Pharm 101: Clopidogrel

Class

Antiplatelet

Pharmacodynamics

• Thienopyridine
• Reduce platelet aggregation by inhibiting ADP pathway of platelets
• Irreversibly inhibits ADP P2Y12 receptor on platelets for life of platelet
• Unlike aspirin, no effect on prostaglandin metabolism

Pharmacokinetics

• Prodrug
• Hepatic metabolism to active and inactive metabolites
• 80% of platelet activity inhibited within five hours of loading dose of 300mg
• Effects lasts for life of platelet, duration of anti-platelet effect 7-10 days
• Elimination half-life 30-60 minutes
• Following oral dose, 50% excreted in urine and 46% in faeces in next five days

Clinical uses

• Ischaemic heart disease including NSTEMI, STEMI, pre/post stent
• Peripheral vascular disease
• Stroke prevention
• Dosage 75mg daily, or 300-600mg loading dose

Adverse effects

• Gastrointestinal upset
• Bleeding
• Thrombotic thrombocytopenic purpura

Further Reading

• Nickson C. STEMI Management
• Jayasinghe R, Markham R, Adsett G. Dual antiplatelet therapy