Antiplatelets (clopidogrel)

Question 1

What is the method of action of clopidogrel?

Answer 1

• Activated by CYP450 enzymes
• Irreversibly inhibits the adenosine diphosphate receptor P2Y12 on the platelet surface from binding to ADP (signal for platelet aggregation)
• Glycoprotein GPIIb/IIIa complex is not activated = no platelet aggregation

Question 2

What are the indications for clopidogrel?

Answer 2

• Treatment of acute coronary syndrome
• Prevent occlusion of coronary artery stents
• Secondary prevention of thrombotic arterial event – for those with cardiovascular, cerebrovascular and peripheral arterial disease
• Reduce risk of intercardiac thrombus and embolic stroke in AF

Question 3

What are the contraindications for clopidogrel?

Answer 3

• Active bleeding
• 7 days before elective surgery – should be stopped
• Renal impairment
• Hepatic impairment

Question 4

What are the side effects of clopidogrel?

Answer 4

• Bleeding
• GI upset – dyspepsia, abdominal pain, diarrhea
• Thrombocytopenia

Question 5

What are the interactions with clopidogrel?

Answer 5

• Cytochrome P450 inhibitors – reduce efficacy e.g.
• Omeprazole
• Ciprofloxacin
• Erythromycin
• Antifugals
• SSRIs
• Other antiplatelets i.e. aspirin
• Anticoagulants i.e. heparin
• NSAIDs – increased risk of bleeding

Question 6

Which organ eliminates clopidogrel?

Answer 6

• Kidney

* Faeces

Question 7

What patient information should be given to patients on clopidogrel?

Answer 7

• Continuation of treatment is essential

* Stopping bleeding will take longer than expected