Clopidogrel Resistance

Clopidogrel needs to be activated in the liver

The cytochrome 450 system is responsible for this activation

CYP2C19 is one of the key genes regulating the function of the cytochrome 450

Genetic variations of this CYP 2C19 gene have been identified

CYP 2C19*2 and CYP 2C 19*3 genetic variants are the two most common ones and haveĀ been found to be associated with a loss of function of the cytochrome 450 system

Importance Of Testing For Genetic Factors In Plavix Resistance

  • Once there is a loss of function of the cytochrome 450 system, clopidogrel cannot be converted to an active drug.
  • This can lead to a loss in protection against myocardial infarction or stroke in patients taking clopidogrel.
  • Up to 55% of Asians have these genetic variations, which can potentially result in adverse events in our local population.

Importance Of Testing For Genetic Factors In Plavix Resistance

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On March 12, 2010, the Federal Drug Administration of the US required a box warning for clopidogrel (Plavix, BMS and Sanofi Partnership) to caution that poor metabolizers of the drug may not receive full protection from myocardial infarction, stroke and cardiovascular deaths

The box warning also states that tests are available to determine the genetic profile of a key liver enzyme (CYP 2C19) and predict whether a patient will ineffectively convert clopidogrel to its active form

What Is Involved In The Genetic Test?

  • A 3ml EDTA blood sample
  • Buccal swab is an alternative