indication

For the reduction of atherosclerotic events (myocardial infarction, stroke, and vascular death) in patients with atherosclerosis documented by recent stroke, recent myocardial infarction, or established peripheral arterial disease

pharmacology

Clopidogrel, an antiplatelet agent structurally and pharmacologically similar to ticlopidine, is used to reduce atherosclerotic events such as myocardial infarction, stroke, and vascular death in patients who have had a recent stroke, recent MI, or have established peripheral vascular disease.

mechanism of action

The active metabolite of clopidogrel prevents binding of adenosine diphosphate (ADP) to its platelet receptor, impairing the ADP-mediated activation of the glycoprotein GPIIb/IIIa complex. It is proposed that the inhibition involves a defect in the mobilization from the storage sites of the platelet granules to the outer membrane. he drug specifically and irreversibly inhibits the P2Y12 subtype of ADP receptor, which is important in aggregation of platelets and cross-linking by the protein fibrin. No direct interference occurs with the GPIIb/IIIa receptor. As the glycoprotein GPIIb/IIIa complex is the major receptor for fibrinogen, its impaired activation prevents fibrinogen binding to platelets and inhibits platelet aggregation. By blocking the amplification of platelet activation by released ADP, platelet aggregation induced by agonists other than ADP is also inhibited by the active metabolite of clopidogrel.

toxicity

Symptoms of acute toxicity include vomiting (in baboons), prostration, difficult breathing, and gastrointestinal hemorrhage.

biotransformation

Hepatic, extensive and rapid, by hydrolysis to the main circulating metabolite, a carboxylic acid derivative, which accounts for approximately 85% of the circulating drug-related compounds. A glucuronic acid derivative of the carboxylic acid derivative has also been found in plasma and urine. Neither the parent compound nor the carboxylic acid derivative has a platelet inhibiting effect.

absorption

Absorption is at least 50% based on urinary excretion of clopidogrel-related metabolites. Bioavailability has not been found to be affected by food.

half life

Carboxylic acid derivative: 8 hours (after single and multiple doses). Covalent binding to platelets has accounted for 2% of radiolabeled clopidogrel with a half-life of 11 days.

route of elimination

Following an oral dose of 14C-labeled clopidogrel in humans, approximately 50% of total radioactivity was excreted in urine and approximately 46% in feces over the 5 days post-dosing.

drug interactions

Bortezomib: Moderate CYP2C19 Inhibitors like bortezomib may decrease serum concentrations of the active metabolite(s) of Clopidogrel. Avoid concurrent use of moderate CYP2C19 inhibitors with clopidogrel whenever possible. If such a combination must be used, monitor closely for evidence of reduced clinical response to clopidogrel.

Drotrecogin alfa: Antiplatelet agents such as clopidogrel may enhance the adverse/toxic effect of Drotrecogin Alfa. Bleeding may occur. Increase monitoring for signs/symptoms of bleeding during concomitant therapy. If possible, avoid use of drotrecogin within 7 days of use of any IIb/IIIa antagonists, higher dose aspirin (more than 650 mg/day), or use of other antiplatelet agents.

Esomeprazole: Esomeprazole may decrease serum concentrations of the active metabolite(s) of clopidogrel. Due to the possible risk for impaired clopidogrel effectiveness with this combination, clinicians should carefully consider the need for concurrent esomeprazole therapy in patients receiving clopidogrel. Monitor response to clopidogrel closely when using clopidogrel with esomeprazole. Whether there are differences among individual proton pump inhibitors is unclear. Other acid-lowering therapies (e.g., H2-receptor antagonists, antacids, etc.) do not appear to share this interaction with clopidogrel.

Ginkgo biloba: Additive anticoagulant/antiplatelet effects may increase bleed risk. Concomitant therapy should be avoided.

Lansoprazole: Lansoprazole may decrease serum concentrations of the active metabolite(s) of clopidogrel. Due to the possible risk for impaired clopidogrel effectiveness with this combination, clinicians should carefully consider the need for concurrent lansoprazole therapy in patients receiving clopidogrel. Monitor response to clopidogrel closely when using clopidogrel with lansoprazole. Whether there are differences among individual proton pump inhibitors is unclear. Other acid-lowering therapies (e.g., H2-receptor antagonists, antacids, etc.) do not appear to share this interaction with clopidogrel.

Omeprazole: Omeprazole may decrease serum concentrations of the active metabolite(s) of clopidogrel. Clopidogrel prescribing information recommends avoiding concurrent use with omeprazole, due to the possibility that combined use may result in decreased clopidogrel effectiveness.

Pantoprazole: Pantoprazole may decrease serum concentrations of the active metabolite(s) of clopidogrel. Due to the possible risk for impaired clopidogrel effectiveness with this combination, clinicians should carefully consider the need for concurrent pantoprazole therapy in patients receiving clopidogrel. Monitor response to clopidogrel closely when using clopidogrel with pantoprazole. Whether there are differences among individual proton pump inhibitors is unclear. Other acid-lowering therapies (e.g., H2-receptor antagonists, antacids, etc.) do not appear to share this interaction with clopidogrel.

Rabeprazole: Rabeprazole may decrease serum concentrations of the active metabolite(s) of clopidogrel. Due to the possible risk for impaired clopidogrel effectiveness with this combination, clinicians should carefully consider the need for concurrent rabeprazole therapy in patients receiving clopidogrel. Monitor response to clopidogrel closely when using clopidogrel with rabeprazole. Whether there are differences among individual proton pump inhibitors is unclear. Other acid-lowering therapies (e.g., H2-receptor antagonists, antacids, etc.) do not appear to share this interaction with clopidogrel.

Rivaroxaban: Antiplatelet agents such as clopidogrel may enhance the anticoagulant effect of rivaroxaban. Avoid concurrent use of clopidogrel with rivaroxaban unless the anticipated benefits outweigh the risks of bleeding. Canadian rivaroxaban labeling recommends avoiding concurrent use with any antiplatelet agent, while the U.S. rivaroxaban labeling recommends caution and increased monitoring if used with any other antiplatelet agent. Any combined use should only be undertaken with increased monitoring for evidence of bleeding.

Treprostinil: The prostacyclin analogue, Treprostinil, increases the risk of bleeding when combined with the antiplatelet agent, Clopidogrel. Monitor for increased bleeding during concomitant thearpy.

Warfarin: Increased bleed risk may occur as a result of additive anticoagulant effects. Increase monitoring for signs and symptoms of bleeding during concomitant therapy.