Aspirin

Question 1

Mechanism of action ?

Answer 1

Platelet-rich thrombus forms in atheromatous arteries and occludes circulation causing thrombotic events.
Aspirin irreversibly inhibits COX to reduce production of the pro-aggregatory factor thromboxane from arachidonic acid, which reduces platelet aggregation reduces the risk of arteries occlusion. Aspirin is able to inhibit platelet aggreration at low doses with a lasting effect until new platelets are formed. 300mg &below.

Question 2

Indications ?

Answer 2

• acute coronary syndrome and acute ischemic stroke, where rapid inhibition of latelet-aggregation can prevent/limit arteries clogging due to thrombosis, reducing by that subsequent mortality.
• long term secondary prevention of thrombotic arterial events in patients with cardiovascular, cerebrovascular &arterial diseases.
• in atrial fibrillation AF to reduce risk of intracardiac thrombus &embolic stroke, where warfarin &novel oral anticoagulants are CIed.
• mild to moderate pain &fever, although other drugs are usually preferred, especially in inflammatory profiles.

Question 3

Important AE ?

Answer 3

• gastrointestinal irritation, more seriously, gastrointestinal ulceration &hemorrhage. Aside to hypersensitivity reactions such as bronchospasm.
• in regular high-dose therapy : tinnutis (des acouphenes).
• in overdose, aspirin is life threatening : hyperventilation, hearing changes, metabolic acidosis &confusion, followed by convulsions, cardiovascular collapse &respiratory arrest.

Question 4

Important cautions ?

Answer 4

• Aspirin should be avoided in children under 16 due to risk of Reye’s syndrome.
• Aspirin is not to be administered to people with aspirin hypersentitivity; who have had bronchospasm or other allergic symptoms triggered by exposure to aspirin or to NSAIDs (like your father).
• Aspirin should be avoided in the third trimester of pregnancy when PG inhibition may lead to premature closure of the ductus arteriosus.
• Aspirin must be used with caution in patients with peptic ulceration or gout.

Question 5

How is aspirin taken ?

Answer 5

oral or rectal route (higher doses) administration, after food to minimise gastric irritation. enteric-coated tablets may help but are inefficient when needing rapid pain relief or in medical emergencies due to slower absorption.

• in acute coronary syndrome, prescribe aspirin in an initial &unique dose of 300mg followed by regular daily dose of 75mg.
• acute ischemic stroke, prescribe aspirin 300 mg daily for 2wks before switching to the 75mg.
• long term thrombosis prevention in people with AF : low-dose aspirin 75mg.
• higher doses are givev to control pain &fever, with a max of 4g taken in divided doses.

Question 6

gastroprotection ?

Answer 6

-gastroprotection should be considered for patients taking low-doses of aspirin &presenting risk factors : age above 65, previous peptic ulcer disease or comorbidities &concurrent therapy with other drugs inducing gastrointestinal AE, particularly NSAIDs &prednisolone.