clopidogrel bisulfate
Plavix

Available forms
Available by prescription only
Tablets: 75 mg

Indications and dosages
 To reduce atherosclerotic events (MI, CVA, vascular death) in patients with atherosclerosis documented by recent CVA, MI, or peripheral arterial disease. Adults: 75 mg P.O. once daily with or without food.
 Patients with acute coronary syndrome (unstable angina and non-Q-wave MI), including those who are to be managed medically and those who are to be managed with percutaneous coronary intervention (with or without stent) or coronary artery bypass graft. Adults: Initially, 300 mg P.O. as a single loading dose, then 75 mg P.O. once daily with aspirin 75 to 325 mg P.O. once daily. Heparin may be used in the acute phase.

Pharmacodynamics
Antiplatelet action: Inhibits the binding of ADP to its platelet receptor and the subsequent ADP-mediated activation of glycoprotein IIb/IIIa complex, thereby inhibiting platelet aggregation. Because clopidogrel acts by irreversibly modifying the platelet ADP receptor, platelets exposed to the drug are affected for their life span.

Pharmacokinetics
Absorption: After repeated oral doses, plasma levels of parent compound, which has no platelet-inhibiting effect, are very low and generally below quantification limit. Pharmacokinetic evaluations are generally stated in terms of the main circulating metabolite. Rapidly absorbed after oral dosing. Following oral administration, about 50% of dose is absorbed.
Distribution: Clopidogrel and main circulating metabolite binds reversibly to human plasma proteins (98% and 94%, respectively).
Metabolism: Extensively metabolized by the liver. Main circulating metabolite is the carboxylic acid derivative that has no effect on platelet aggregation. It represents about 85% of circulating drug. Elimination half-life of main circulating metabolite is 8 hours.
Excretion: Following oral administration, about 50% is excreted in the urine and 46% in feces.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug or its components and in those with pathologic bleeding, such as peptic ulcer or intracranial hemorrhage.
  Use with caution in patients at risk for increased bleeding from trauma, surgery, or other pathologic conditions and in those with hepatic impairment or severe hepatic disease.

Interactions
Drug-drug. Aspirin, NSAIDs: May increase risk of GI bleeding. Use together cautiously.
Heparin, warfarin: Safety hasn’t been established. Use together cautiously.
Drug-herb. Red clover: May cause increased bleeding. Discourage use together.

Adverse reactions
CNS: asthenia, depression, dizziness, fatigue, headache, paresthesia, syncope, pain.
CV: chest pain, edema, hypertension, palpitations.
EENT: epistaxis, rhinitis.
GI: abdominal pain, constipation, diarrhea, dyspepsia, gastritis, hemorrhage, nausea, vomiting.
GU: urinary tract infection.
Hematologic: purpura.
Musculoskeletal: arthralgia.
Respiratory: bronchitis, cough, dyspnea, upper respiratory tract infection.
Skin: rash, pruritus.
Other: flulike symptoms.

Effects on lab test results
• May decrease platelet count.

Overdose and treatment
No adverse effects were reported after single oral administration of 600 mg (equivalent to eight standard 75-mg tablets). The bleeding time was prolonged by a factor of 1.7, which is similar to that observed with the therapeutic dosage of 75 mg daily.
 Based on biological plausibility, platelet transfusion may be appropriate to reverse the pharmacologic effects of clopidogrel if quick reversal is required.

Special considerations
• Drug is usually used in patients who are hypersensitive or intolerant to aspirin.
• If patient is to undergo surgery and an antiplatelet effect isn’t desired, drug should be stopped 7 days before surgery.
• Monitor patient for unusual bleeding or bruising.
 ALERT Don’t confuse Plavix (clopidogrel) with Paxil (paroxetine).
Breast-feeding patients
• It isn’t known if drug or its metabolites appear in breast milk. Assess risks and benefits before continuing drug in breast-feeding women.
Pediatric patients
• Safety and efficacy in children haven’t been established.

Patient education
• Inform patient that it may take longer than usual to stop bleeding; therefore, advise him to refrain from activities in which trauma and bleeding may occur. Encourage use of seat belts.
• Tell patient to inform medical personnel of clopidogrel use before scheduling surgery or taking new drugs.
• Inform patient that drug may be taken without regard to meals.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use