Product Name
:
S-PRIN
Chemical Name
:
Acetyl Salicylic Acid
Therapeutic Category
:
Cardiovascular drugs
Pharmacologic Category
:
Antiplatelet Agent - Salicylate
Pharmaceutical Form
:
Tablets
Composition
:
Acetyl Salicylic Acid 100mg / 325mg
Dosing
 
Dosing: Adult
Analgesic and antipyretic:
Oral: 325-650 mg every 4-6 hours up to 4 g/day
Anti-inflammatory: Oral: Initial: 2.4-3.6 g/day in divided doses; usual maintenance: 3.6-5.4 g/day; monitor serum concentrations
Atrial fibrillation (in patients not candidates for warfarin or at low risk of ischemic stroke): Oral: 75-325 mg once daily (Fuster, 2006; Singer, 2008) or 75-100 mg once daily (Furie, 2011)
CABG: Oral: 75-100 mg once daily (usual dose: 81 mg) initiated 6 hours following surgery; if bleeding prevents administration at 6 hours after CABG, initiate as soon as possible (Becker, 2008)
CABG (internal mammary bypass graft): Oral: 75-162 mg once daily (Becker, 2008)
Carotid artery stenting: Oral: 81-325 mg once daily beginning at least 24 hours (preferably 4 days) prior to procedure with concomitant clopidogrel (Bates, 2007)
Carotid endarterectomy: Oral: 50-100 mg once daily preoperatively and daily thereafter; usual dose: 81 mg once daily (Albers, 2008)
Heart valve (bioprosthetic, mechanical): Oral: 50-100 mg once daily (in addition to warfarin) (Furie, 2011); usual dose: 81 mg once daily (Salem, 2008)
Mechanical heart valve (history of thromboembolism while receiving oral anticoagulants): Oral: 75-100 mg once daily (in addition to warfarin) (Furie, 2011); usual dose: 81 mg once daily
Mitral valve (prolapse, annular calcification) (with documented stroke or TIA): Oral: 50-100 mg once daily; usual dose: 81 mg once daily (Salem, 2008)
Myocardial infarction (primary prevention): Oral: 75-162 mg once daily (Antman, 2004) or 75-100 mg (usual dose: 81 mg) once daily (Hirsh, 2008)
Myocardial infarction (ST-segment elevation myocardial infarction [STEMI], non-ST-segment elevation myocardial infarction [NSTEMI]): Oral: Initial: 162-325 mg given on presentation (patient should chew nonenteric-coated aspirin especially if not taking before presentation); for patients unable to take oral, may use rectal suppository (300 mg). Maintenance (secondary prevention): 75-162 mg once daily indefinitely (Anderson, 2007; Antman, 2004).
PCI: Oral: Initial: 75-325 mg (300-325 mg in aspirin naive patients) starting at least 2 hours (preferably 24 hours) before procedure; post procedure: 162-325 mg once daily (dose and duration varies with type of stent implanted); Note: Dose may be reduced to 75-162 mg once daily after appropriate duration based on stent-type is complete (King, 2008).
Pericarditis associated with myocardial infarction: Oral: 162-325 mg once daily; doses as high as 650 mg every 4-6 hours may be required; enteric-coated recommended (Antman, 2004)
Peripheral arterial disease: Oral: 75-100 mg once daily; usual dose: 81 mg once daily (Sobel, 2008) or 75-325 mg once daily; may use in conjunction with clopidogrel in those who are not at an increased risk of bleeding but are of high cardiovascular risk (Class IIb recommendation). Note: These recommendations also pertain to those with intermittent claudication or critical limb ischemia, prior lower extremity revascularization, or prior amputation for lower extremity ischemia (Rooke, 2011).
Pre-eclampsia prevention: Oral: 60-81 mg once daily (usual dose: 81 mg) during gestational weeks 13-26 (patient selection criteria not established) (Bates, 2008; CLASP, 1994)
Stroke (acute ischemic): Oral: Initial: 150-325 mg within 48 hours of stroke onset (in patients who are not candidates for thrombolytic therapy), followed by 50-100 mg once daily (Albers, 2008)
Stroke (cardioembolic; anticoagulation contraindicated): Oral: 75-325 mg once daily (Albers, 2008)
Stroke/TIA (noncardioembolic; secondary prevention): Oral: 50-325 mg once daily (Adams, 2007) or 50-100 mg once daily; usual dose: 81 mg once daily (Hirsh, 2008). Note: Combination aspirin 25 mg and extended release dipyridamole 200 mg twice daily is preferred over aspirin alone (Albers, 2008).
Stroke (women at high risk for CVA, primary prevention): Oral: 81 mg once daily or 100 mg every other day (Goldstein, 2010)

Dosing: Pediatric

Analgesic and antipyretic: Oral, rectal: 10-15 mg/kg/dose every 4-6 hours, up to a total of 4 g/day
Anti-inflammatory: Oral: Initial: 60-90 mg/kg/day in divided doses; usual maintenance: 80-100 mg/kg/day divided every 6-8 hours; monitor serum concentrations
Antiplatelet effects: Oral: Adequate pediatric studies have not been performed; pediatric dosage is derived from adult studies and clinical experience and is not well established; suggested doses have ranged from 3-5 mg/kg/day to 5-10 mg/kg/day given as a single daily dose. Doses are rounded to a convenient amount (eg, 1/2 of 81 mg tablet).
Mechanical prosthetic heart valves: Oral: 6-20 mg/kg/day given as a single daily dose (used in combination with an oral anticoagulant in children who have systemic embolism despite adequate oral anticoagulation therapy (INR 2.5-3.5) and used in combination with low-dose anticoagulation (INR 2-3) and dipyridamole when full-dose oral anticoagulation is contraindicated)
Blalock-Taussig shunts (unlabeled use): Oral: 1-5 mg/kg/day given as a single daily dose (Monagle, 2008)
Cerebrovascular accident (non-sickle cell-related ischemic stroke) (unlabeled use): 1-5 mg/kg/day for at least 2 years (Monagle, 2008)
Kawasaki disease (unlabeled use): Oral: 80-100 mg/kg/day divided every 6 hours; monitor serum concentrations; after fever resolves: 1-5 mg/kg/day once daily; in patients without coronary artery abnormalities, give lower dose for at least 6-8 weeks or until ESR and platelet count are normal; in patients with coronary artery abnormalities, low-dose aspirin should be continued indefinitely (Monagle, 2008)

Dosing: Geriatric

Refer to adult dosing.

Dosing: Renal Impairment

Clcr <10 mL/minute: Avoid use.
Dialyzable (50% to 100%)

Dosing: Hepatic Impairment

Avoid use in severe liver disease.
Use
 
Treatment of mild-to-moderate pain, inflammation, and fever; prevention and treatment of myocardial infarction (MI), acute ischemic stroke, and transient ischemic episodes; management of rheumatoid arthritis, rheumatic fever, osteoarthritis; adjunctive therapy in revascularization procedures (coronary artery bypass graft [CABG], percutaneous transluminal coronary angioplasty [PTCA], carotid endarterectomy), stent implantation
Use - Unlabeled/Investigational
Low doses have been used in the prevention of pre-eclampsia, complications associated with autoimmune disorders such as lupus or antiphospholipid syndrome; colorectal cancer; Kawasaki disease; alternative therapy for prevention of thromboembolism associated with atrial fibrillation in patients not candidates for warfarin; pericarditis associated with MI; prosthetic valve thromboprophylaxis; peripheral arterial occlusive disease
Adverse Reactions
 
As with all drugs which may affect hemostasis, bleeding is associated with aspirin. Hemorrhage may occur at virtually any site. Risk is dependent on multiple variables including dosage, concurrent use of multiple agents which alter hemostasis, and patient susceptibility. Many adverse effects of aspirin are dose related, and are extremely rare at low dosages. Other serious reactions are idiosyncratic, related to allergy or individual sensitivity. Accurate estimation of frequencies is not possible.
Cardiovascular: Hypotension, tachycardia, dysrhythmias, edema
Central nervous system: Fatigue, insomnia, nervousness, agitation, confusion, dizziness, headache, lethargy, cerebral edema, hyperthermia, coma
Dermatologic: Rash, angioedema, urticaria
Endocrine & metabolic: Acidosis, hyperkalemia, dehydration, hypoglycemia (children), hyperglycemia, hypernatremia (buffered forms)
Gastrointestinal: Nausea, vomiting, dyspepsia, epigastric discomfort, heartburn, stomach pain, gastrointestinal ulceration (6% to 31%), gastric erosions, gastric erythema, duodenal ulcers
Hematologic: Anemia, disseminated intravascular coagulation (DIC), prothrombin times prolonged, coagulopathy, thrombocytopenia, hemolytic anemia, bleeding, iron-deficiency anemia
Hepatic: Hepatotoxicity, transaminases increased, hepatitis (reversible)
Neuromuscular & skeletal: Rhabdomyolysis, weakness, acetabular bone destruction (OA)
Otic: Hearing loss, tinnitus
Renal: Interstitial nephritis, papillary necrosis, proteinuria, renal failure (including cases caused by rhabdomyolysis), BUN increased, serum creatinine increased
Respiratory: Asthma, bronchospasm, dyspnea, laryngeal edema, hyperpnea, tachypnea, respiratory alkalosis, noncardiogenic pulmonary edema
Miscellaneous: Anaphylaxis, prolonged pregnancy and labor, stillbirths, low birth weight, peripartum bleeding, Reye's syndrome
Postmarketing and/or case reports: Colonic ulceration, esophageal stricture, esophagitis with esophageal ulcer, esophageal hematoma, oral mucosal ulcers (aspirin-containing chewing gum), coronary artery spasm, conduction defect and atrial fibrillation (toxicity), delirium, ischemic brain infarction, colitis, rectal stenosis (suppository), cholestatic jaundice, periorbital edema, rhinosinusitis
Contraindications
 
Hypersensitivity to salicylates, other NSAIDs, or any component of the formulation; asthma; rhinitis; nasal polyps; inherited or acquired bleeding disorders (including factor VII and factor IX deficiency); do not use in children (<16 years of age) for viral infections (chickenpox or flu symptoms), with or without fever, due to a potential association with Reye's syndrome; pregnancy (3rd trimester especially)
Warnings / Precautions Drug
 
Concerns related to adverse effects:
• Salicylate sensitivity: Patients with sensitivity to tartrazine dyes, nasal polyps, and asthma may have an increased risk of salicylate sensitivity.
• Tinnitus: Discontinue use if tinnitus or impaired hearing occurs.
• Upper gastrointestinal (UGI) events (eg, symptomatic or complicated ulcers): Low-dose aspirin for cardioprotective effects is associated with a two- to fourfold increase in UGI events. The risks of these events increase with increasing aspirin dose; during the chronic phase of aspirin dosing, doses >81 mg are not recommended unless indicated (Bhatt, 2008).
Disease-related concerns:
• Bleeding disorders: Use with caution in patients with platelet and bleeding disorders.
• Dehydration: Use with caution in patients with dehydration.
• Ethanol use: Heavy ethanol use (>3 drinks/day) can increase bleeding risks.
• Gastrointestinal disease: Use with caution in patients with erosive gastritis or peptic ulcer disease.
• Hepatic impairment: Avoid use in severe hepatic failure.
• Renal impairment: Use with caution in patients with mild-to-moderate renal impairment (only at high dosages); avoid in severe impairment.
Concurrent drug therapy issues:
• Alteplase: In the treatment of acute ischemic stroke, avoid aspirin for 24 hours following administration of alteplase; administration within 24 hours increases the risk of hemorrhagic transformation.
• Aspirin: Concurrent use of aspirin and clopidogrel is not recommended for secondary prevention of ischemic stroke or TIA in patients unable to take oral anticoagulants due to hemorrhagic risk (Furie, 2011).
• COX-2 inhibitors/NSAIDs: When used concomitantly with ≤325 mg of aspirin, NSAIDs (including selective COX-2 inhibitors) substantially increase the risk of gastrointestinal complications (eg, ulcer); concomitant gastroprotective therapy (eg, proton pump inhibitors) is recommended (Bhatt, 2008).
Special populations:
• Pediatrics: When used for self-medication (OTC labeling): Children and teenagers who have or are recovering from chickenpox or flu-like symptoms should not use this product. Changes in behavior (along with nausea and vomiting) may be an early sign of Reye's syndrome; patients should be instructed to contact their healthcare provider if these occur.
• Surgical patients: ASA should be avoided (if possible) in surgical patients for 1-2 weeks prior to surgery, to reduce the risk of excessive bleeding (except in patients with cardiac stents that have not completed their full course of dual antiplatelet therapy [aspirin, clopidogrel]; patient specific situations need to be discussed with cardiologist; AHA/ACC/SCAI/ACS/ADA Science Advisory provides recommendations).
Metabolism/Transport Effects
Substrate of CYP2C9 (minor)
Interactions
 
ACE Inhibitors: Salicylates may diminish the antihypertensive effect of ACE Inhibitors. They may also diminish other beneficial pharmacodynamic effects desired for the treatment of CHF. The effects are likely dose-related. 100 mg doses aspirin appear to cause no problems, whereas 300 mg doses appear to significantly affect ACE Inhibitor efficacy. Risk C: Monitor therapy
Alendronate: Aspirin may enhance the adverse/toxic effect of Alendronate. Specifically gastrointestinal adverse events. Risk C: Monitor therapy
Ammonium Chloride: May increase the serum concentration of Salicylates. Risk C: Monitor therapy
Anticoagulants: Salicylates may enhance the anticoagulant effect of Anticoagulants. Risk C: Monitor therapy
Antidepressants (Tricyclic, Tertiary Amine): May enhance the antiplatelet effect of Aspirin. Risk C: Monitor therapy
Antiplatelet Agents: May enhance the adverse/toxic effect of Salicylates. Increased risk of bleeding may result. Risk C: Monitor therapy
Calcium Channel Blockers (Nondihydropyridine): May enhance the anticoagulant effect of Salicylates. Exceptions: Bepridil [Off Market]. Risk C: Monitor therapy
Carbonic Anhydrase Inhibitors: Salicylates may enhance the adverse/toxic effect of Carbonic Anhydrase Inhibitors. Salicylate toxicity might be enhanced by this same combination. Exceptions: Brinzolamide; Dorzolamide. Risk D: Consider therapy modification
Collagenase (Systemic): Antiplatelet Agents may enhance the adverse/toxic effect of Collagenase (Systemic). Specifically, the risk of injection site bruising and/or bleeding may be increased. Risk C: Monitor therapy
Corticosteroids (Systemic): Salicylates may enhance the adverse/toxic effect of Corticosteroids (Systemic). These specifically include gastrointestinal ulceration and bleeding. Corticosteroids (Systemic) may decrease the serum concentration of Salicylates. Withdrawal of corticosteroids may result in salicylate toxicity. Risk C: Monitor therapy
Dasatinib: May enhance the anticoagulant effect of Antiplatelet Agents. Risk C: Monitor therapy
Divalproex: Salicylates may increase the serum concentration of Divalproex. Risk C: Monitor therapy
Drotrecogin Alfa: Salicylates may enhance the adverse/toxic effect of Drotrecogin Alfa. Bleeding may occur. Management: Weigh potential benefits of drotrecogin against increased bleeding risk in patients who have received platelet inhibitors including aspirin (over 650 mg daily within 1 week). Monitor for bleeding and stop infusion if clinically important bleeding occurs. Risk D: Consider therapy modification
Floctafenine: May enhance the adverse/toxic effect of Aspirin. Risk X: Avoid combination
Ginkgo Biloba: May enhance the anticoagulant effect of Salicylates. Management: Consider alternatives to this combination of agents. Monitor for signs and symptoms of bleeding (especially intracranial bleeding) if salicylates are used in combination with ginkgo biloba. Risk D: Consider therapy modification
Glucosamine: May enhance the antiplatelet effect of Antiplatelet Agents. Risk C: Monitor therapy
Heparin: Aspirin may enhance the anticoagulant effect of Heparin. Risk C: Monitor therapy
Herbs (Anticoagulant/Antiplatelet Properties) (eg, Alfalfa, Anise, Bilberry): May enhance the adverse/toxic effect of Salicylates. Bleeding may occur. Risk D: Consider therapy modification
Ibritumomab: Antiplatelet Agents may enhance the adverse/toxic effect of Ibritumomab. Both agents may contribute to impaired platelet function and an increased risk of bleeding. Risk C: Monitor therapy
Influenza Virus Vaccine (Live/Attenuated): May enhance the adverse/toxic effect of Salicylates. Specifically, Reye's syndrome may develop. Risk X: Avoid combination
Ketorolac: May enhance the adverse/toxic effect of Aspirin. Risk X: Avoid combination
Ketorolac (Nasal): May enhance the adverse/toxic effect of Aspirin. Risk X: Avoid combination
Ketorolac (Systemic): May enhance the adverse/toxic effect of Aspirin. Risk X: Avoid combination
Loop Diuretics: Salicylates may diminish the diuretic effect of Loop Diuretics. Loop Diuretics may increase the serum concentration of Salicylates. Risk C: Monitor therapy
Methotrexate: Salicylates may increase the serum concentration of Methotrexate. Salicylate doses used for prophylaxis of cardiovascular events are not likely to be of concern. Risk D: Consider therapy modification
Nonsteroidal Anti-Inflammatory Agents: May enhance the adverse/toxic effect of Antiplatelet Agents. An increased risk of bleeding may occur. Nonsteroidal Anti-Inflammatory Agents may diminish the cardioprotective effect of Antiplatelet Agents. This interaction is likely specific to aspirin, and not to other antiplatelet agents. Risk C: Monitor therapy
NSAID (Nonselective): May enhance the adverse/toxic effect of Salicylates. An increased risk of bleeding may be associated with use of this combination. NSAID (Nonselective) may diminish the cardioprotective effect of Salicylates. Salicylates may decrease the serum concentration of NSAID (Nonselective). Exceptions: Diclofenac. Risk D: Consider therapy modification
Omega-3-Acid Ethyl Esters: May enhance the antiplatelet effect of Antiplatelet Agents. Risk C: Monitor therapy
Pentosan Polysulfate Sodium: May enhance the adverse/toxic effect of Antiplatelet Agents. Specifically, the risk of bleeding may be increased by concurrent use of these agents. Risk C: Monitor therapy
Pentoxifylline: May enhance the antiplatelet effect of Antiplatelet Agents. Risk C: Monitor therapy
Potassium Acid Phosphate: May increase the serum concentration of Salicylates. Risk C: Monitor therapy
PRALAtrexate: Salicylates may increase the serum concentration of PRALAtrexate. Salicylate doses used for prophylaxis of cardiovascular events are unlikely to be of concern. Risk D: Consider therapy modification
Probenecid: Salicylates may diminish the therapeutic effect of Probenecid. Risk C: Monitor therapy
Prostacyclin Analogues: May enhance the antiplatelet effect of Antiplatelet Agents. Risk C: Monitor therapy
Rivaroxaban: Antiplatelet Agents may enhance the anticoagulant effect of Rivaroxaban. Management: Avoid concurrent use of clopidogrel with rivaroxaban unless the anticipated benefits outweigh the risks of bleeding. Avoid concurrent use of rivaroxaban with other antiplatelet agents whenever possible. Risk D: Consider therapy modification
Salicylates: May enhance the anticoagulant effect of other Salicylates. Risk C: Monitor therapy
Selective Serotonin Reuptake Inhibitors: May enhance the antiplatelet effect of Aspirin. Risk C: Monitor therapy
Serotonin/Norepinephrine Reuptake Inhibitors: May enhance the antiplatelet effect of Aspirin. Risk C: Monitor therapy
Sulfonylureas: Salicylates may enhance the hypoglycemic effect of Sulfonylureas. Of concern with regular, higher doses of salicylates, not sporadic, low doses. Risk C: Monitor therapy
Thrombolytic Agents: Salicylates may enhance the adverse/toxic effect of Thrombolytic Agents. An increased risk of bleeding may occur. Risk C: Monitor therapy
Ticagrelor: Aspirin may enhance the antiplatelet effect of Ticagrelor. Aspirin may diminish the therapeutic effect of Ticagrelor. More specifically, the benefits of ticagrelor relative to clopidogrel may be diminished in patients receiving daily aspirin doses greater than 100-150 mg daily. Management: Avoid daily aspirin doses greater than 100 mg in patients receiving ticagrelor. Canadian recommendations are to avoid daily aspirin doses greater than 150 mg. Daily low-dose aspirin (U.S.: 75-100 mg; Canada: 75-150 mg) is recommended. Risk D: Consider therapy modification
Tiludronate: Aspirin may decrease the serum concentration of Tiludronate. Risk C: Monitor therapy
Tositumomab and Iodine I 131 Tositumomab: Antiplatelet Agents may enhance the adverse/toxic effect of Tositumomab and Iodine I 131 Tositumomab. Specifically, the risk of bleeding-related adverse events may be increased. Risk C: Monitor therapy
Treprostinil: May enhance the adverse/toxic effect of Salicylates. Bleeding may occur. Risk C: Monitor therapy
Valproic Acid: Salicylates may increase the serum concentration of Valproic Acid. Risk C: Monitor therapy
Varicella Virus-Containing Vaccines: Salicylates may enhance the adverse/toxic effect of Varicella Virus-Containing Vaccines. Reye's Syndrome may develop. Risk D: Consider therapy modification
Vitamin E: May enhance the antiplatelet effect of Antiplatelet Agents. Risk C: Monitor therapy
Vitamin K Antagonists (eg, warfarin): Salicylates may enhance the anticoagulant effect of Vitamin K Antagonists. Risk D: Consider therapy modification
Ethanol/Nutrition/Herb Interactions
Ethanol: Avoid ethanol (may enhance gastric mucosal damage).
Food: Food may decrease the rate but not the extent of oral absorption.
Folic acid: Hyperexcretion of folate; folic acid deficiency may result, leading to macrocytic anemia.
Iron: With chronic aspirin use and at doses of 3-4 g/day, iron-deficiency anemia may result.
Sodium: Hypernatremia resulting from buffered aspirin solutions or sodium salicylate containing high sodium content. Avoid or use with caution in CHF or any condition where hypernatremia would be detrimental.
Benedictine liqueur, prunes, raisins, tea, and gherkins: Potential salicylate accumulation.
Fresh fruits containing vitamin C: Displace drug from binding sites, resulting in increased urinary excretion of aspirin.
Herb/Nutraceutical: Avoid cat's claw, dong quai, evening primrose, feverfew, garlic, ginger, ginkgo, red clover, horse chestnut, green tea, ginseng (all have additional antiplatelet activity). Limit curry powder, paprika, licorice; may cause salicylate accumulation. These foods contain 6 mg salicylate/100 g. An ordinary American diet contains 10-200 mg/day of salicylate.
Pregnancy
 
Salicylates have been noted to cross the placenta and enter fetal circulation. Adverse effects reported in the fetus include mortality, intrauterine growth retardation, salicylate intoxication, bleeding abnormalities, and neonatal acidosis. Use of aspirin close to delivery may cause premature closure of the ductus arteriosus. Adverse effects reported in the mother include anemia, hemorrhage, prolonged gestation, and prolonged labor. Aspirin has been used for the prevention of pre-eclampsia; however, the ACOG currently recommends that it not be used in low-risk women. Low-dose aspirin is used to treat complications resulting from antiphospholipid syndrome in pregnancy (either primary or secondary to SLE). In general, low doses during pregnancy needed for the treatment of certain medical conditions have not been shown to cause fetal harm, however, discontinuing therapy prior to delivery is recommended. Use of safer agents for routine management of pain or headache should be considered.
Lactation
 
Enters breast milk (AAP recommends use “with caution”; AAP 2001 update pending)
Breast-Feeding Considerations
Low amounts of aspirin can be found in breast milk. Milk/plasma ratios ranging from 0.03-0.3 have been reported. Peak levels in breast milk are reported to be at ~9 hours after a dose. Metabolic acidosis was reported in one infant following an aspirin dose of 3.9 g/day in the mother. The WHO considers occasional doses of aspirin to be compatible with breast-feeding, but to avoid long-term therapy and consider monitoring the infant for adverse effects. Other sources suggest avoiding aspirin while breast-feeding due to the theoretical risk of Reye's syndrome.
Mechanism of Action
 
Irreversibly inhibits cyclooxygenase-1 and 2 (COX-1 and 2) enzymes, via acetylation, which results in decreased formation of prostaglandin precursors; irreversibly inhibits formation of prostaglandin derivative, thromboxane A2, via acetylation of platelet cyclooxygenase, thus inhibiting platelet aggregation; has antipyretic, analgesic, and anti-inflammatory properties
Pharmacodynamics / Kinetics
 
Duration: 4-6 hours
Absorption: Rapid
Distribution: Vd: 10 L; readily into most body fluids and tissues
Metabolism: Hydrolyzed to salicylate (active) by esterases in GI mucosa, red blood cells, synovial fluid, and blood; metabolism of salicylate occurs primarily by hepatic conjugation; metabolic pathways are saturable
Bioavailability: 50% to 75% reaches systemic circulation
Half-life elimination: Parent drug: 15-20 minutes; Salicylates (dose dependent): 3 hours at lower doses (300-600 mg), 5-6 hours (after 1 g), 10 hours with higher doses
Time to peak, serum: ~1-2 hours
Excretion: Urine (75% as salicyluric acid, 10% as salicylic acid)