Antiplatelet (P2Y12 ADP receptor antagonist) Pregnancy: Preferable not to use during pregnancy as a precautionary measure (no clinical exposure data). Breast-feeding: unknown whether excreted in human milk; as a precaution, breast-feeding should not be continued during treatment.

Clopidogrel

Brand names: Plavix

Clopidogrel is an oral thienopyridine antiplatelet used for secondary prevention of atherothrombotic events, in acute coronary syndromes, after stenting, and as an alternative to aspirin in occlusive vascular disease.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 75 mg once daily (maintenance)

Route: Oral

Frequency: Once daily (with or without food)

Adults and elderly. Non-ST segment elevation ACS (unstable angina / non-Q-wave MI): initiate with a single 300 mg or 600 mg loading dose, then continue 75 mg once daily with ASA 75-325 mg daily (ASA preferably not >100 mg); use up to 12 months. STEMI, medically treated eligible for thrombolytic/fibrinolytic therapy: 75 mg once daily initiated with a 300 mg loading dose with ASA (patients >75 years: initiate without loading dose); continue at least 4 weeks. PCI intended: 600 mg loading dose in primary PCI and PCI >24 h after fibrinolysis (patients >=75 years: give 600 mg LD with caution); 300 mg loading dose if PCI within 24 h of fibrinolysis; continue 75 mg once daily with ASA 75-100 mg up to 12 months. Moderate-to-high-risk TIA (ABCD2 >=4) or minor ischaemic stroke (NIHSS <=3): 300 mg loading dose then 75 mg once daily plus ASA 75-100 mg once daily, started within 24 h and continued for 21 days, then single antiplatelet therapy. Atrial fibrillation: 75 mg once daily with ASA 75-100 mg daily. 600 mg LD NOT recommended in NSTE-ACS patients >=75 years. Paediatric population: should not be used (efficacy concerns). Limited experience in renal and hepatic impairment.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or any excipient
Severe hepatic impairment
Active pathological bleeding such as peptic ulcer or intracranial haemorrhage

Side effects

Bleeding — most common adverse reaction (overall any-bleeding incidence 9.3% in CAPRIE)
Major bleeding (mostly gastrointestinal and at puncture sites) with ASA
Intracranial bleeding
Thrombotic thrombocytopenic purpura (TTP) — very rare
Acquired haemophilia

Interactions

Oral anticoagulants — concomitant use not recommended (may increase intensity of bleeding)
ASA, heparin, glycoprotein IIb/IIIa inhibitors, NSAIDs (incl. COX-2 inhibitors), SSRIs — increased bleeding risk
Triple antiplatelet therapy (clopidogrel + ASA + dipyridamole) — not recommended for stroke secondary prevention in acute non-cardioembolic ischaemic stroke/TIA (increased haemorrhage)
CYP2C19 strong inducers — caution (bleeding risk)
Pentoxifylline and other products associated with bleeding risk — caution

Clinical monograph

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.

Reference: NICE NG185; ESC ACS/NSTE Guidelines; POINT trial; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways