Adults

For established atherothrombotic disease: 75 mg once daily. For acute coronary syndrome (unstable angina or NSTEMI): initial loading dose of 300 mg or 600 mg, followed by 75 mg once daily with aspirin. For STEMI: 75 mg once daily with aspirin, with or without a loading dose.

Elderly

No dosage adjustment generally required for elderly patients.

Renal_impairment

No dosage adjustment generally required for mild to moderate renal impairment. Caution advised in severe impairment due to limited experience.

Onset

Onset of antiplatelet effect within 2 hours; maximal effect within 3-7 days of daily dosing.

Excretion

Approximately 50% excreted in urine and 48% in feces over 120 hours. Less than 1% is excreted unchanged.

Half life

Approximately 8 hours for the active metabolite. The parent compound has a half-life of about 6 hours.

Absorption

Rapidly absorbed after oral administration. Bioavailability is approximately 50%. Peak plasma concentrations of the active metabolite occur about 30-60 minutes after dosing.

Metabolism

Extensively metabolized in the liver by CYP450 enzymes (primarily CYP2C19 and CYP3A4) into an active thiol metabolite and an inactive carboxylic acid derivative.

SSRIs and SNRIs

Increased risk of bleeding.

NSAIDs (e.g., ibuprofen, naproxen)

Increased risk of gastrointestinal bleeding. Use with caution.

Warfarin and other oral anticoagulants

Increased risk of bleeding. Co-administration is not recommended.

Proton Pump Inhibitors (PPIs) (e.g., omeprazole, esomeprazole)

May reduce clopidogrel's antiplatelet effect due to CYP2C19 inhibition. Avoid concomitant use, especially in ACS patients. Consider alternative PPIs or H2 blockers.