Adults

75 mg orally once daily. For Acute Coronary Syndrome: A single 300 mg or 600 mg oral loading dose may be given, followed by 75 mg once daily with aspirin.

Elderly

No dosage adjustment generally required for elderly patients. Use with caution if there are other risk factors for bleeding.

Renal_impairment

No dosage adjustment is necessary for patients with mild to moderate renal impairment. Use with caution in severe renal impairment.

Onset

Antiplatelet effect begins within 2 hours after a single dose; maximum effect achieved within 3-7 days of daily 75 mg administration.

Excretion

Approximately 50% via urine and 48% via feces, within 120 hours after a single dose.

Half life

Parent drug: approximately 8 hours. Active metabolite: approximately 30 minutes.

Absorption

Rapidly absorbed after oral administration. Bioavailability is about 50%. Peak plasma concentrations of the parent drug are reached within 45 minutes.

Metabolism

Extensively metabolized in the liver by CYP450 enzymes (primarily CYP2C19, CYP1A2, CYP2B6, CYP3A4) to an active thiol metabolite and inactive carboxylic acid derivatives.

NSAIDs (e.g., Ibuprofen, Naproxen)

Increased risk of gastrointestinal bleeding. Use with caution.

Oral Anticoagulants (e.g., Warfarin)

Increased risk of bleeding. Concomitant use is not recommended.

Other Antiplatelet Agents (e.g., Aspirin)

Increased risk of bleeding, but often used in combination for increased efficacy in specific indications (e.g., ACS).

Proton Pump Inhibitors (PPIs) (e.g., Omeprazole, Esomeprazole)

May reduce the antiplatelet effect of clopidogrel by inhibiting CYP2C19. Avoid concomitant use if possible; consider alternative PPIs or H2 blockers.