Formulary
Clopidogrel: Uses, Dosing, Side Effects and Indian Brand Names
Clopidogrel is a thienopyridine prodrug that irreversibly inhibits platelet P2Y12 ADP receptors, essential for dual antiplatelet therapy after ACS and coronary stenting, with significant pharmacogenomic variability due to CYP2C19 polymorphisms.
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Clopidogrel: Uses, Dosing, Side Effects and Indian Brand Names
Clopidogrel is a thienopyridine prodrug that irreversibly inhibits platelet P2Y12 ADP receptors, essential for dual antiplatelet therapy after ACS and coronary stenting, with significant pharmacogenomic variability due to CYP2C19 polymorphisms.
NEET PG High-Yield: Prodrug requiring CYP2C19 activation -- pharmacogenomics is a favourite topic. CYP2C19 poor metabolisers (25-30% of South Asians) have reduced efficacy. Omeprazole interaction via CYP2C19. CURE trial. Irreversible P2Y12 inhibition (compare with ticagrelor which is reversible). Hold 5-7 days before surgery. TTP association (more common with ticlopidine). Prasugrel and ticagrelor are alternatives not dependent on CYP2C19.
Clinical overview
Clopidogrel is a second-generation thienopyridine antiplatelet agent that has become indispensable in modern cardiovascular practice, particularly as part of dual antiplatelet therapy (DAPT) with aspirin following acute coronary syndromes and percutaneous coronary intervention with stenting. The CURE trial demonstrated that adding clopidogrel to aspirin in non-ST elevation ACS reduced the composite endpoint of cardiovascular death, MI, and stroke by 20%. Being a prodrug, clopidogrel requires hepatic activation primarily through CYP2C19. This has major pharmacogenomic implications: approximately 25-30% of South Asians carry CYP2C19 loss-of-function alleles (*2 and *3), making them poor metabolisers with significantly reduced clopidogrel efficacy and increased risk of stent thrombosis. This is particularly relevant in Indian practice, where CYP2C19*2 allele frequency is among the highest globally. Prasugrel and ticagrelor are alternatives that are not dependent on CYP2C19 activation. The proton pump inhibitor omeprazole inhibits CYP2C19 and may reduce clopidogrel activation, though the clinical significance remains debated; pantoprazole has less CYP2C19 interaction and is preferred when gastroprotection is needed. Clopidogrel must be held 5-7 days before elective surgery to allow new platelet generation. In Indian practice, generic clopidogrel is highly affordable, and FDC tablets with aspirin are among the most prescribed cardiovascular combinations.
Pharmacological class
Clopidogrel belongs to the Antiplatelet Agents (Thienopyridine / P2Y12 Receptor Antagonist) class. Prodrug that is converted by hepatic CYP2C19 (primarily) and CYP3A4 to an active thiol metabolite, which irreversibly binds to and inhibits the P2Y12 subtype of ADP receptor on platelet surface. This prevents ADP-mediated activation of the glycoprotein IIb/IIIa complex, inhibiting platelet aggregation for the remaining platelet lifespan.
Indian brand names and formulations
Available as: Clopitab (Lupin), Clavix (Cipla), Deplatt (Torrent), Plavix (Sanofi).
Tablets: 75 mg, 300 mg (loading dose). Fixed-dose combinations with aspirin 75 mg (Clopitab-A, Deplatt-A, Clavix-AS) and with aspirin + atorvastatin.
Regulatory status
Clopidogrel is classified under Schedule H in India under the Drugs and Cosmetics Act, 1940. Prescription-only. Available on NLEM. Generic formulations widely accessible.
Indications
- Acute coronary syndrome (with aspirin as DAPT)
- Post-percutaneous coronary intervention with stenting (DAPT for 6-12 months)
- Recent myocardial infarction (secondary prevention)
- Recent ischaemic stroke or TIA
- Peripheral arterial disease
- Aspirin-intolerant patients requiring antiplatelet therapy
Dosing
ACS loading: 300-600 mg (600 mg preferred before PCI). Maintenance: 75 mg once daily. Duration of DAPT: typically 12 months after ACS, 6 months after elective PCI with drug-eluting stent. Stop 5-7 days before elective surgery.
Contraindications
- Active pathological bleeding (GI haemorrhage, intracranial haemorrhage)
- Severe hepatic impairment (impaired prodrug activation)
- Hypersensitivity to clopidogrel or other thienopyridines
Adverse effects
- Bleeding (most important -- GI, intracranial, at surgical sites)
- Bruising
- Dyspepsia and abdominal pain
- Diarrhoea
- Thrombotic thrombocytopenic purpura (TTP) -- rare but serious (less common than with ticlopidine)
- Rash
Drug interactions
- Omeprazole: inhibits CYP2C19, may reduce clopidogrel activation (prefer pantoprazole if PPI needed)
- Aspirin: additive bleeding risk, but this combination is standard in DAPT
- Warfarin: significantly increased bleeding risk; triple therapy (aspirin + clopidogrel + anticoagulant) kept as short as possible
- CYP2C19 inhibitors (fluconazole, fluvoxamine, fluoxetine): may reduce clopidogrel efficacy
Pregnancy and lactation
Category B. Limited human data. Use only if clearly needed. Generally avoided; aspirin alone is preferred for antiplatelet therapy in pregnancy when indicated.
Exam-style clinical scenario
A 48-year-old man undergoes PCI with a drug-eluting stent for STEMI. Despite standard dual antiplatelet therapy, he develops stent thrombosis at 2 weeks. CYP2C19 genotyping reveals he is a poor metaboliser (*2/*2). What change is appropriate? Switch from clopidogrel to prasugrel or ticagrelor, which are not dependent on CYP2C19 for activation.
Cost in India
Rs 30-80 for a strip of 10 tablets (75 mg). FDC with aspirin (Ecosprin Gold, Deplatt A) at Rs 50-100 per strip.
Clinical governance
Author: MedNext Editorial Team. Clinical reviewer: Awaiting clinical review. Jurisdiction: India (Drugs and Cosmetics Act, 1940). Sources: CIMS India, Indian Pharmacopoeia. Publication state: Awaiting clinical review. Correction: Report errors at support@mednext.academy.
Frequently Asked Questions
Why is the CYP2C19 polymorphism especially important in India?
Approximately 25-30% of South Asians carry CYP2C19 loss-of-function alleles (*2 and *3), making them intermediate or poor metabolisers. These patients generate less active metabolite, leading to inadequate platelet inhibition and a 2-3 fold increased risk of stent thrombosis. Pharmacogenomic testing before PCI is increasingly advocated but not yet standard practice in most Indian centres.
Why use pantoprazole instead of omeprazole with clopidogrel?
Omeprazole is a potent CYP2C19 inhibitor and may reduce conversion of clopidogrel to its active metabolite. Pantoprazole has minimal CYP2C19 inhibition and does not significantly affect clopidogrel activation. If a patient on clopidogrel needs a PPI for gastroprotection (which is common), pantoprazole is the preferred choice.
How does clopidogrel differ from ticagrelor?
Clopidogrel: prodrug (CYP2C19), irreversible P2Y12 inhibition, slower onset, affected by genetic polymorphisms, cheaper. Ticagrelor: active drug (no CYP activation needed), reversible P2Y12 inhibition, faster onset and offset, not affected by CYP2C19 variants, causes dyspnoea (adenosine reuptake inhibition), twice-daily dosing, more expensive. PLATO trial showed ticagrelor superior to clopidogrel in ACS.
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