, hypotension, severe coronary artery disease including unstable angina or haemodynamic instability associated with recent myocardial infarction, left ventricular outflow obstruction such as aortic stenosis, and in patients with decompensated heart failure.

Dipyridamole should be used with caution in patients with coagulation disorders.

Oral dipyridamole should be stopped 24 hours before intravenous use for stress testing.

In patients with myasthenia gravis readjustment of therapy may be necessary after changes in dipyridamole dosage.

There is inadequate evidence of safety in human pregnancy, but dipyridamole has been used for many years without apparent ill-consequence. Dipyridamole should only be administrated if clearly needed. Data from the use of dipyridamole in pregnancy are inadequate. Animal studies have shown no hazard of fetal harm. Nevertheless, medicines should not be used in pregnancy, especially the first trimester unless the expected benefit is thought to outweigh the possible risk to the foetus.

Dipyridamole is excreted in breast milk (at levels about 6% of plasma concentration), and therefore there is a risk of affecting the breast-feeding infant. Dipyridamole should only be used during breast-feeding if considered essential by the physician.

Fertility

No studies on the effect on human fertility have been conducted with dipyridamole. Non-clinical studies with dipyridamole did not indicate direct or indirect harmful effects with respect to fertility.

No studies on the effects on the ability to drive and use machines have been performed. However, patients should be advised that they may experience undesirable effects such as dizziness during treatment with dipyridamole. If patients experience dizziness they should avoid potentially hazardous tasks such as driving or operating machinery.