Aspirin

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As the active ingredient in aspirin, acetylsalicylic acid works by inhibiting several different chemical processes within the body, including the natural physiological processes causing pain and inflammation.

Aspirin relieves pain by inhibiting production of chemicals called prostaglandins, aspirin works to diminish the body's response to a chain of chemical processes that eventually leads to pain. This mechanism of action works on a cellular level.

• Inhibits COX-1 and COX-2 activity.1016

• Pharmacologic actions similar to those of prototypical NSAIAs; exhibits anti-inflammatory, analgesic, and antipyretic activity.938

• Irreversibly acetylates and inactivates COX-1 in platelets.1016

• The existence of 2 COX isoenzymes with different aspirin sensitivities and extremely different recovery rates of their COX activity following inactivation by aspirin at least partially explains the different dosage requirements and durations of aspirin effects on platelet function versus the drug’s analgesic and anti-inflammatory effects.1016

• Effects on urinary excretion of uric acid are dose related; large dosages (e.g., 1.3 g 4 times daily) enhance urinary excretion and decrease serum concentrations of uric acid , intermediate dosages (e.g., 650 mg to 1 g 3 times daily) usually do not alter uric acid excretion, and low dosages (e.g., <325 mg 3 times daily) inhibit excretion and may increase serum uric acid concentrations.h

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Aspirin is also commercially available in combination with other drugs such as analgesics, antihistamines, antimuscarinics, antitussives, barbiturates, decongestants, and expectorants.

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Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Caplet, oral: 500 mg

Bayer Aspirin Extra Strength: 500 mg

Bayer Genuine Aspirin: 325 mg

Bayer Women's Low Dose Aspirin: 81 mg [contains elemental calcium 300 mg]

Caplet, oral [buffered]:

Ascriptin Maximum Strength: 500 mg [contains aluminum hydroxide, calcium carbonate, magnesium hydroxide]

Bayer Plus Extra Strength: 500 mg [contains calcium carbonate]

Caplet, enteric coated, oral:

Bayer Aspirin Regimen Regular Strength: 325 mg

Capsule Extended Release, oral:

Durlaza: 162.5 mg

Suppository, rectal: 300 mg (12s); 600 mg (12s)

Tablet, oral: 325 mg

Aspercin: 325 mg

Aspirtab: 325 mg

Bayer Genuine Aspirin: 325 mg

Tablet, oral [buffered]: 325 mg

Ascriptin Regular Strength: 325 mg [contains aluminum hydroxide, calcium carbonate, magnesium hydroxide]

Buffasal: 325 mg [contains magnesium oxide]

Bufferin: 325 mg [contains calcium carbonate, magnesium carbonate, magnesium oxide]

Bufferin Extra Strength: 500 mg [contains calcium carbonate, magnesium carbonate, magnesium oxide]

Buffinol: 324 mg [sugar free; contains magnesium oxide]

Tri-Buffered Aspirin: 325 mg [contains calcium carbonate, magnesium carbonate, magnesium oxide]

Tablet, chewable, oral: 81 mg

Bayer Aspirin Regimen Children's: 81 mg [cherry flavor]

Bayer Aspirin Regimen Children's: 81 mg [orange flavor]

St Joseph Adult Aspirin: 81 mg

Tablet, enteric coated, oral: 81 mg, 325 mg, 650 mg

Aspir-low: 81 mg

Bayer Aspirin Regimen Adult Low Strength: 81 mg

Ecotrin: 325 mg

Ecotrin Arthritis Strength: 500 mg

Ecotrin Low Strength: 81 mg

Halfprin: 81 mg [DSC]

St Joseph Adult Aspirin: 81 mg

Acute coronary syndromes (ST-elevation MI, non-ST-elevation MI, unstable angina)

Based on the 2013 American College of Cardiology/American Heart Association (ACCF/AHA) guidelines for the management of ST-elevation myocardial infarction (STEMI) and the 2014 ACCF/AHA guidelines for the management of non-ST-elevation acute coronary syndromes, the use of aspirin for the immediate treatment of patients presenting with symptoms suggestive of STEMI or unstable angina/non-ST-elevation myocardial infarction (UA/NSTEMI) is recommended. Patients should be instructed to chew nonenteric-coated aspirin while emergency medical services personnel are en route.

Acute ischemic stroke/transient ischemic attack

Based on the American College of Chest Physicians (ACCP) guidelines for antithrombotic therapy and prevention of thrombosis (9th edition) and the American Heart Association/American Stroke Association Guidelines for the Early Management of Patients with Acute Ischemic Stroke, the use of aspirin within 24 to 48 hours after acute ischemic stroke or transient ischemic attack onset is recommended for the treatment of most patients.

Atrial fibrillation (prevention of thromboembolism)

Primary prevention:

Two large, randomized controlled trials evaluated the use of dual antiplatelet therapy (ie, aspirin and clopidogrel) in patients with atrial fibrillation. While the use of warfarin was found to be clearly superior to the use of dual antiplatelet therapy in the ACTIVE W trial, data from the ACTIVE A trial supports the use of aspirin (in combination with clopidogrel) for the prevention of major vascular events, especially stroke, in patients with atrial fibrillation with at least 1 risk factor for stroke who in the uncommon scenario cannot take oral anticoagulants for reasons other than elevated risk of bleeding [ACTIVE Investigators 2006], [ACTIVE Investigators 2009]. In a subsequent analysis of the ACTIVE trials, the addition of clopidogrel to aspirin in patients with AF for whom warfarin was unsuitable resulted in only modest net benefit. The patient with an elevated bleeding risk who is not a candidate for oral anticoagulation would not be a candidate for dual antiplatelet therapy given the comparable risk of bleeding events [Connolly 2011].

Based on the American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guidelines for the management of atrial fibrillation, aspirin may be considered for use in patients with a CHA2DS2-VASc score of 1 as an alternative to other oral anticoagulants (eg, warfarin) to prevent thromboembolism associated with nonvalvular atrial fibrillation.

Secondary prevention:

Based on the American Heart Association/American Stroke Association (AHA/ASA) guidelines for the prevention of stroke in patients with stroke and transient ischemic attack, aspirin is recommended for use in patients with paroxysmal or permanent atrial fibrillation who have suffered ischemic stroke or transient ischemic attack and are unable to take oral anticoagulants.

Carotid artery stenosis (asymptomatic)

Based on the American College of Chest Physicians (ACCP) guidelines for antithrombotic therapy and prevention of thrombosis (9th edition), daily aspirin is suggested over no aspirin therapy in patients with asymptomatic carotid artery stenosis based on a slight reduction in total mortality observed when aspirin is taken over 10 years (regardless of cardiovascular risk profile). The American Heart Association/American Stroke Association (AHA/ASA) guidelines for the primary prevention of stroke recommend daily aspirin (in combination with a statin) for patients with asymptomatic carotid stenosis to reduce the risk of a first stroke occurring.

Colorectal cancer risk reduction (primary/secondary prevention)

Data from a large randomized double-blind trial supports the use of aspirin for the prevention of colorectal adenomas in patients previously diagnosed with colorectal cancer [Sandler 2003]. Two meta-analyses also support the use of aspirin for the primary prevention of colorectal cancer [Rothwell 2010], [Ye 2013].

Colorectal cancer risk reduction in hereditary nonpolyposis colon cancer carriers (Lynch syndrome)

Data from a large randomized phase 3 trial (CAPP2) supports the use of high-dose aspirin (600 mg daily) for the prevention of colorectal cancer in patients who are carriers of hereditary nonpolyposis colon cancer [Burn 2011].

The American Society of Clinical Oncology Guideline (Endorsement) for Hereditary Colorectal Cancer Syndromes states that although current data is based on a single trial, chemoprevention with aspirin may be used to reduce the incidence of colorectal cancer among carriers of Lynch Syndrome.

Kawasaki disease

Use of aspirin in the management of Kawasaki disease is recommended in the American Heart Association and American College of Chest Physicians guidelines.

Percutaneous coronary intervention

Based on the 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention (PCI), aspirin in conjunction with other antiplatelet agents (eg P2Y12 inhibitors and glycoprotein IIb/IIIa inhibitors) is effective in reducing the frequency of ischemic complications after PCI and recommended for use prior to the procedure and continued indefinitely.

Pericarditis

Data from a prospective open-label clinical trial supports the use of high-dose aspirin treatment in patients with acute low-risk pericarditis [Imazio 2004]. Clinical experience also suggests the utility of high-dose aspirin in managing patients with pericarditis [Imazio 2009]. Additional data may be necessary to further define the role of aspirin in this condition.

Pericarditis associated with MI

Data from a small prospective, randomized, single-blinded study comparing aspirin to indomethacin demonstrated that most patients achieve discomfort relief from pericarditis after STEMI with aspirin [Berman 1981].

Based on the American College of Cardiology Foundation/American Heart Association (ACCF/AHA) guidelines for the management of ST-elevation myocardial infarction, aspirin is recommended for the treatment of pericarditis after STEMI.

Peripheral arterial disease

Based on the 2016 American Heart Association/American College of Cardiology (AHA/ACC) guidelines for the management of lower extremity peripheral arterial disease (PAD), aspirin is recommended to reduce the risk of vascular events (ie, MI, stroke and vascular death) in patients with symptomatic PAD. The use of aspirin is reasonable in asymptomatic PAD patients with an ankle-to-brachial index ≤0.90 to reduce the risk of vascular events [AHA/ACC [Gerhard-Herman 2016]].

Based on the American College of Chest Physicians (ACCP) guidelines for antithrombotic therapy in PAD (9th edition), aspirin is recommended for patients with symptomatic or asymptomatic PAD to prevent cardiovascular events A[CCP [Alonso-Coello 2012]].

Polycythemia vera

Aspirin may be used in all patients with polycythemia vera without a history of major bleeding or gastric intolerance. Aspirin has been studied in more than 1,000 patients and is recommended in multiple polycythemia vera guidelines. Clinicians must consider the potential risk for bleeding and monitor for signs and symptoms of bleeding.

Preeclampsia (prevention)

Based on the American College of Chest Physicians guidelines, the American College of Obstetricians and Gynecologists, and the US Preventive Services Task Force [ACCP 2012], [ACOG 2013], [USPSTF 2014], low-dose aspirin is effective and recommended for use in patients at risk of preeclampsia.

Prevention (primary) of cardiovascular disease

Based on the American College of Chest Physicians guidelines and the American Diabetes Association (ADA) Standards of Medical Care in Diabetes, aspirin is effective and recommended for the primary prevention of cardiovascular disease. According to ACCP, aspirin is recommended in select patients (individuals ≥50 years without symptomatic cardiovascular disease). According to ADA, in patients with type 1 or 2 diabetes, aspirin should be considered for primary prevention in patients who have an increased cardiovascular risk, which includes most men and women ≥50 years old with at least one additional risk factor (eg, hypertension, dyslipidemia, albuminuria, family history of premature atherosclerotic cardiovascular disease, smoking).

Prevention (secondary) of cardiovascular disease (patients with diabetes)

Based on the American Diabetes Association (ADA) Standards of Medical Care in Diabetes, aspirin is effective and recommended for the secondary prevention of cardiovascular disease in patients with diabetes and a history of atherosclerotic disease.

Prevention (secondary) after CABG surgery

Based on a scientific statement from the American Heart Association on secondary prevention after coronary artery bypass graft surgery, the use of aspirin preoperatively and within 6 hours after CABG is effective and recommended for use in patients undergoing CABG. Aspirin should be continued indefinitely to reduce graft occlusion and adverse cardiac events.

Prosthetic heart valve (thromboprophylaxis)

Based on the 2014 American Heart Association/American College of Cardiology (AHA/ACC) guideline for the management of patients with valvular heart disease and the American Heart Association/American Stroke Association (AHA/ASA) guidelines for the primary prevention of stroke, aspirin in addition to a vitamin K antagonist (eg, warfarin) is effective and recommended in patients with a mechanical prosthetic valve (ie, aortic or mitral position) to reduce the risk of thromboembolism (eg, stroke) and mortality. The use of aspirin is also reasonable in all patients with a bioprosthetic aortic or mitral valve.

Additional Off-Label Uses

Aortic valve repair (thromboprophylaxis); Blalock-Taussig or Glenn shunt placement (primary prophylaxis); Fontan or Norwood surgery (primary prophylaxis); Peripheral artery percutaneous transluminal angioplasty; Peripheral artery bypass graft surgery; Rheumatic fever; Transcatheter atrial septal defect (ASD) or ventricular septal defect (VSD) devices (postprocedure prophylaxis); Ventricular assist device (VAD) placement

Note: For most cardiovascular uses, typical maintenance dosing of aspirin is 81 mg once daily. Manufacturer recommended dosing for some indications have been superseded by more recent guideline recommended doses and therefore manufacturer recommended dosing may not be represented; terminologies may also differ from manufacturer's prescribing information.

Acute coronary syndrome (ST- elevation myocardial infarction [STEMI], non-ST-elevation acute coronary syndromes [NSTE-ACS]): Oral:

Initial: 162 to 325 mg given on presentation (patient should chew nonenteric-coated aspirin especially if not taking before presentation) (ACC/AHA [Amsterdam 2014]; ACCF/AHA [O'Gara 2013]); for patients unable to take oral, may use a rectal suppository dose of 600 mg (Maalouf 2009).

Maintenance (secondary prevention): 81 to 325 mg once daily continued indefinitely; when aspirin is used with ticagrelor, the recommended maintenance dose of aspirin is 81 mg/day (ACC/AHA [Amsterdam 2014]; ACCF/AHA [O’Gara 2013]) According to the STEMI guidelines, 81 mg once daily is preferred (ACCF/AHA [O’Gara 2013]).

Concomitant antiplatelet therapy:

STEMI: Aspirin is recommended in combination with either clopidogrel, prasugrel, or ticagrelor given as early as possible or at time of PCI. In addition to dual antiplatelet therapy, parenteral anticoagulant therapy is indicated. Post-PCI stenting, consult clinical practice guidelines for recommended duration of maintenance antiplatelet therapy depending on type of stenting (ACCF/AHA [O'Gara 2013]).

NSTE-ACS:

If early-invasive strategy chosen: Aspirin is recommended in combination with either clopidogrel or ticagrelor. In addition to dual antiplatelet therapy, parenteral anticoagulant therapy is indicated. In select high-risk patients (ie, troponin positive), an IV GP IIb/IIIa inhibitor may be considered as part of initial antiplatelet therapy (if given before PCI, eptifibatide and tirofiban are preferred agents). In patients post-PCI with stenting (bare metal or drug-eluting stent), aspirin should be given with either clopidogrel, ticagrelor, or prasugrel for at least 12 months (ACC/AHA [Amsterdam 2014]).

If ischemia-guided strategy (ie, noninvasive strategy) chosen: Aspirin is recommended in combination with clopidogrel or ticagrelor for up to 12 months In addition to dual antiplatelet therapy, parenteral anticoagulant therapy is indicated. (ACC/AHA [Amsterdam 2014]).

Analgesic and antipyretic:

Oral: Immediate release: 325 to 650 mg as needed every 4 hours or 975 mg as needed every 6 hours or 500 to 1,000 mg as needed every 4 to 6 hours for no more than 10 days or as directed by health care provider; maximum daily dose: 4 g/day.

Rectal: 300 to 600 mg every 4 hours for no more than 10 days or as directed by health care provider

Anti-inflammatory (off-label dosing): Note: The use of non-aspirin NSAIDs has largely supplanted the use of aspirin for osteoarthritis, rheumatoid arthritis, and other inflammatory arthritides.

Immediate release: Oral: Usual maintenance dose: 2.1 to 7.3 g/day in divided doses (individualize dose); monitor serum salicylate concentrations especially when symptoms of salicylism (eg, tinnitus) appear; adjust dose accordingly (Csuka 1989).

Aortic valve repair (off-label use): Immediate release: Oral: 50 to 100 mg once daily (ACCP [Guyatt 2012])

Atrial fibrillation (to prevent thromboembolism) (off-label use): Oral:

Primary prevention:

Patients at low risk of ischemic stroke (CHA2DS2-VASc score of 1): Immediate release: Oral: 75 to 325 mg once daily may be considered. Note: Data has shown that adjusted-dose warfarin for stroke prevention is significantly better than aspirin in combination with clopidogrel, and aspirin in combination with clopidogrel is superior to aspirin monotherapy (ACTIVE Investigators 2009; AHA/ACC/HRS [January 2014]).

Patients unsuitable for or who choose not to take an oral anticoagulant (reasons other than bleeding concerns): Immediate release: 75 to 100 mg once daily in combination with clopidogrel. Note: Oral anticoagulation (eg, warfarin) is preferred (ACTIVE Investigators 2009); aspirin in combination with clopidogrel may be used in patients who are at low bleeding risk (ACCP [You 2012]). The patient with an elevated bleeding risk who is not a candidate for oral anticoagulation would not be a candidate for dual antiplatelet therapy given the comparable risk of bleeding events (Connolly 2011).

Secondary prevention following stroke or TIA in patients who are unable to take oral anticoagulants: Immediate release: 75 to 100 mg once daily. Monotherapy with aspirin is recommended; addition of clopidogrel to aspirin might be reasonable (AHA/ASA [Kernan 2014]).

Carotid artery stenosis (asymptomatic) (off-label use): Immediate release: Oral: 75 to 100 mg once daily (ACCP [Alonso-Coello 2012]). Note: The addition of statin therapy has also been recommended for asymptomatic carotid stenosis (AHA/ASA [Meschia 2014]). When symptomatic, the use of clopidogrel or aspirin/extended-release dipyridamole has been suggested over aspirin alone (ACCP [Alonso-Coello 2012]).

Carotid endarterectomy (off-label dosing): Immediate release: Oral: 75 to 100 mg once daily (ACCP [Alonso-Coello 2012]; AHA [Biller 1998]). The use of clopidogrel or aspirin/extended-release dipyridamole has been suggested over aspirin alone (ACCP [Alonso-Coello 2012]).

Colorectal cancer risk reduction (off-label use): Note: The optimal dose and duration of therapy for colorectal cancer risk reduction are unknown. Consider risk versus benefit ratio when initiating aspirin for this indication.

Primary/Secondary prevention: Immediate release: Oral: 75 to 325 mg once daily (Rothwell 2010; Sandler 2003; Ye 2013)

Hereditary nonpolyposis colon cancer (HNPCC; Lynch Syndrome) carriers: Immediate release: Oral: 600 mg once daily for at least 2 years (ASCO [Stoffel 2014]; Burn 2011)

Coronary artery disease (CAD), established or chronic:

Immediate release (off-label dosing): Oral: 75 to 100 mg once daily (ACCP [Guyatt 2012])

Extended release capsule: Oral: 162.5 mg once daily

Percutaneous coronary intervention (PCI) (off-label dosing): Immediate release: Oral:

Non-emergent PCI: Preprocedure: 81 to 325 mg (325 mg [nonenteric coated] in aspirin-naive patients) starting at least 2 hours (preferably 24 hours) before procedure. Postprocedure: 81 mg once daily continued indefinitely (in combination with a P2Y12 inhibitor [eg, clopidogrel, prasugrel, ticagrelor] up to 12 months) (ACCF/AHA/SCAI [Levine 2011])

Primary PCI: Preprocedure: 162 to 325 mg as early as possible prior to procedure; 325 mg preferred. Postprocedure: 81 mg once daily continued indefinitely (in combination with a P2Y12 inhibitor [eg, clopidogrel] for at least 14 days and up to 12 months) (ACCF/AHA [O'Gara 2013]).

Alternatively, in patients who have undergone elective PCI with either bare metal or drug-eluting stent placement: The American College of Chest Physicians recommends the use of 75 to 325 mg once daily (in combination with clopidogrel) for 1 month in patients receiving a bare metal stent or 3 to 6 months (dependent upon drug eluting stent type) followed by 75 to 100 mg once daily (in combination with clopidogrel) for up to 12 months. For patients who underwent PCI but did not have stent placement, 75 to 325 mg once daily (in combination with clopidogrel) for 1 month is recommended. In either case, single antiplatelet therapy (either aspirin or clopidogrel) is recommended indefinitely (ACCP [Guyatt 2012]).

Pericarditis (off-label use): Immediate release: Oral: Initial: 2.4 to 3.6 g daily in 3 to 4 divided doses; usual maintenance: 3.6 to 5.4 g daily in divided doses; gradually taper over 2- to 3-week period as appropriate (Imazio 2004; Imazio 2009).

Pericarditis in association with myocardial infarction (off-label use): Immediate release: Oral: Initial: 650 mg 4 times daily; may increase after 24 hours to 975 mg 4 times daily if necessary (ACCF/AHA [O'Gara 2013]; Berman 1981).

Peripheral arterial disease (off-label use): Immediate release: Oral: 75 to 100 mg once daily (ACCP [Guyatt 2012]) or 75 to 325 mg once daily (AHA/ACC [Gerhard-Herman 2016]). The use in combination with clopidogrel may be considered in patients with symptomatic PAD after lower extremity revascularization (AHA/ACC [Gerhard-Herman 2016]). Note: These recommendations also pertain to patients with intermittent claudication or critical limb ischemia, prior lower extremity revascularization, or prior amputation for lower extremity ischemia (Rooke 2011).

Peripheral artery percutaneous transluminal angioplasty (with or without stenting) or peripheral artery bypass graft surgery, postprocedure (off-label use): Immediate release: Oral: 75 to 100 mg once daily (ACCP [Guyatt 2012]). Note: For below-knee bypass graft surgery with prosthetic grafts, combine with clopidogrel (ACCP [Guyatt 2012]).

Polycythemia vera (off-label use): Immediate release: Oral: 75 or 100 mg once daily (Barbui 2006; McMullin 2005).

Pregnant women: 75 mg once daily (Barbui 2011; McMullin 2005).

Preeclampsia prevention (women at risk) (off-label use): Immediate release: Oral: One low-dose aspirin daily. The definition of low-dose varies by guideline and study; recommended ranges are 75 mg (ACCP [Guyatt 2012]) to 150 mg once daily (Roberge 2017; Rolnik 2017). A dose of 100 to 150 mg once daily may be more effective than lower doses (Roberge 2017). Treatment is generally started ~12 weeks gestation; however, therapy initiated after 16 weeks gestation but prior to the development of symptoms is effective (Meher 2017; Roberge 2016; Roberge 2017). Most studies discontinue therapy at ~36 to 37 weeks gestation (Roberge 2016).

Prevention (primary) of cardiovascular disease (off-label use): Immediate release: Oral:

American College of Chest Physicians: Select individuals ≥50 years (without symptomatic cardiovascular disease): 75 to 100 mg once daily (ACCP [Vandvik 2012])

American Diabetes Association: Individuals ≥50 years with diabetes type 1 or 2 who are increased cardiovascular risk: 75 to 162 mg once daily (ADA 2017)

Prevention (secondary) of cardiovascular disease (patients with diabetes) (off-label use): Immediate release: Oral: 75 to 162 mg once daily (ADA 2017)

Prevention (secondary) after coronary artery bypass graft (CABG) surgery (off-label dosing): Immediate release: Oral: 81 to 325 mg once daily administered preoperatively and within 6 hours postoperatively; continue indefinitely. Following off-pump CABG, administer aspirin 81 to 162 mg in combination with clopidogrel for 12 months (AHA [Kulik 2015]).

Prosthetic heart valve (thromboprophylaxis) (off-label use): Immediate release: Oral:

Bioprosthetic aortic valve (patient in normal sinus rhythm): 50 to 100 mg once daily (ACCP [Guyatt 2012]).

Bioprosthetic aortic or mitral valve: History of ischemic stroke or TIA before valve insertion and who are at a low risk of bleeding and no other indication for anticoagulation therapy beyond 3 to 6 months from the valve placement: 75 to 100 mg once daily is recommended in preference to long-term anticoagulation (AHA/ASA [Kernan 2014]).

Bioprosthetic mitral valve: 50 to 100 mg once daily after 3 months of anticoagulation with warfarin (ACCP [Guyatt 2012]).

Mechanical aortic or mitral valve:

Low risk of bleeding: 50 to 100 mg once daily (in combination with warfarin) (ACCP [Guyatt 2012])

History of ischemic stroke or TIA before valve insertion and who are at a low risk of bleeding: 75 to 100 mg once daily (in combination with warfarin) (AHA/ASA [Kernan 2014]).

Patients with an ischemic stroke or systemic embolism despite adequate antithrombotic therapy: 325 mg once daily (in combination with warfarin) (AHA/ASA [Kernan 2014]).

Pregnant women, mechanical or bioprosthetic: 75 to 100 mg once daily during the second and third trimesters (when used for mechanical prosthetic valve, combine with warfarin) (AHA/ACC [Nishimura 2014]).

Transcatheter aortic bioprosthetic valve: 50 to 100 mg once daily (in combination with clopidogrel) (ACCP [Guyatt 2012])

Stroke/TIA: Oral:

Acute ischemic stroke/TIA:

Immediate release (off-label dosing): Initial: 160 to 325 mg within 48 hours of stroke/TIA onset, followed by 75 to 100 mg once daily (ACCP [Guyatt 2012]). The AHA/ASA recommends an initial dose of 325 mg within 24 to 48 hours after stroke; do not administer aspirin within 24 hours after administration of alteplase (Jauch 2013). The combination of aspirin and clopidogrel might be considered within 24 hours of a minor ischemic stroke or TIA and continued for 21 days (AHA/ASA [Kernan 2014]).

Extended-release capsule: Maintenance (secondary prevention): 162.5 mg once daily. Note: Not for initial dosing during acute ischemic stroke or TIA (use immediate release)

Cardioembolic, secondary prevention (oral anticoagulation unsuitable) (off-label: Immediate release: 75 to 100 mg once daily (in combination with clopidogrel) (ACCP [Guyatt 2012]; The ACTIVE Investigators [Connolly 2009])

Cryptogenic with patent foramen ovale (PFO) or atrial septal aneurysm (off-label use): Immediate release: 50 to 100 mg once daily (ACCP [Guyatt 2012])

Intracranial atherosclerosis (50% to 99% stenosis of a major intracranial artery), secondary prevention (off-label): 325 mg once daily (consider the addition of clopidogrel for 90 days in patients with recent stroke/TIA due to severe stenosis [70% to 99%]) (AHA/ASA [Kernan 2014]).

Noncardioembolic, secondary prevention (off-label use): Immediate release: 75 to 325 mg once daily (Smith, 2011) or 75 to 100 mg once daily (ACCP [Guyatt 2012]). Note: Combination aspirin/extended release dipyridamole or clopidogrel is preferred over aspirin alone (ACCP [Guyatt 2012]).

Women at high risk for first stroke, primary prevention: Immediate release: 81 mg once daily or 100 mg every other day (AHA/ASA [Meschia 2014]).

Avoid use in severe liver disease.

Applies to aspirin: oral capsule, oral capsule delayed release, oral capsule extended release 24 hr, oral gum, oral tablet, oral tablet chewable, oral tablet effervescent, oral tablet enteric coated, oral tablet extended release

Along with its needed effects, aspirin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking aspirin:

• Abdominal or stomach pain, cramping, or burning
• black, tarry stools
• bloody or cloudy urine
• change in consciousness
• chest pain or discomfort
• confusion
• constipation
• convulsions, severe or continuing
• dark urine
• decreased frequency or amount of urine
• diarrhea
• difficult breathing
• drowsiness
• fainting
• fast breathing
• feeling that something terrible will happen
• fever
• general tiredness and weakness
• greatly decreased frequency of urination or amount of urine
• headache
• heartburn
• increased thirst
• indigestion
• irregular heartbeat
• light-colored stools
• loss of appetite
• loss of consciousness
• lower back or side pain
• muscle cramping and weakness
• muscle tremors
• nausea or vomiting
• nervousness
• numbness or tingling in the hands, feet, or lips
• panic
• rapid, deep breathing
• restlessness
• seizures
• skin rash
• stomach cramps
• swelling of the face, fingers, or lower legs
• unusual bleeding or bruising
• unusual tiredness or weakness
• upper right abdominal or stomach
• vomiting of blood or material that looks like coffee grounds
• weakness or heaviness of the legs
• weight gain
• yellow eyes and skin

Some side effects of aspirin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Acid or sour stomach
• anxiety
• belching
• dizziness
• dry mouth
• hyperventilation
• irritability
• shaking
• stomach discomfort, upset, or pain
• trouble sleeping
• unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness

• Used for the short-term relief of symptoms such as a headache, pain, and fever that occur as a result of colds, muscle trauma, menstruation, and toothache.
• May be used to relieve signs and symptoms of Rheumatoid arthritis and other types of arthritis; systemic lupus erythematosus, and spondyloarthropathies.
• Used in small doses following various heart-related revascularization procedures (such as coronary artery bypass graft [CABG]) to improve the flow of blood through the revascularized area.
• Used to reduce the risk of death or another stroke in people with a history of stroke due to blood clots or previous stroke-like events.
• Used to help prevent another heart attack or reduce the risk of death in people at risk of a heart attack, or who already have angina.
• Used off-label for several other conditions such as preeclampsia, the emergency treatment of stroke or a heart attack, and to prevent blood clots in people with atrial fibrillation (who are unable to take anticoagulants). Off-label means it is not FDA approved for this use, but there may be data to show it is safe and effective.
• Research has also shown that aspirin may help prevent colorectal cancer and the development of colorectal adenomas in people previously diagnosed with colorectal cancer. Aspirin may also reduce the incidence of colorectal cancer among people testing positive for hereditary nonpolyposis colon cancer and in carriers of Lynch syndrome.
• Generic aspirin is available.

• Takes from 5 to 30 minutes (depending on formulation) for aspirin to have an effect on platelet function. Chewed, non-coated formulations work faster.
• Needs to be taken daily to inhibit new platelets that are constantly being released into the circulation; however, platelet inhibition lasts the platelet lifetime (~10 days) due to permanent inhibition of platelet COX-1 enzyme.

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