Clopidogrel

Antiplatelet agents

ATC code: B01AC04 (Clopidogrel)

Mechanism of action

Prodrug. Its active metabolite irreversibly blocks P2Y12 ADP receptors on platelet membranes, suppressing ADP-dependent activation of the GPIIb/IIIa complex and platelet aggregation. The effect persists for the platelet's lifespan. Activation via CYP2C19 means carriers of loss-of-function alleles (*2, *3) have reduced antiplatelet effect.

Indications

Established ASCVD, secondary prevention

First line

Clopidogrel plus aspirin (DAPT) is the standard after acute coronary syndrome and percutaneous coronary intervention. The CURE trial showed a 20 % reduction in the composite of vascular death, MI, and stroke. DAPT duration is 6–12 months depending on stent type and bleeding risk. Clopidogrel monotherapy is an alternative when aspirin is not tolerated.

After ACS, given as part of dual antiplatelet therapy (DAPT) with aspirin for 6–12 months.

Ischemic stroke

First line

Clopidogrel is one of the antiplatelet options for secondary prevention of ischemic stroke. The CAPRIE trial demonstrated a small but statistically significant advantage of clopidogrel over aspirin in preventing ischemic events. Dose is 75 mg once daily long-term.

Peripheral artery disease

First line

In peripheral artery disease, clopidogrel is the preferred antiplatelet agent. Subgroup analyses from CAPRIE showed a particularly pronounced advantage over aspirin in this population. Dose is 75 mg daily.

Practical notes

Timing and administration

Take once daily with or without food. In ACS, a loading dose of 300 mg (or 600 mg before PCI) is given in hospital. Maintenance dose is 75 mg daily. Full antiplatelet effect develops in 3–7 days of regular use without a loading dose.

Special situations

Pharmacogenetics: 2–14 % of Europeans are CYP2C19 poor metabolizers (*2/*2 or *2/*3) with reduced clopidogrel effect. FDA recommends considering genotyping in high-risk patients. Alternatives include ticagrelor or prasugrel (not dependent on CYP2C19). Concurrent omeprazole attenuates clopidogrel activation. Pantoprazole or rabeprazole are preferred PPIs.

Safety

Contraindications

Active bleeding (GI, intracranial)
Severe hepatic impairment
Hypersensitivity to clopidogrel

Serious adverse effects

Major bleeding (GI, intracranial)
Thrombotic thrombocytopenic purpura – TTP (very rare but life-threatening)
Neutropenia, agranulocytosis (very rare)

Common adverse effects

Bleeding (ecchymoses, epistaxis, gingival bleeding)
Dyspepsia, diarrhea
Headache

PregnancyFDA B

FDA category B. Limited human data in pregnancy. Prescribed only when benefit clearly outweighs potential risk.

Breastfeeding

No data on excretion in breast milk. Decision is individualized.