Antiplatelet / ACS Pregnancy: No clinical data in pregnancy; preferable not to use during pregnancy as a precautionary measure (animal studies show no direct harmful effects). Breast-feeding should not be continued during treatment.

Clopidogrel (ACS / Post-PCI)

Brand names: Plavix

Used in: Acute Coronary Syndrome & Chest Pain Stroke & TIA

Clopidogrel is an oral antiplatelet (a P2Y12 inhibitor) used in acute coronary syndromes, after percutaneous coronary intervention, and for secondary prevention after ischaemic stroke or in peripheral arterial 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, initiated with a 300 mg or 600 mg loading dose in acute coronary syndrome

Route: Oral

Frequency: once daily

Maintenance 75 mg once daily. Non-ST elevation ACS (unstable angina / non-Q-wave MI): 300 mg or 600 mg loading dose (600 mg may be considered when PCI is intended in patients <75 years), then 75 mg once daily with ASA 75–100 mg (support up to 12 months). ST elevation MI, medically treated / fibrinolysis-eligible: 300 mg loading (no loading dose if >75 years) then 75 mg once daily with ASA, for at least 4 weeks. Primary PCI or PCI >24 h after fibrinolysis: 600 mg loading (with caution if ≥75 years). PCI within 24 h of fibrinolysis: 300 mg loading; then 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 then 75 mg once daily plus ASA, started within 24 h and continued 21 days. Atrial fibrillation: 75 mg once daily with ASA 75–100 mg. Discontinue 7 days before elective surgery if antiplatelet effect is temporarily undesirable.

Dose adjustments

Renal

Therapeutic experience is limited in patients with renal impairment; no specific dose adjustment stated.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

Acute coronary syndrome ( 2.1 ) – Initiate clopidogrel tablets with a single 300 mg oral loading dose and then continue at 75 mg once daily. – Initiating clopidogrel tablets without a loading dose will delay establishment of an antiplatelet effect by several days. Recent MI, recent stroke, or established peripheral arterial disease: 75 mg once daily orally without a loading dose. ( 2.2 ) 2.1 Acute Coronary Syndrome In patients who need an antiplatelet effect within hours, initiate clopidogrel tablets with a single 300 mg oral loading dose and then continue at 75 mg once daily. Initiating clopidogrel tablets without a loading dose will delay establishment of an antiplatelet effect by several …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2024-05-17. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

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

Side effects

Bleeding — the most common reaction (including gastrointestinal and intracranial haemorrhage), mostly in the first month of treatment
Bruising / haematoma at bleeding sites
Thrombotic thrombocytopenic purpura (TTP) — very rare, potentially fatal
Acquired haemophilia — reported following use
(Note: the tabulated §4.8 list was truncated in the fetched label — verify full adverse-reaction table)

Interactions

Oral anticoagulants — concomitant administration not recommended (may increase intensity of bleeding)
ASA, heparin, glycoprotein IIb/IIIa inhibitors, NSAIDs (including COX-2 inhibitors), pentoxifylline — increased bleeding risk; use with caution
SSRIs and CYP2C19 strong inducers — increased bleeding risk
Triple antiplatelet therapy (clopidogrel + ASA + dipyridamole) — not recommended for stroke secondary prevention (increased haemorrhage)

Clinical monograph

How it works

Clopidogrel is a prodrug whose active metabolite irreversibly blocks the platelet P2Y12 ADP receptor, inhibiting platelet activation and aggregation for the platelet's lifespan.

Prescribing in practice

Often used with aspirin as dual antiplatelet therapy for a defined period after ACS/PCI, then continued as a single agent.
Stopping early after a coronary stent risks stent thrombosis — seek specialist advice before interrupting for surgery.
Activation depends on CYP2C19; effect is reduced in poor metabolisers and may be reduced by strong CYP2C19 inhibitors.
Bleeding risk is increased, especially with other antithrombotics or NSAIDs.

Monitoring

No routine monitoring of antiplatelet effect in standard practice; remain alert to bleeding.

Counselling the patient

Do not stop without advice, especially after a recent stent — stopping early can cause a clot.
Report bleeding or prolonged bruising.
Tell clinicians and dentists before procedures.

Evidence & guidelines

Dual antiplatelet therapy after ACS/PCI is guideline-directed; clopidogrel is also used for long-term secondary prevention where indicated.

Reference: CURE Trial (Yusuf et al. NEJM 2001); ESC NSTE-ACS 2020; ESC STEMI 2023; SPC Plavix; 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

Drugs

Aspirin (Antiplatelet — ACS/PCI) · Antiplatelet / ACS

Pathways