Clopidogrel

How it works

It is a prodrug whose active metabolite irreversibly blocks the platelet P2Y12 ADP receptor, inhibiting ADP-mediated platelet activation and aggregation for the platelet's lifespan.

Prescribing in practice

• The principal hazard is bleeding, so it should be stopped a number of days before elective surgery where appropriate and used cautiously with other antithrombotics or NSAIDs.
• Activation depends on CYP2C19, so concomitant strong inhibitors such as omeprazole and esomeprazole may reduce its antiplatelet effect.
• Use with caution in those at high bleeding risk and in significant hepatic impairment.

Monitoring

Routine platelet-function monitoring is not required; instead review clinically for bruising and bleeding and confirm the planned duration of dual antiplatelet therapy.

Counselling the patient

• Do not stop without advice, particularly after a recent stent.
• Report unusual bruising, black stools or prolonged bleeding.
• Tell any dentist or surgeon that you take clopidogrel.

Evidence & guidelines

Landmark trials including CAPRIE and CURE established clopidogrel's benefit in vascular secondary prevention and acute coronary syndromes, informing NICE antiplatelet guidance.