Overview
Clopidogrel is an oral antiplatelet agent that inhibits platelet aggregation and reduces the risk of thrombotic cardiovascular events such as myocardial infarction, stroke, and vascular death. It is a prodrug that requires hepatic activation.
Mechanism of Action
Clopidogrel selectively and irreversibly inhibits the platelet P2Y12 ADP receptor. This prevents activation of the glycoprotein GPIIb/IIIa complex, thereby inhibiting platelet aggregation. Because platelet inhibition is irreversible, the effect lasts for the lifespan of the platelet (7–10 days).
Indications
- Recent myocardial infarction (MI)
- Recent ischemic stroke
- Established peripheral arterial disease
- Acute coronary syndrome (ACS) including unstable angina and NSTEMI
- ST-elevation myocardial infarction (STEMI) (with aspirin)
Dosage
Acute Coronary Syndrome (ACS): Loading dose: 300 mg (may use 600 mg in certain PCI settings) Maintenance dose: 75 mg once daily Recent MI, Stroke, or PAD: 75 mg once daily Can be taken with or without food.
Contraindications
- Active pathological bleeding (e.g., peptic ulcer, intracranial hemorrhage)
- Hypersensitivity to clopidogrel or any component of the formulation
Side Effects
- Bleeding
- Bruising
- Diarrhea
- Rash
- TTP (thrombocytopenia, microangiopathic hemolytic anemia, neurologic symptoms)
Interactions
- Strong CYP2C19 inhibitors (e.g., omeprazole, esomeprazole) may reduce effectiveness
- Anticoagulants (e.g., warfarin) increase bleeding risk
- NSAIDs increase gastrointestinal bleeding risk
- Aspirin (used intentionally in ACS but increases bleeding risk)
Counseling Points
- Bleeding risk. Monitor for bruising. Prescription only.