Dipyridamole

Intravenous
Myocardial imaging

Oral
Prophylaxis of thromboembolism following cardiac valve replacement

Oral
Secondary prophylaxis of ischaemic stroke, Secondary prophylaxis of transient ischaemic attack

Should be taken on an empty stomach. Take 1 hr before meals. May be taken w/ meals to reduce GI discomfort.

Intravenous: Dilute in at least 1:2 ratio w/ NaCl 0.9% or 0.45%, or dextrose 5% to make a total volume of approx 20-50 mL.

Patient w/ hypotension, severe coronary artery disease including unstable angina or recent MI, aortic stenosis, decompensated heart failure, coagulation disorder, migraine, myasthenia gravis. Pregnancy and lactation.

Nervous: Headache, dizziness, faintness, seizure.
CV: Hypotension, angina, tachycardia.
GI: Nausea, diarrhoea, vomiting.
Resp: Bronchospasm.
Haematologic: Thrombocytopenia.
Musculoskeletal: Myalgia.
Dermatologic: Rash, urticaria, facial flushing, angioedema.
Potentially Fatal: Cardiac death, MI, ventricular fibrillation, asystole, sinus node arrest, symptomatic ventricular tachycardia, stroke, transient cerebral ischemia (IV).

IV/Parenteral/PO: B

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

Monitor BP, heart rate, ECG, LFT, respiration.

Symptoms: Cardiac death, cardiac arrest, MI, chest pain, angina pectoris, ECG changes, syncope, cerebrovascular events, headache, myalgia, paraesthesia, warm feeling, flushes, sweating, restlessness, weakness, dizziness, hypotension, and tachycardia. Management: Symptomatic treatment. Perform gastric lavage. Administer xanthine derivatives (e.g. aminophylline 75-100 mg) to reverse haemodynamic effects.

May increase plasma concentration and CV effects of adenosine. Enhances effects of oral anticoagulants and produces additive effects w/ other anti-platelets (e.g. aspirin). May increase hypotensive effect of BP lowering drugs. May counteract anticholinesterase effect and aggravate myasthenia gravis when used w/ cholinesterase inhibitors. May reduce the efficacy of fludarabine. Reduced absorption w/ antacids. Abolished coronary vasodilation w/ xanthine derivatives (e.g. theophylline, aminophylline, caffeine) during myocardial imaging.

Description:
Mechanism of Action: Dipyridamole, a platelet aggregation inhibitor, causes an accumulation of adenosine, adenine nucleotides, and cyclic AMP by inhibiting the activity of adenosine deaminase and phosphodiesterase, thus inhibiting platelet aggregation and producing vasodilation. Addtionally, it stimulates the release of prostacyclin or PGD₂ and causes coronary vasodilation.
Pharmacokinetics:
Absorption: Incompletely absorbed from the GI tract. Time to peak plasma concentrations: Approx 75 min.
Distribution: Widely distributed into body tissues. Crosses the placenta in small amounts and enters breast milk. Volume of distribution: 2-3 L/kg. Plasma protein binding: 91-99%, mainly to α₁-acid glycoprotein.
Metabolism: Metabolised in the liver to glucuronide conjugate; may undergo enterohepatic recirculation.
Excretion: Via faeces (as glucuronide conjugates and unchanged drug). Terminal elimination half-life: 10-12 hr.

Source: National Center for Biotechnology Information. PubChem Database. Dipyridamole, CID=3108, https://pubchem.ncbi.nlm.nih.gov/compound/Dipyridamole (accessed on Jan. 21, 2020)

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

Anticoagulants, Antiplatelets & Fibrinolytics (Thrombolytics)

Anon. Dipyridamole. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 07/11/2016.

Buckingham R (ed). Dipyridamole. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 07/11/2016.

Dipyridamole Injection, Solution (Hospira, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 07/11/2016.

Dipyridamole Tablet, Film Coated (Teva Pharmaceuticals USA, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 07/11/2016.

Joint Formulary Committee. Dipyridamole. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 07/11/2016.

McEvoy GK, Snow EK, Miller J et al (eds). Dipyridamole. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 07/11/2016.