An antiplatelet drug (antiaggregant), also known as a platelet agglutination inhibitor or platelet aggregation inhibitor, is a member of a class of pharmaceuticals that decrease platelet aggregation [1] and inhibit thrombus formation. They are effective in the arterial circulation where classical Vitamin K antagonist anticoagulants have minimal effect. [2]
Antiplatelet drugs are widely used in primary and secondary prevention of thrombotic disease, especially myocardial infarction and ischemic stroke. [1]
Antiplatelet therapy with one or more of these drugs decreases the ability of blood clots to form by interfering with the platelet activation process in primary hemostasis. Antiplatelet drugs can reversibly or irreversibly inhibit the process involved in platelet activation resulting in decreased tendency of platelets to adhere to one another and to damaged blood vessels' endothelium. [3]
Antiplatelet medications are one of the primary recommendations for treatment of both stable [4] and unstable [5] ischemic heart disease. Most commonly, aspirin is used as a single medication in cases of uncomplicated stable angina, and in some cases of unstable angina. If a patient does not tolerate aspirin, ADP/P2Y inhibitors may be used as single-drug therapy instead. More severe and complicated cases are treated with dual antiplatelet therapy, or in some cases triple therapy that includes direct oral anticoagulants. [6] Clinicians must make a choice that balances patient risk with the increased risks of bleeding associated with combination therapy. [4] [5]
Often a combination of aspirin plus an ADP/P2Y inhibitor [7] (such as clopidogrel, prasugrel, ticagrelor, or another) is used to obtain greater effectiveness than with either agent alone. This is known as "dual antiplatelet therapy" (or DAPT). DAPT is used in patients who have, or are at high risk of developing, unstable angina, NSTEMI myocardial infarctions, and other high-risk thrombotic conditions. [5] Dual antiplatelet therapy has been found to significantly reduce rates of heart attacks, strokes, and overall cardiovascular death, but is not used in low-risk patients because it significantly increases the risks of major bleeding. [8]
Classes of antiplatelet drugs include:
Prevention and treatment of arterial thrombosis is essential in patients with certain medical conditions whereby the risk of thrombosis or thromboembolism may result in disastrous consequences such as heart attack, pulmonary embolism or stroke. [3] Patients who require the use of antiplatelet drugs are: stroke with or without atrial fibrillation, any heart surgery (especially prosthetic replacement heart valve), Coronary Heart Disease such as stable angina, unstable angina and heart attack, patients with coronary stent, Peripheral Vascular Disease/Peripheral Arterial Disease and apical/ventricular/mural thrombus. [3]
Treatment of established arterial thrombosis includes the use of antiplatelet drugs and thrombolytic therapy. Antiplatelet drugs alter the platelet activation at the site of vascular damage crucial to the development of arterial thrombosis.
Antiplatelet therapy may increase the risk of a bleed during surgery, however, stopping therapy may increase the risk of other thrombotic problems including myocardial infarction. [9] When considering these medications and the risk-benefit ratio in the perioperative period, one must consider the risk of stopping the medication and a clot forming versus the risk of bleeding during or after the surgery if medication is continued. [10] A 2018 Cochrane Review that included five randomized controlled trials found low-certainty evidence to suggest that continuing or discontinuing antiplatelet therapy for a non-cardiac surgery does not make a difference in mortality, major bleeds that require surgery, or ischaemic events. [9] The same review found moderate certainty evidence that continuing or discontinuing therapy also did not have a big difference on the incidence of bleeds requiring a blood transfusion. [9]
Dentists should be aware of the risk of prolonged bleeding time in patients taking antiplatelet drugs when planning dental treatments that are likely to cause bleeding. Therefore, it is important for dentists to know how to assess patient's bleeding risk and how to manage them. [3]
Identify the likelihood and risk of dental treatment causing bleeding complications. [3]
Dental procedures unlikely to cause bleeding | Dental procedures with low risk of post-operative bleeding complications | Dental procedures with high risk of post-operative bleeding complications |
---|---|---|
Local anaesthesia using aspirating syringe and vasoconstrictor | Simple extractions up to 3 teeth with restricted wound size | Extractions involving surgery, large wound or more than 3 teeth at once |
Basic Periodontal examination (BPE) | Incision and drainage of intra-oral swellings | Flap raising procedures |
Supragingival plaque, calculus, stain removal | Six point full periodontal examination | Gingival recontouring |
Direct or indirect restoration with supragingival margins | Root surface debridement and subgingival scaling | Biopsies |
Orthograde endodontics | Direct or indirect restorations with subgingival margins | |
Prosthetic procedures | ||
Fitting and adjustment of orthodontic appliances. |
Antiplatelet drugs effect may be affected by patient's medications, current medical conditions, food and supplements taken. Antiplatelet drugs effect may be increased or decreased. An increase in antiplatelet effect would increase the risk of bleeding and could cause prolonged or excessive bleeding. A decrease in antiplatelet effect would reduce the risk of bleeding, but increase the thromboembolic risk. [3] Drug toxicity may increase when multiple antiplatelet drugs are used. Gastrointestinal bleeding is a common adverse event seen in many patients. [11]
Medications that may increase antiplatelet drug effect: [3]
Medications that may decrease antiplatelet drug effect: [3]
Use of NSAIDs as part of dental management of patients with vascular disease should be discouraged as NSAIDs have antiplatelet effect. Instead, simple analgesics such as paracetamol or co-codamol should be of first choice. If NSAIDs are required, the risk of bleeding increases with duration of dental treatment. [3]
Medical conditions that may increase antiplatelet drugs' effect include: [3]
Chronic kidney failure, liver disease, haematological malignancy, recent or current chemotherapy, advanced heart failure, mild forms of inherited bleeding disorders (e.g. haemophilia, Von Willebrand's disease) and idiopathic thrombocytopenic purpura.
Food and supplements that may increase antiplatelet drugs' effect: [3]
St. John's wort, ginkgo biloba, garlic.
Oral Antiplatelet Drugs | UK Trade Name | Other Names (Non-UK) |
---|---|---|
Aspirin | Nu-Seals, Microprin, caprin Dual with dipyridamole: Asasantin Retard, Molita Modified Release | acetylsalicylic acid - There are numerous brand names for Aspirin |
Clopidogrel | Plavix, Grepid | Iscover |
Dipyridamole | Persantin, Persantin Retard, Attia Modified Release, Ofcram PR. Dual with aspirin: Asasantin Retard, Molita Modified Release | |
Prasugrel | Efient | Effient, Prasita |
Ticagrelor | Brilique | Brilinta, Possia |
Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and/or inflammation, and as an antithrombotic. Specific inflammatory conditions which aspirin is used to treat include Kawasaki disease, pericarditis, and rheumatic fever.
Angina, also known as angina pectoris, is chest pain or pressure, usually caused by insufficient blood flow to the heart muscle (myocardium). It is most commonly a symptom of coronary artery disease.
An anticoagulant, commonly known as a blood thinner, is a chemical substance that prevents or reduces the coagulation of blood, prolonging the clotting time. Some occur naturally in blood-eating animals, such as leeches and mosquitoes, which help keep the bite area unclotted long enough for the animal to obtain blood.
Clopidogrel, sold under the brand name Plavix among others, is an antiplatelet medication used to reduce the risk of heart disease and stroke in those at high risk. It is also used together with aspirin in heart attacks and following the placement of a coronary artery stent. It is taken by mouth. Its effect starts about two hours after intake and lasts for five days.
Thromboxane is a member of the family of lipids known as eicosanoids. The two major thromboxanes are thromboxane A2 and thromboxane B2. The distinguishing feature of thromboxanes is a 6-membered ether-containing ring.
Ticlopidine, sold under the brand name Ticlid, is a medication used to reduce the risk of thrombotic strokes. It is an antiplatelet drug in the thienopyridine family which is an adenosine diphosphate (ADP) receptor inhibitor. Research initially showed that it was useful for preventing strokes and coronary stent occlusions. However, because of its rare but serious side effects of neutropenia and thrombotic microangiopathy it was primarily used in patients in whom aspirin was not tolerated, or in whom dual antiplatelet therapy was desirable. With the advent of newer and safer antiplatelet drugs such as clopidogrel and ticagrelor, its use remained limited.
Dipyridamole is a nucleoside transport inhibitor and a PDE3 inhibitor medication that inhibits blood clot formation when given chronically and causes blood vessel dilation when given at high doses over a short time.
Prasugrel, sold under the brand name Effient in the US, Australia and India, and Efient in the EU) is a medication used to prevent formation of blood clots. It is a platelet inhibitor and an irreversible antagonist of P2Y12 ADP receptors and is of the thienopyridine drug class. It was developed by Daiichi Sankyo Co. and produced by Ube and marketed in the United States in cooperation with Eli Lilly and Company.
Unstable angina is a type of angina pectoris that is irregular or more easily provoked. It is classified as a type of acute coronary syndrome.
Eptifibatide, is an antiplatelet drug of the glycoprotein IIb/IIIa inhibitor class. Eptifibatide is a cyclic heptapeptide derived from a disintegrin protein found in the venom of the southeastern pygmy rattlesnake. It belongs to the class of the arginin-glycin-aspartat-mimetics and reversibly binds to platelets. Eptifibatide has a short half-life. The drug is the third inhibitor of GPIIb/IIIa that has found broad acceptance after the specific antibody abciximab and the non-peptide tirofiban entered the global market.
P2Y12 is a chemoreceptor for adenosine diphosphate (ADP) that belongs to the Gi class of a group of G protein-coupled (GPCR) purinergic receptors. This P2Y receptor family has several receptor subtypes with different pharmacological selectivity, which overlaps in some cases, for various adenosine and uridine nucleotides. The P2Y12 receptor is involved in platelet aggregation and is thus a biological target for the treatment of thromboembolisms and other clotting disorders. Two transcript variants encoding the same isoform have been identified for this gene.
Bivalirudin, sold under the brand names Angiomax and Angiox, among others, is a specific and reversible direct thrombin inhibitor (DTI). Chemically, it is a synthetic congener of the naturally occurring drug hirudin, found in the saliva of the medicinal leech Hirudo medicinalis. It is manufactured by The Medicines Company.
A coronary stent is a tube-shaped device placed in the coronary arteries that supply blood to the heart, to keep the arteries open in patients suffering from coronary heart disease. The vast majority of stents used in modern interventional cardiology are drug-eluting stents (DES). They are used in a medical procedure called percutaneous coronary intervention (PCI). Coronary stents are divided into two broad types: drug-eluting and bare metal stents. As of 2023, drug-eluting stents were used in more than 90% of all PCI procedures. Stents reduce angina and have been shown to improve survival and decrease adverse events after a patient has suffered a heart attack—medically termed an acute myocardial infarction.
Vorapaxar is a thrombin receptor antagonist based on the natural product himbacine, discovered by Schering-Plough and developed by Merck & Co.
Ticagrelor, sold under the brand name Brilinta among others, is a medication used for the prevention of stroke, heart attack and other events in people with acute coronary syndrome, meaning problems with blood supply in the coronary arteries. It acts as a platelet aggregation inhibitor by antagonising the P2Y12 receptor. The drug is produced by AstraZeneca.
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction to the heart muscle. The most common symptom is retrosternal chest pain or discomfort that classically radiates to the left shoulder, arm, or jaw. The pain may occasionally feel like heartburn.
Cangrelor, sold under the brand name Kengreal among others, is a P2Y12 inhibitor FDA approved as of June 2015 as an antiplatelet drug for intravenous application. Some P2Y12 inhibitors are used clinically as effective inhibitors of adenosine diphosphate-mediated platelet activation and aggregation. Unlike clopidogrel (Plavix), which is a prodrug, cangrelor is an active drug not requiring metabolic conversion.
Adenosine diphosphate (ADP) receptor inhibitors are a drug class of antiplatelet agents, used in the treatment of acute coronary syndrome (ACS) or in preventive treatment for patients who are in risk of thromboembolism, myocardial infarction or a stroke. These drugs antagonize the P2Y12 platelet receptors and therefore prevent the binding of ADP to the P2Y12 receptor. This leads to a decrease in aggregation of platelets, prohibiting thrombus formation. The P2Y12 receptor is a surface bound protein found on blood platelets. They belong to G protein-coupled purinergic receptors (GPCR) and are chemoreceptors for ADP.
Management of acute coronary syndrome is targeted against the effects of reduced blood flow to the affected area of the heart muscle, usually because of a blood clot in one of the coronary arteries, the vessels that supply oxygenated blood to the myocardium. This is achieved with urgent hospitalization and medical therapy, including drugs that relieve chest pain and reduce the size of the infarct, and drugs that inhibit clot formation; for a subset of patients invasive measures are also employed. Basic principles of management are the same for all types of acute coronary syndrome. However, some important aspects of treatment depend on the presence or absence of elevation of the ST segment on the electrocardiogram, which classifies cases upon presentation to either ST segment elevation myocardial infarction (STEMI) or non-ST elevation acute coronary syndrome (NST-ACS); the latter includes unstable angina and non-ST elevation myocardial infarction (NSTEMI). Treatment is generally more aggressive for STEMI patients, and reperfusion therapy is more often reserved for them. Long-term therapy is necessary for prevention of recurrent events and complications.
Cardiovascular agents are drugs used to treat diseases associated with the heart or blood vessels. These medications are available for purchase only with a physician’s prescription. They include, but are not limited to, drugs that target hypertension (antihypertensives), hyperlipidemia (antihyperlipidemics) and blood clotting (blood-thinners) to reduce the risk of cardiovascular diseases.