Anti-platelets - Aspirin

Question 1

what is aspirin used for

Answer 1

1) Acute coronary syndrome and acute ischaemic stroke
2) long term prevention of thrombotic arterial events in patients with cardiovascular, cerebrovascular and peripheral aterial disease.
3) to reduce the risk of intracardiac thrombus and embolic storke in atrial fibrillation (when warfarin can’t be used)
4) to control mild to moderate pain and fever

Question 2

how does aspirin work?

Answer 2

Aspirin irreversibly inhibits COX to reduce the production of the pro-aggregatory factor thromboxane from arachidonic acid —-> reduces platelet aggregation ——> less thrombus formation ——> reduces risk of arterial occlusion.

Question 3

When is the antiplatelet affect of aspirin most prominent?

Answer 3

low dose aspirin

Question 4

What are the side effects of aspirin?

Answer 4

• GI aspirin
• GI ulcer
• haemorrhage
• hypersensitivity (bronchospasm)
• tinnitus (regular high doses)

Question 5

what is the side effect of regular high doses of aspirin?

Answer 5

tinnitus

Question 6

Aspirin is life threatening in overdose - what are the features of aspirin overdose?

Answer 6

• hyperventilation
• hearing changes
• metabolic acidosis
• confusion
• convulsions
• cardiovascular collapse
• respiratory arrest

Question 7

What are the contraindications of aspirin?

Answer 7

• Dont give to children under 16yrs due to risk of Reye’s syndrome (affects liver and brain)
• don’t give if pt has had previous bronchospasm to aspirin or NSAID.
• 3rd trimester of pregnancy when prostaglandin inhibition may lead to premature closure of ductus arteriosus
• pepitc ulcers (give gastroprotection
• can trigger acute attack of gout

Question 8

What are the drug interactions of aspirin?

Answer 8

Caution is required with other antiplatelets due to increased risk of bleeding.

However frequently used with clopidogrel, dipyridamole (antiplatelets)
heparin, wafarin (anticoagulants)

Question 9

What is the loading dose and regular dose of aspirin for treatement of acute coronary syndrome?

Answer 9

• once only loading dose 300mg

- regular daily dose - 75mg

Question 10

What the prescription of aspirin for acute ischaemic stroke?

Answer 10

• 300 mg daily for 2 weeks

- then 75mg everyday

Question 11

What is the prescription of aspirin for long term prevention of thrombosis or in atrial fibrillation.

Answer 11

75mg daily

Question 12

Gastroprotection e.g. omeprazole 20mg should be considered for patients taking aspirin with increased risk of GI complications.
What are the risk factors?

Answer 12

• Age 65+
• previous peptic ulcer disease
• co-morbidities (cardiovascular disease, diabetes)
• drugs that have adverse GI effects e.g. NSAIDs and prednisolone