20100519 - Ｑ　ｏｆ　Ｑ

1. Which of the following statements regarding limitations to the use of clopidogrel therapy is not correct?

Poor CYP3A4 metabolizer status is linked to decreased antiplatelet response

Approximately 3% of the general population does not appropriately metabolize clopidogrel

Poor metabolizers of clopidogrel may not receive full protection from myocardial infarction

Poor clopidogrel metabolizer status varies from 2% to 14% based on race

2. Which of the following statements regarding appropriate options for patients who are poor metabolizers of clopidogrel is correct?

Antiplatelet alternatives to clopidogrel are not recommended for poor metabolizers

Genetic tests have been approved to determine which patients are poor metabolizers

Appropriate dosing regimens have been established for poor metabolizers of clopidogrel

Increased loading and maintenance doses of clopidogrel may improve a patient's response

3. Which of the following statements regarding the use of clopidogrel in patients scheduled for invasive procedures in which an antiplatelet effect is not desired is not correct?

Withholding a single dose of clopidogrel is not effective for preventing a bleeding event during surgery

Stopping clopidogrel 3 days before surgery reduces the bleeding risk to that of aspirin alone

Platelet infusions for major bleeding must be timed according to the clopidogrel dosing schedule

Clopidogrel should be restarted as soon as possible after interruption of therapy

Which of the following statements regarding limitations to the use of clopidogrel therapy is not correct?
Answer: Poor CYP3A4 metabolizer status is linked to decreased antiplatelet response
Poor CYP2C19 metabolizer status is linked to a decreased antiplatelet response to clopidogrel and occurs in 3% of the general population, varying from 2% to 14% by race. Poor metabolizers of clopidogrel may not receive full protection from myocardial infarction, stroke, and cardiovascular death.

Which of the following statements regarding appropriate options for patients who are poor metabolizers of clopidogrel is correct?
Answer: Increased loading and maintenance doses of clopidogrel may improve a patient's response
Although an increase in clopidogrel loading and maintenance dosing is linked to an improved response in poor clopidogrel metabolizers, an appropriate regimen has not been established in clinical trials. Other antiplatelet drugs should also be considered. No genetic tests have been approved to determine metabolizer status, but off-label use of widely available genetic tests can identify the most common CYP2C19 alleles associated with poor clopidogrel metabolism.

Which of the following statements regarding the use of clopidogrel in patients scheduled for invasive procedures in which an antiplatelet effect is not desired is not correct?
Answer: Stopping clopidogrel 3 days before surgery reduces the bleeding risk to that of aspirin alone
Patients should discontinue clopidogrel 5 days before surgical procedures in which an antiplatelet effect is not desired, thereby decreasing the risk of major bleeding to that associated with use of aspirin alone. For patients who continue therapy and experience bleeding, platelets may be infused but not within 4 hours of a clopidogrel loading dose or within 2 hours of a maintenance dose. Treatment should be resumed as soon as possible to avoid the risk for cardiovascular events.

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