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Antiplatelet / ACS Pregnancy: Avoid if possible — limited data; use only if benefit outweighs risk with specialist advice

Clopidogrel (ACS / Post-PCI)

Brand names: Plavix

Adult dose

Dose: ACS loading: 300-600 mg once. Maintenance: 75 mg once daily (usually 12 months post-ACS/PCI, then assess).
Route: Oral
Frequency: Loading once, then 75 mg OD
Max: 600 mg loading; 75 mg/day maintenance
P2Y12 ADP receptor irreversible antagonist (prodrug — requires CYP2C19 activation). CURE trial established DAPT (aspirin + clopidogrel) for ACS. Preferred over ticagrelor/prasugrel in patients at high bleeding risk or taking anticoagulants (triple therapy).

Paediatric dose

Route: Oral
Seek specialist opinion — not licensed in children for cardiac indications

Dose adjustments

Renal

No dose adjustment required

Hepatic

Avoid in severe hepatic impairment (impaired prodrug activation + coagulopathy)

Clinical pearls

  • CURE trial (Yusuf et al. NEJM 2001): clopidogrel 300 mg load + 75 mg OD + aspirin vs aspirin alone in NSTEMI — 20% relative risk reduction in death, MI, or stroke. Established DAPT as standard of care.
  • CYP2C19 prodrug activation: clopidogrel is a prodrug requiring CYP2C19 to form active thiol metabolite. ~25-30% of patients are CYP2C19 poor metabolisers (particularly East Asian populations) — reduced antiplatelet effect. Genetic testing available; prasugrel/ticagrelor preferred in known poor metabolisers.
  • Omeprazole interaction: omeprazole inhibits CYP2C19, reducing clopidogrel activation by ~40%. The FDA issued a warning (2009). Use lansoprazole or pantoprazole as PPI cover with clopidogrel DAPT.
  • TTP risk: thrombotic thrombocytopenic purpura — typically within first 2 weeks of treatment. Presents as microangiopathic haemolytic anaemia + thrombocytopenia + fever + renal impairment + neurological symptoms. Stop immediately and treat with plasma exchange.
  • 600 mg loading dose: used in primary PCI for STEMI (preferred 600 mg over 300 mg for faster, more complete platelet inhibition). Ticagrelor and prasugrel achieve faster/greater platelet inhibition than even 600 mg clopidogrel.

Contraindications

  • Active pathological bleeding
  • Severe hepatic impairment
  • Hypersensitivity to clopidogrel

Side effects

  • Bleeding (GI, intracranial)
  • Rash/pruritus
  • TTP (thrombotic thrombocytopenic purpura — rare, within first 2 weeks)
  • GI upset
  • Dyspepsia

Interactions

  • Omeprazole/esomeprazole — inhibit CYP2C19 reducing clopidogrel activation by ~40%; use lansoprazole or pantoprazole instead with DAPT
  • Strong CYP2C19 inhibitors (fluoxetine, fluconazole, ciprofloxacin) — reduce antiplatelet effect
  • Aspirin — synergistic antiplatelet effect (CURE trial) + additive GI bleeding risk

Monitoring

  • Signs of bleeding
  • FBC (TTP monitoring — check at 1-2 weeks if symptomatic)
  • Platelet count

Reference: BNFc; BNF 90; CURE Trial (Yusuf et al. NEJM 2001); ESC NSTE-ACS 2020; ESC STEMI 2023; SPC Plavix. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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