Aspirin

Oral
Prevention of thrombotic complications following coronary artery bypass graft surgery, Secondary prevention of cardiovascular disease, Secondary prevention of thrombotic cerebrovascular disease

Oral
Fever, Mild to moderate pain

Oral
Myocardial infarction, Transient ischaemic attack, Unstable angina

Rectal
Fever, Mild to moderate pain

Severe: Contraindicated.

Severe: Contraindicated.

Should be taken with food.

Hypersensitivity to aspirin, salicylates and other NSAIDs; history of asthma attacks, angioedema, urticaria, or rhinitis precipitated by aspirin or other NSAIDs. Nasal polyps associated with asthma; active or history of recurrent peptic ulceration and gastrointestinal haemorrhage; haemorrhagic diathesis, coagulation disorders (e.g. haemophilia, thrombocytopenia), severe cardiac failure, gout. Severe renal and hepatic impairment. Children <16 years and/or those who have or are recovering from chickenpox or flu-like symptoms. Pregnancy (doses >100 mg daily during 3rd trimester) and lactation (during long-term use and/or high doses). Concomitant use with methotrexate ≥15 mg weekly.

Patient with allergic disease, asthma, chronic respiratory disease, anaemia, less severe cardiac failure, SLE, connective tissue disorders, thyrotoxicosis, hypertension, G6PD deficiency, risk factors for peptic ulcer disease (e.g. alcoholism, smoking). Patients undergoing surgical procedures, including tooth extraction. Not recommended for use during menorrhagia. Avoid use for 6 weeks following varicella vaccination. May mask signs and symptoms of infection. Concomitant use with anticoagulants (e.g. warfarin), thrombolytic, other antiplatelet agents, SSRIs, and oral corticosteroids. Avoid concomitant use with other NSAIDs. Dehydrated and debilitated patients. Mild to moderate renal and hepatic impairment. Elderly. Pregnancy (1st-2nd trimester).

Significant: Bronchospasm, asthma attacks, hypersensitivity reactions, prolonged bleeding time; reduced uric acid excretion (low dose use); haemolytic anaemia (in patients with G6PD deficiency), medication overuse headache (long-term use), salicylism (repeated use of large doses).
Blood and lymphatic system disorders: Rarely, thrombocytopenia, agranulocytosis, aplastic anaemia.
Ear and labyrinth disorders: Reduced hearing ability, tinnitus, vertigo.
Gastrointestinal disorders: Dyspepsia, nausea, vomiting, diarrhoea, mild stomach pain, heartburn.
Hepatobiliary disorders: Hepatic insufficiency, hepatitis.
Investigations: Increased transaminases.
Nervous system disorders: Headache.
Renal and urinary disorders: Impaired renal function, Na and fluid retention, urate kidney stones, haematuria.
Reproductive system and breast disorders: Rarely, menorrhagia.
Respiratory, thoracic and mediastinal disorders: Rhinitis, dyspnoea.
Skin and subcutaneous tissue disorders: Urticaria.
Potentially Fatal: Gastrointestinal bleeding, ulceration, and perforation. Rarely, Reye's syndrome, serious skin reactions (e.g. Stevens-Johnson syndrome, erythema multiforme, toxic epidermal necrolysis).

Obtain CBC, Fe studies, ferritin, stools for occult blood, and liver and renal function tests during prolonged therapy. Monitor for signs and symptoms of hypersensitivity reactions and bleeding.

Symptoms: Vomiting, nausea, abdominal pain, dehydration, tinnitus, headache, vertigo, deafness, hearing disorders, sweating, warm extremities with bounding pulses, hyperventilation resulting in respiratory alkalosis, metabolic acidosis with normal or high arterial pH (normal or reduced hydrogen ion concentration), haematemesis, hyperpyrexia, hypoglycaemia, hypokalaemia, thrombocytopenia, increased INR, intravascular coagulation, renal failure, non-cardiac pulmonary oedema, hyperthermia, restlessness, hallucinations, confusion, disorientation, convulsions, CV collapse, respiratory arrest, coma. Management: Symptomatic and supportive treatment. Induce vomiting in the event of moderate intoxication; if unsuccessful, consider performing gastric lavage in adults and children who ingested >500 mg/kg salicylate within 1 hour of presentation, then administer activated charcoal for ingestion of >250 mg/kg salicylate. Perform urinary alkalinisation by administration of 1.26% Na bicarbonate and monitor urine pH levels. Maintain fluid and electrolyte balance. Correct metabolic acidosis with 8.4% Na bicarbonate IV. For severe poisoning and plasma concentrations >700 mg/L or lower concentrations associated with severe clinical or metabolic features, haemodialysis is the treatment of choice.

Increased risk of bleeding with other antiplatelet agents (e.g. clopidogrel, dipyridamole), anticoagulants (e.g. heparin, warfarin), and thrombolytics. Increased risk of gastrointestinal bleeding or ulceration with other NSAIDs, SSRIs (e.g. sertraline, paroxetine), and corticosteroids. Reverses the effect of uricosuric agents (e.g. probenecid, sulfinpyrazone). May increase the effects of antidiabetics (e.g. sulfonylureas, insulins) and thiopental. Impairs the renal excretion of lithium and digoxin, thus increasing the plasma concentrations of the drugs. Increased excretion with antacids. May decrease the effects of diuretics (e.g. spironolactone, furosemide) and antihypertensive agents (e.g. ACE inhibitors, β-blockers). May result in severe acidosis and increased CNS toxicity with carbonic anhydrase inhibitors (e.g. acetazolamide). May increase the nephrotoxic effect of ciclosporin and tacrolimus. Increases the plasma concentration of zafirlukast. Reduces the binding of phenytoin and valproic acid to serum albumin, resulting in increased free concentration of the drugs. Concomitant use with metamizole or ibuprofen may reduce the cardioprotective effect of aspirin. May enhance the adverse or toxic effect of varicella virus-containing vaccines (particularly the risk for Reye's syndrome), sulfonamides, and vancomycin (particularly ototoxicity). Increased rate of absorption with metoclopramide and domperidone.
Potentially Fatal: Enhances the haematological toxicity of methotrexate, particularly when used at doses ≥15 mg weekly.

Increased risk of gastrointestinal bleeding with alcohol. Decreased rate but not the extent of absorption with food.

May lead to false-negative results for glucose oxidase urinary glucose tests. May lead to false-positive results of aldosterone/renin ratio (ARR) and when using cupric sulfate method. Aspirin interferes with Gerhardt test, vanillylmandelic acid (VMA) determination, 5-hydroxyindoleacetic acid, xylose tolerance test, and thyroid function tests (T₃ and T₄).

Description: Aspirin is a salicylate that exhibits analgesic, anti-inflammatory, and antipyretic activities. It is an irreversible inhibitor of cyclooxygenase-1 and 2 (COX-1 and 2) enzymes, resulting in direct inhibition of the biosynthesis of prostaglandins. It inhibits platelet aggregation via acetylation of platelet cyclooxygenase, thus irreversibly preventing the formation of platelet aggregating factor thromboxane A₂.
Synonym: acetylsalicylic acid (ASA).
Onset: Platelet inhibition: <1 hour (nonenteric-coated tab); 3-4 hours (enteric-coated tab); 20 minutes (when chewing nonenteric- or enteric-coated tab).
Duration: Oral: 4-6 hours. Platelet inhibition: Approx 10 days.
Pharmacokinetics:
Absorption: Rapidly and well absorbed from the gastrointestinal tract (oral). Food reduces the rate but not the extent of absorption. Bioavailability: 50-75%. Time to peak plasma concentration: Nonenteric-coated tab: Approx 1-2 hours (20 minutes when chewed); Enteric-coated tab: 3-4 hours (2 hours when chewed).
Distribution: Widely and readily distributed into most body tissues and fluids. Crosses the placenta and enters breast milk. Volume of distribution: 10 L. Plasma protein binding: Aspirin: 33%. Salicylate: 90-95% (<100 mcg/mL concentration); 70-85% (100-400 mcg/mL concentration); 25-60% (>400 mcg/mL concentration).
Metabolism: Partially hydrolysed by esterases in the gastrointestinal mucosa to salicylate (active), which is then conjugated in the liver into salicyluric acid, salicyl phenolic glucuronide, salicylic acyl glucuronide, gentisic acid, and gentisuric acid.
Excretion: Via urine (75% as salicyluric acid, 10% as salicylic acid, 10% as phenolic glucuronide, 5% as acyl glucuronide). Elimination half-life: Aspirin: 15-20 minutes (plasma concentration). Salicylate: Approx 2-3 hours (325 mg dose); 15-30 hours (high doses).

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 2244, Aspirin. https://pubchem.ncbi.nlm.nih.gov/compound/Aspirin. Accessed Sept. 27, 2022.

Tab/cap/caplets: Store below 30°C. Rectal supp: Store between 2-15°C. Do not freeze. Storage recommendations may vary among countries or individual products. Refer to specific product guidelines.

Anticoagulants, Antiplatelets & Fibrinolytics (Thrombolytics) / Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)

N02BA01 - acetylsalicylic acid ; Belongs to the class of salicylic acids and derivatives agents. Used to relieve pain and fever.
B01AC06 - acetylsalicylic acid ; Belongs to the class of platelet aggregation inhibitors excluding heparin. Used in the treatment of thrombosis.

Adult Aspirin Regimen Low Dose Tablet, Delayed Release (Cardinal Health 110, LLC. DBA Leader). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 19/08/2022.

Anon. Aspirin. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 01/04/2022.

Anon. Aspirin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/04/2022.

Aspirin 300 mg Caplets (Euro-Link Pharma Ltd). MHRA. https://products.mhra.gov.uk. Accessed 01/04/2022.

Aspirin 300 mg Dispersible Tablets (Accord-UK Ltd). MHRA. https://products.mhra.gov.uk. Accessed 01/04/2022.

Aspirin 300 mg Tablets BP (Bristol Laboratories Ltd). MHRA. https://products.mhra.gov.uk. Accessed 01/04/2022.

Aspirin 75 mg Dispersible Tablets (Accord-UK Ltd). MHRA. https://products.mhra.gov.uk. Accessed 01/04/2022.

Aspirin 75 mg Tablets (Intrapharm Laboratories Limited). MHRA. https://products.mhra.gov.uk. Accessed 01/04/2022.

Aspirin Cardio Enteric-coated Tablets (Bayer Co. [Malaysia] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 19/08/2022.

Aspirin Enteric Coated Tablets 75 mg (Ennogen Pharma Limited). MHRA. https://products.mhra.gov.uk. Accessed 01/04/2022.

Aspirin Suppository (Padagis US LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 19/08/2022.

Asthromed 100 mg Enteric Coated Tablet (Medhaus Pharma, Inc.). MIMS Philippines. http://www.mims.com/philippines. Accessed 22/08/2022.

Bayer Aspirin Extra Strength Caplets (Bayer HealthCare LLC.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 19/08/2022.

Bayer Aspirin Regimen Enteric Coated (Bayer HealthCare LLC.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 19/08/2022.

Bayer Aspirin Tablet 500 mg (Bayer Co. [Malaysia] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 19/08/2022.

Besprin 100 mg Enteric-coated Tablet (Lloyd Laboratories, Inc.). MIMS Philippines. http://www.mims.com/philippines. Accessed 22/08/2022.

Buckingham R (ed). Aspirin. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/04/2022.

Joint Formulary Committee. Aspirin. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/04/2022.

Nu-Seals 75, Aspirin 75 mg Gastro-resistant Tablets, PostMI 75 EC, Nu-Seals Cardio 75 (Alliance Pharmaceuticals Limited). MHRA. https://products.mhra.gov.uk. Accessed 18/08/2022.

Resprin Suppositories 150 mg (Martindale Pharmaceuticals Limited). MHRA. https://products.mhra.gov.uk. Accessed 01/04/2022.

Resprin Suppositories 300 mg (Martindale Pharmaceuticals Limited). MHRA. https://products.mhra.gov.uk. Accessed 01/04/2022.

Samjin Aspirin Enteric-coated Tablet (Samjin Pharm. Co., Ltd.). MIMS Hong Kong. http://www.mims.com/hongkong. Accessed 22/08/2022.

Vazalore Capsule (PLx Pharma Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 19/08/2022.

Winspirin Dispersible Tablet 300 mg (KCK Pharmaceutical Industries Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 19/08/2022.

Winspirin Dispersible Tablet 75 mg (KCK Pharmaceutical Industries Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 22/08/2022.