The medical letter on drugs and therapeutics october 27 2014

The Medical Letter ® on Drugs and Therapeutics Objective Drug Reviews Since 1959 Volume 56 ISSUE ISSUE No 1433 1454 October 27, 2014 IN THIS ISSUE Antithrombotic Drugs p 103 Volume 56 Important Copyright Message FORWARDING OR COPYING IS A VIOLATION OF U.S AND INTERNATIONAL COPYRIGHT LAWS The Medical Letter, Inc publications are protected by U.S and international copyright laws Forwarding, copying or any distribution of this material is prohibited Sharing a password with a non-subscriber or otherwise making the contents of this site available to third parties is strictly prohibited By accessing and reading the attached content I agree to comply with U.S and international copyright laws and these terms and conditions of The Medical Letter, Inc For further information click: Subscriptions, Site Licenses, Reprints or call customer service at: 800-211-2769 Published by The Medical Letter, Inc • A Nonprofit Organization Revised 11/12/14: A paragraph on dipyridamole has been added to the first page (after aspirin) The Medical Letter publications are protected by US and international copyright laws Forwarding, copying or any other distribution of this material is strictly prohibited For further information call: 800-211-2769 The Medical Letter ® on Drugs and Therapeutics Objective Drug Reviews Since 1959 Volume 56 ISSUE ISSUE No October 27, 2014 Take CME exams IN THIS ISSUE 1433 1454 Antithrombotic Drugs Volume 56 Related article(s) since publication Antiplatelet drugs are the drugs of choice for prevention and treatment of arterial thrombosis Anticoagulants are the drugs of choice for prevention and treatment of venous thromboembolism and for prevention of cardioembolic events in patients with atrial fibrillation ANTIPLATELET DRUGS Antiplatelet drugs are used mainly for acute coronary syndrome (ACS), which includes unstable angina/ non-ST-elevation myocardial infarction (UA/NSTEMI), ST-elevation myocardial infarction (STEMI), and percutaneous coronary intervention (PCI) ASPIRIN — Aspirin acetylates cyclooxygenase-1, blocking thromboxane synthesis and inhibiting platelet activation and aggregation for the life of the platelet (up to 10 days) Aspirin prophylaxis reduces the incidence of myocardial infarction (MI) and/or death by 1525% in patients with UA/NSTEMI, STEMI, or ischemic stroke, and in those undergoing PCI or a coronary artery bypass graft (CABG).1,2 In one randomized trial in patients undergoing noncardiac surgery, use of aspirin did not reduce the rate of cardiovascular events, and it increased the incidence of major bleeding.3 Aspirin can cause asthma and other hypersensitivity reactions in aspirin-intolerant patients DIPYRIDAMOLE — A pyrimidopyrimidine derivative, dipyridamole (Persantine, and generics) inhibits platelet uptake of adenosine and blocks adenosine diphosphate (ADP)-induced platelet aggregation It is also available in combination with aspirin (Aggrenox, and generics) Dipyridamole can cause severe headache and diarrhea, which tend to resolve with continued use A randomized, controlled trial (ESPRIT) in 2739 patients who had experienced a transient ischemic attack (TIA) or minor stroke in the previous months found that a combination of extended-release dipyridamole (200 mg bid) and low-dose aspirin (30-325 mg per day) was more effective than aspirin alone in preventing a composite of vascular death, stroke, MI, or major bleeding (173 vs 216 events) However, more patients discontinued the combination (470 vs 184), mainly because of headache.3a The combination was not more effective than clopidogrel alone in preventing recurrent stroke.3b Recent guidelines recommend a combination of extended-release dipyridamole 200 mg and aspirin 25 mg twice daily after a TIA or stroke for prevention of future stroke.3c THIENOPYRIDINES — The thienopyridines ticlopidine (seldom used now because of its toxicity), clopidogrel (Plavix, and generics), and prasugrel (Effient) bind to P2Y12 ADP receptors on the platelet surface, inhibiting platelet aggregation for the life of the platelet (up to 10 days) Ticlopidine can cause skin reactions, cytopenias, and thrombotic thrombocytopenic purpura; it has largely been replaced by clopidogrel Clopidogrel is converted to its active form by CYP2C19 The delayed onset of action can be problematic in patients who require a rapid antithrombotic effect Whether patients who are poor metabolizers of clopidogrel have a higher incidence of cardiovascular events is controversial.4 Proton pump inhibitors, particularly omeprazole (Prilosec, and others) and esomeprazole (Nexium, and others), inhibit CYP2C19 and can interfere with activation of clopidogrel Patients taking clopidogrel who have a clinical indication for a proton pump inhibitor should probably take pantoprazole (Protonix, and generics), lansoprazole (Prevacid, and others), or dexlansoprazole (Dexilant) instead.5 103 Published by The Medical Letter, Inc • A Nonprofit Organization The Medical Letter ® October 27, 2014 Vol 56 (1454) Table Some Antiplatelet Drugs for Acute Coronary Syndrome Dosage Adjustment for Renal Impairment Antiplatelet Effect1 Cost2 75-81 mg PO once/d CrCl