Irreversible COX Inhibitors Flashcards
Give an example of an irreversible COX inhibitor
Aspirin
What is the mechanism of action of aspirin?
- Irreversibly inhibits COX
- Irreversibly inhibits thromboxane A2
What is COX involved in?
Prostaglandin release
What is thromboxane A2 needed for?
Platelet aggregation
What is the result of the inhibition of thromboxane A2?
Prevents blood from clotting and forming thrombus
What is the route of delivery of aspirin?
PO
What are the indications for aspirin?
- Treatment of MI
- Prophylaxis of MI
- Pregnant women at high risk of pre-eclampsia
How is aspirin given in the treatment of MI?
Usually as 300mg stat dose
How is aspirin given in the prophylaxis of MI?
Usually 75mg OD
When is aspirin used in pregnant women at high risk of pre-eclampsia?
Can be taken from week 12 to delivery
What are the contraindications to aspirin?
- Patients on anti-platelet drugs, e.g. clopidogrel
- Patients at high risk of bleeding, e.g. haemophiliacs
- Peptic ulceration
- Known hypersensitivity to aspirin or NSAIDs
- Children under 16
Who should aspirin be used with caution in?
- Asthma
- Anaemia
- Elderly
- During 3rd trimester of pregnancy
What might aspirin interact with?
- NSAIDs
- Anticoagulants
- SSRIs
What are the side effects of aspirin?
- May induce bronchospasm in asthmatics
- Peptic ulceration
- GI bleeding
- Tinnitus
- Nasal polyps
What can be done to prevent peptic ulceration with aspirin?
PPI may be co-prescribed
When might the side effects of tinnitus and nasal polyps occur with aspirin?
At analgesic doses, which may be higher than dose used for secondary prevention of cardiac events
What counselling is required with aspirin?
- How to take aspirin
- Prolonged bleeding
- Not for children
How should aspirin be taken?
Non-dispersible aspirin should not be chewed. Should be swallowed whole with food, and indigestion remedies should be avoided at the time of aspirin consumption
What should the patient be told regarding prolonged bleeding?
Aspirin may cause a patient to bleed more or to bleed longer if they sustain an injury. Such symptoms should be reported to the patient’s GP
Why should aspirin not be given to children under 16?
Due to risk of causing Reye’s syndrome
