Clopidogrel: Test your drug IQ

Nursing, Oct 2002 by Gever, Marcy Portnoff

criticalcare

Find out how this drug is used to prevent myocardial infarction and stroke.

Clopidogrel bisulfate (Plavix) is a platelet aggregation inhibitor that prevents blood clot formation, which may be triggered by plaque breaking off from inside the arterial wall. Clopidogrel is prescribed to reduce the risk of myocardial infarction (MI) and stroke in patients with peripheral arterial disease or confirmed atherosclerosis, particularly those who've had a recent ischemic stroke or MI.

Results from the large, randomized CAPRIE (Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events) study suggest that clopidogrel is more effective than aspirin in reducing the risk of cardiovascular events and has a similar safety profile. The American College of Chest Physicians recommends that aspirin, which is less expensive, remain the drug of choice for most patients who require longterm antiplatelet therapy for coronary heart disease, as long as aspirin isn't contraindicated in those patients.

Clopidogrel and aspirin may provide a synergistic antithrombotic effect. The combination may be more effective than either drug used alone but must be used with caution because of the increased risk of bleeding.

Q. How is clopidogrel administered and what's the usual dosage?

A. Clopidogrel, available only as a 75-mg tablet, is administered orally with or without food. The recommended dosage for reducing the risk of fatal or nonfatal MI or stroke is 75 mg daily for all patients, including the elderly and patients with renal failure. The recommended initial dosage for the prevention of ischemic events in patients with unstable angina or non-Q-wave MI is 300 mg, followed by 75 mg daily, administered with 75 to 325 mg of aspirin daily

Q. What are the possible adverse reactions to clopidogrel?

A. Clopidogrel is generally as well tolerated as aspirin. Common adverse reactions to clopidogrel are gastrointestinal (GI) upset (abdominal pain, dyspepsia), chest pain, influenza-like symptoms, pain, fatigue, hypertension, headache, dizziness, and arthralgia.

Although rare, thrombotic thrombocytopenic purpura has occurred in some patients within 2 weeks of starting clopidogrel therapy.

Q. Who shouldn't take clopidogrel?

A. Clopidogrel is contraindicated in patients with an active bleeding condition, such as peptic ulcer or intracranial hemorrhage.

Q. Does clopidogrel interact with any other drugs?

A. Clopidogrel may potentiate the antithrombotic effects of aspirin and increase the risk of bleeding. When used concurrently with naproxen, clopidogrel may cause occult GI blood loss. Patients on clopidogrel also are at risk for bleeding if they take the drug concurrently with warfarin or heparin.

Q. What are some of the nursing considerations for a patient on clopidogrel?

A. Most of the nursing considerations focus on the bleeding risk posed by the drug. Tell your patient to:

* report any unusual bleeding or bruising.

* avoid taking any over-the-counter medications or herbal supplements without first speaking with her primary care provider (especially those that contain a nonsteroidal anti-inflammatory drug or aspirin, which can increase bleeding risk).

* inform her primary care provider if she's planning to have any medical procedures or major dental procedures, when significant bleeding is anticipated. (Clopidogrel should be stopped 7 days before surgery.)

SELECTED REFERENCES

Drug Facts and Comparisons. Facts and Comparisons, St. Louis, Mo., 2002.

Nursing2002 Drug Handbook. Springhouse Corp., Springhouse, Pa., 2002.

Physicians Desk Reference, 56th edition. Medical Economics Co., Inc., Montvale, N.J., 2002.

BY MARCY PORTNOFF GEVER, RPH, MED

Marcy Portnoff Gever is an independent pharmacist consultant and educator in Ringoes, NJ.