Dipyridamole

Dipyridamole May be taken with or without food. ER cap: Swallow whole & do not chew.

Solution for IV infusion: Dilute in at least 1:2 ratio with NaCl 0.9%, NaCl 0.45%, or dextrose 5% in water to make a total volume of approx 20-50 mL.

Patient with hypotension; severe coronary artery disease, including unstable angina, recent MI, left ventricular outflow obstruction, and decompensated heart failure; abnormalities of cardiac impulse conduction or formation; coagulation disorders, asthma, myasthenia gravis. Interrupt oral dipyridamole therapy for 24-48 hours before undergoing pharmacological stress testing with IV dipyridamole or other adenosinergic agents (e.g. adenosine, regadenoson). Hepatic impairment. Pregnancy and lactation.

Significant: Angina pectoris, bronchospasm, hypotension.
Blood and lymphatic system disorders: Thrombocytopenia.
Gastrointestinal disorders: Nausea, vomiting, diarrhoea, abdominal distress.
Immune system disorders: Hypersensitivity reactions, including angioedema.
Injury, poisoning and procedural complications: Post-procedural haemorrhage, operative haemorrhage.
Investigations: Elevated hepatic enzymes, ECG changes.
Musculoskeletal and connective tissue disorders: Myalgia.
Nervous system disorders: Headache, dizziness.
Skin and subcutaneous tissue disorders: Urticaria, rash.
Vascular disorders: Flushing, syncope.
Potentially Fatal: MI, ventricular fibrillation, asystole, sinus node arrest, symptomatic ventricular tachycardia, stroke, transient cerebral ischaemia and seizures (particularly for IV doses).

IV/Parenteral: B; PO: Z (Some manufacturers do not recommend use during pregnancy unless benefits outweigh potential risks while others recommend it should only be used during pregnancy when clinically required.)

This drug may cause dizziness, if affected, do not drive or operate machinery.

Monitor blood pressure regularly, including heart rate, ECG and respiration (particularly when used during myocardial imaging). Assess for signs of poor perfusion (e.g. pallor, cyanosis, cold or clammy skin).

Symptoms: Warm feeling, flushing, sweating, restlessness, weakness, dizziness, anginal complaints, hypotension, and tachycardia.

Management: Symptomatic and supportive treatment. Performing gastric lavage may be considered. May administer xanthine derivatives (e.g. aminophylline) to reverse the haemodynamic effects of dipyridamole. Monitor ECG continuously.

Concomitant use with xanthine derivatives (e.g. theophylline, caffeine) may reduce the coronary vasodilating effects of dipyridamole. May increase the plasma levels and CV effects of adenosine. May increase the adenosine-mediated effects of regadenoson. May enhance the hypotensive effect of blood pressure-lowering drugs. May counteract the anticholinesterase effect of cholinesterase inhibitors which may aggravate myasthenia gravis. Enhances the efficacy of oral anticoagulants. Additive effects with antiplatelet agents (e.g. aspirin). May reduce absorption with antacids.

When used as adjunct to thallium-201 for myocardial imaging: May lead to false-negative results if given concurrently with caffeine or theophylline.

Description:
Overview: Dipyridamole is a non-nitrate vasodilator with antiplatelet activity.
Mechanism of Action: The exact mechanism of action has not been fully elucidated; however, dipyridamole appears to inhibit adenosine deaminase and phosphodiesterase activity, leading to the accumulation of adenosine, adenine nucleotides, and cyclic adenosine monophosphate (cAMP). These mediators consequently inhibit platelet aggregation and cause coronary vasodilation. It may also stimulate the synthesis and release of prostacyclin or prostaglandin D₂ from endothelial cells, thereby further inhibiting platelet aggregation. In myocardial imaging to aid thallium-201, dipyridamole presumably induces vasodilation through a "coronary steal" phenomenon in which intact coronary arteries dilate and sustain enhanced blood flow while shunting the blood away from stenotic coronary arteries.
Pharmacodynamics: In combination with warfarin, dipyridamole has been shown to prolong platelet survival in patients with valvular heart disease and to maintain platelet count in those undergoing open-heart surgery. It does not reduce cardiac work and myocardial consumption remains unchanged. IV administration of dipyridamole moderately decreases blood pressure and increases heart rate and cardiac output in response to the vasodilatory effect. However, usual oral doses generally do not produce changes in blood pressure or peripheral blood flow.
Pharmacokinetics:
Absorption: Incompletely absorbed from the gastrointestinal tract. Time to peak plasma concentration: 75 minutes (conventional tab or sugar-coated tab); approx 2-3 hours (modified-release cap).
Distribution: Enters breast milk. Volume of distribution: 2-3 L/kg. Plasma protein binding: 91-99%, mainly to α₁-acid glycoprotein and albumin.
Metabolism: Metabolised in the liver to form glucuronide conjugates. May undergo enterohepatic recirculation.
Excretion: Via faeces (as glucuronide conjugates and unchanged drug). Terminal elimination half-life: 10-12 hours.

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 3108, Dipyridamole. https://pubchem.ncbi.nlm.nih.gov/compound/Dipyridamole. Accessed Oct. 27, 2025.

Oral:
Store between 20-25°C. Protect from light and moisture.

Intravenous:
Store between 15-25°C. Do not freeze. Protect from light.

Anticoagulants, Antiplatelets & Fibrinolytics (Thrombolytics)

B01AC07 - dipyridamole ; Belongs to the class of platelet aggregation inhibitors excluding heparin. Used in the treatment of thrombosis.

Brayfield A, Cadart C (eds). Dipyridamole. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 07/10/2025.

Dipyridamole 200 mg/5 mL Oral Suspension (Syri Limited). MHRA. https://products.mhra.gov.uk. Accessed 07/10/2025.

Dipyridamole Injection (Hikma Pharmaceuticals USA Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 07/10/2025.

Dipyridamole Tablet (Amneal Pharmaceuticals of New York LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 07/10/2025.

Dipyridamole Tablets 100 mg (Genethics Europe Limited). MHRA. https://products.mhra.gov.uk. Accessed 07/10/2025.

Dipyridamole. Gold Standard Drug Database in ClinicalKey [online]. Elsevier Inc. https://www.clinicalkey.com. Accessed 20/10/2025.

Dipyridamole. UpToDate Lexidrug, AHFS DI (Adult and Pediatric) Online. American Society of Health-System Pharmacists, Inc. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 07/10/2025.

Dipyridamole. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 07/10/2025.

Douglas Pharmaceuticals Ltd. Pytazen SR Modified Release Tablet 150 mg data sheet 10 July 2024. Medsafe. http://www.medsafe.govt.nz. Accessed 07/10/2025.

Jenapri PR 200 mg Prolonged-release Capsules, Hard (Mercury Pharmaceuticals Ltd). MHRA. https://products.mhra.gov.uk. Accessed 07/10/2025.

Joint Formulary Committee. Dipyridamole. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 07/10/2025.