Aspirin (acetylsalicylic acid, ASA)

Aspirin, introduced over 100 years ago, had been one of the most widely prescribed drugs because of its analgesic, antipyretic and anti-inflammatory properties for the management of mild pain and fever. However because of its side effects in children it lost its popularity to the more recent aspirin substitutes. Its predominant side effects are alterations in blood coagulation, gastric irritation and rarely, sensitivity reactions such as urticaria, angioneurotic edema, asthma and anaphylaxis. While many of these side effects are rare at low doses, alternative analgesics should be considered in certain situations. Prescription of aspirin postoperatively for surgical procedures where clotting is an issue, should be avoided. If gastric irritation is a cause for concern or there is a history of peptic ulcer, a buffered aspirin may be substituted or intake of food may be concurrently taken, although absorption of the drug may be compromised. Allergic type reactions occur more frequently in patients with pre-existing asthma, atopy and nasal polyps and aspirin should be avoided in these situations. With the association of aspirin with certain viral illnesses and the development of Reye syndrome it is recommended that aspirin be prescribed as the analgesic of last resort.

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 and Von Willebrands disease. Do not use in children under 16 years of age for viral infections (chickenpox or flu symptoms) with or without fever due to a potential association with Reyes syndrome. Should not be prescribed during pregnancy.

Warnings/Precautions: Use with caution in patients with platelet and bleeding disorders, renal dysfunction, dehydration, erosive gastritis, or peptic ulcer disease. Avoid use in severe renal failure or severe hepatic failure. Surgical patients should avoid aspirin if possible, for 1-2 weeks prior to surgery to reduce the risk of excessive bleeding.

Dosage:
Children: Analgesic and antipyretic: Oral, rectal: 10-15 mg/kg dose every 4-6 hours up to a total of 4 g/day
Adult: Analgesic and antipyretic: Oral, rectal: 325-650 mg every 4-6 hours up to 4g/day

Supplied as:
Tablets: 81 mg chewable, 325 mg, 500 mg tablets, caplets
Suppository, Rectal: 300 mg, 600 mg