Aspirin, clopidogrel... Learn about 5 commonly used antiplatelet drugs in this article

*For medical professionals to read and reference only here is a summary for you! Antiplatelet drugs are one of the main treatment drugs for ischemic cerebrovascular disease, which includes a wide variety of commonly used clinically aspirin, clopidogrel, ticagrelor, cilostazol, dipyridamole, etc.
Antiplatelet drugs, do you really use them? Let's take a look at the mechanism of action, recommended dosage and precautions of these commonly used clinical antiplatelet drugs
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01 Aspirin▌ The mechanism of action inhibits cyclooxygenase (COX), reduces the production of thromboxane A2, thereby reducing platelet aggregation and producing antithrombotic effects
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▌ Recommended dose The American College of Chest Physicians (ACCP) guideline recommends a dose of 75-100 mg/d for secondary stroke prevention; the American Heart Association/American Stroke Association (AHA/ASA) guideline recommends a dose of 50-325 mg/day d
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▌ Adverse reactions Gastrointestinal toxicity (the most common gastrointestinal bleeding), Reye syndrome, effects on pregnancy and renal function, allergic reactions
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▌ Definition of aspirin resistance: refers to the reduced bioavailability of aspirin (such as poor adherence to treatment, decreased absorption, insufficient dosage, and drug interactions), genetic variability (more genes for COX-1, COX-2, and thromboxane A2 synthase).
non-response or decreased response to aspirin, as well as other possible mechanisms (eg, increased platelet turnover due to inflammation, infection, surgery, or stress)
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Treatment: First, determine whether the patient's compliance is due to subjective reasons such as insufficient dosage; after excluding this point, consider whether it is due to drug interaction and adjust the drug; finally, consider the patient's genetic variability, and choose a more appropriate drug.
Appropriate other antiplatelet drugs are used for treatment, and the commonly used drug is clopidogrel
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02Clopidogrel▌ Mechanism of action: It inhibits adenosine diphosphate (ADP)-dependent platelet aggregation, thereby playing an antithrombotic effect
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▌ The recommended dose of monotherapy for secondary stroke prevention is 75 mg/d
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▌ Adverse reactions Clopidogrel bleeding has better side effects than aspirin, but the incidence of rash and diarrhea is slightly higher
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▌ Definition of clopidogrel resistance: Gene polymorphisms of liver enzymes involved in the metabolism of clopidogrel (such as CYP1A2, CYP3A4 or CYP2C19) or gene polymorphisms of platelet P2Y12 receptors affect the ability of clopidogrel to inhibit platelet aggregation, resulting in patients being sensitive to clopidogrel.
No response or decreased response to pidogrel
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Treatment: First, determine the patient's compliance.
If it is clopidogrel resistance caused by objective reasons, it is recommended to switch to ticagrelor or cilostazol for treatment
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03 Ticagrelor▌ Mechanism of action Reversible binding to P2Y12 inhibitors, thereby inhibiting platelet aggregation
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▌ The recommended dose is to start treatment with a loading dose of 180 mg, then continue with 90 mg twice daily
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▌ Adverse reactions A few patients have dyspnea, bradycardia, etc.
or increased uric acid
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04Cilostazol▌ Mechanism of action: Phosphodiesterase 3 inhibitor, can increase the amount of cyclic adenosine monophosphate, reversibly inhibit platelet aggregation and intracranial vasodilation
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▌ The recommended dose for secondary stroke prevention is 100 mg twice a day
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▌ Adverse reactions In the adverse reaction study comparing cilostazol and aspirin, it was found that cilostazol is more prone to headache, diarrhea, palpitations, dizziness and tachycardia.
Other potential adverse reactions include diarrhea, infection and rhinitis, but The incidence is low
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05 The mechanism of action of dipyridamole is by inhibiting the activities of adenosine dehydrogenase and phosphodiesterase, resulting in the accumulation of adenosine, adenine nucleotides and cyclic adenosine monophosphate, thereby destroying platelet function.
Damo has vasodilatory properties
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▌ The sustained-release dosage form of dipyridamole at the recommended dose is often combined with aspirin to form a compound dosage form
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Aspirin - extended-release dipyridamole containing aspirin (25 mg) and extended-release dipyridamole (200 mg), 2 times a day
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Dipyridamole is also available in immediate-release dosage forms, with a usual dose of 50-100 mg three times a day
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▌ Adverse reactions Headache is the most common adverse reaction of aspirin-extended-release dipyridamole.
Other adverse reactions include abdominal pain, nausea, diarrhea and vomiting
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The following 4 points should be paid attention to in the application of antiplatelet drugs: 1.
Patients who are intolerant to antiplatelet drugs or have allergies due to gastrointestinal discomfort or allergies who cannot tolerate aspirin (including compound aspirin-sustained-release dipyridamole) are the first choice to use Clopidogrel treatment, if clopidogrel is not tolerated, cilostazol treatment can be selected
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2.
The data from randomized controlled trials in Asian population support the safety and efficacy of cilostazol for secondary stroke prevention in Asian population, which is different from other ethnic groups
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3.
Patients with indications for anticoagulation In patients with atrial fibrillation leading to ischemic stroke or TIA, due to the increased risk of bleeding, antiplatelet therapy is not performed, but anticoagulation therapy is used
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However, cryptogenic stroke, including embolic stroke of unknown cause (ESUS), is usually not an indication for anticoagulation, and antiplatelet therapy is most preferred
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4.
Prevention of gastroduodenal toxicity For patients with increased risk of gastroduodenal toxicity caused by antiplatelet drugs, especially those aged ≥75 years, proton pump inhibitors can be used concurrently
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References: [1] Lansberg MG, O'Donnell MJ, Khatri P, et al.
Antithrombotic and thrombolytic therapy for ischemic stroke: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.
Chest 2012;141:e601S.
[2]Greving JP,Diener HC,Reitsma JB,et al.
Antiplatelet Therapy After Noncardioembolic Stroke.
Stroke 2019;50:1812.
[3]Chinese expert consensus on antiplatelet therapy[J].
Zhonghuaxin Journal of Vascular Diseases, 2013(03): 183-19 [4] Huo Yong, Wang Yongjun, Gu Yongquan, etc.
Expert consensus on diagnosis and treatment of people with intolerance and low response to commonly used oral antiplatelet drugs [J].
Chinese Journal of Interventional Cardiology.
2021,29(05):240-249.
[5]van der Meijden PEJ,Heemskerk JWM.
Platelet biology and functions:new concepts and clinical perspectives[J].
Nat Rev Cardiol,2019,16(3):166-179 .
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