Antiplatelet agents · Cardiovascular
Clopidogrel
Plavix®(brand names vary by market)
A prodrug antiplatelet that some people cannot activate.
Mechanism
Its active metabolite irreversibly blocks the platelet P2Y12 ADP receptor for that platelet's lifetime, so recovery takes new platelets rather than drug clearance.
Indications
- Acute coronary syndrome and after coronary stenting
- Secondary prevention after ischemic stroke or myocardial infarction
- Peripheral arterial disease
- Aspirin intolerance
Formulations
Dosing concepts
Loading
A loading dose is used when the effect is needed within hours; without it, steady-state inhibition takes days.
Duration after a stent
The duration of dual antiplatelet therapy is set by the stent and the bleeding risk, and stopping early is a stent-thrombosis event, not a missed tablet.
Surgery
Held about five to seven days before major surgery, which is a platelet-turnover interval rather than a pharmacokinetic one.
Concepts, not prescribing instructions. Practice numbers live in current references and local protocols.
Pharmacokinetics
- Bioavailability
- ~50%
- Half-life
- Parent ~6 h; the platelet effect lasts the platelet's 7 to 10 day life
- Elimination
- hepatic: Two-step CYP activation, chiefly CYP2C19; poor metabolisers get substantially less effect
- Protein binding
- ~98%
Adverse effects
- Bleedingcommon & serious
- Bruisingcommon
- Diarrhoea and rashcommon
- Thrombotic thrombocytopenic purpuraseriousVery rare, usually within the first two weeks.
Contraindications & precautions
Contraindications
- Active pathological bleeding
- Severe hepatic impairment
Precautions
- Concurrent anticoagulation
- Upcoming surgery
- CYP2C19 poor metabolisers
- Concurrent omeprazole or esomeprazole
Interactions
Monitoring
Bleeding, overt and occult
The dose-limiting effect
Hemoglobin
Silent gastrointestinal loss
The planned stop date
Indefinite dual antiplatelet therapy is usually an oversight rather than a decision
Counselling points
- Do not stop this without speaking to your cardiologist, particularly in the months after a stent.
- Tell any dentist or surgeon before a procedure.
- Report black stools or prolonged bleeding.
- Ask before starting ibuprofen, naproxen, or a heartburn medicine.
Clinical pearls
- The omeprazole interaction is real but often over-applied: pantoprazole inhibits CYP2C19 far less and is the sensible pairing when a proton pump inhibitor is genuinely indicated.
- Clopidogrel plus aspirin plus an anticoagulant is triple therapy, and every extra day of it multiplies bleeding risk. Its duration should be explicit in the discharge summary.
References & review
- Clopidogrel product monograph (consult the current version for your market) (monograph)
- Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed. (reference-work)
Last reviewed 2026-08-16 · jurisdiction: global · drug information changes; verify against current references before practice use.