Dipyridamole

Dipyridamole capsule is indicated in-

• Secondary prevention of ischaemic stroke and transient ischaemic attacks either alone or in conjunction with aspirin.
• An adjunct to oral anti-coagulation for prophylaxis of thromboembolism associated with prosthetic heart valves.

Dipyridamole likely inhibits both adenosine deaminase and phosphodiesterase, preventing the degradation of cAMP, an inhibitor of platelet function. This elevation in cAMP blocks the release of arachidonic acid from membrane phospholipids and reduces thromboxane A2 activity. Dipyridamole also directly stimulates the release of prostacyclin, which induces adenylate cyclase activity, thereby raising the intraplatelet concentration of cAMP and further inhibiting platelet aggregation.

Adults including the elderly: The recommended dose is 200 mg capsule twice daily, usually one in the morning and one in the evening preferably with meals. The capsules should be swallowed whole without chewing.

Children: Dipyridamole 200 mg capsule is not recommended for children.

Dipyridamole increases the plasma levels and cardiovascular effects of adenosine. Adjustment of adenosine dosage should therefore be considered if use with dipyridamole is unavoidable. There is evidence that the effects of acetylsalicylic acid and dipyridamole on platelet behaviour are additive. When dipyridamole is used in combination with anticoagulants or acetylsalicylic acid, the statements on intolerance and risks for these preparations must be observed. Addition of dipyridamole to acetylsalicylic acid does not increase the incidence of bleeding events. When dipyridamole was administered concomitantly with warfarin, bleeding was no greater in frequency or severity than that observed when warfarin was administered alone. Dipyridamole may increase the hypotensive effect of blood pressure lowering drugs and may counteract the anticholinesterase effect of cholinesterase inhibitors thereby potentially aggravating myasthenia gravis.

Hypersensitivity to any component of the product. Warnings and precautions: Among other properties, dipyridamole acts as a potent vasodilator. It should therefore be used with caution in patients with severe coronary artery disease including unstable angina and/or recent myocardial infarction, left ventricular outflow obstruction or haemodynamic instability (e.g. decompensated heart failure). Patients being treated with regular oral doses of Dipyridamole MR should not receive additional intravenous dipyridamole. Clinical experience suggests that patients being treated with oral dipyridamole who also require pharmacological stress testing with intravenous dipyridamole, should discontinue drugs containing oral dipyridamole for twenty-four hours prior to stress testing. In patients with myasthenia gravis readjustment of therapy may be necessary after changes in dipyridamole dosage. Dipyridamole should be used with caution in patients with coagulation disorders.

The following side effects have been reported, Blood and lymphatic system disorders- Thrombocytopenia; Immune system disorders- Hypersensitivity, Angioedema; Nervous system disorders- Headache, Dizziness; Cardiac disorders- Angina pectoris, Tachycardia; Vascular disorders- Hypotension, Hot flush; Respiratory, thoracic and mediastinal disorders- Bronchospasm; Gastrointestinal disorders- Diarrhoea, Nausea, Vomiting; Skin and subcutaneous tissue disorders- Rash, Urticaria; Musculoskeletal, connective tissue and bone disorders- Myalgia, Injury, poisoning and procedural complications- post procedural haemorrhage, operative haemorrhage.

There is inadequate evidence of safety in human pregnancy, but dipyridamole has been used for many years without apparent ill-consequence. Animal studies have shown no hazard. 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 MR should only be used during lactation if considered essential by the physician.

In patients with rapidly worsening angina, subvalvular aortic stenosis, haemodynamic instability associated with recent MI or coagulation disorders esp when given IV during myocardial imaging. Hypotension, unstable angina, aortic stenosis. Pregnancy and lactation. Safety and efficacy are not established in childn < 12 yrs.

Due to the low number of observations, experience with dipyridamole overdose is limited. Symptoms such as feeling warm, flushes, sweating, accelerated pulse, restlessness, feeling of weakness, dizziness, drop in blood pressure and anginal complaints can be expected.

Anti-platelet drugs

Keep below 30°C temperature, away from light & moisture. Keep out of the reach of children.