A “poor metabolizer” does not effectively convert Plavix to its active form because of low CYP 2C19 activity.

How does someone figure out they are a “poor metabolizer”?

Read the FDA communication if you’re seriously interested in the answer to this question.

FDA Drug Safety Communication: Reduced effectiveness of Plavix (clopidogrel) in patients who are poor metabolizers of the drug

The U.S. Food and Drug Administration (FDA) has added a Boxed Warning to the label for Plavix, the anti-blood clotting medication. The Boxed Warning is about patients who do not effectively metabolize the drug (i.e. “poor metabolizers”) and therefore may not receive the full benefits of the drug.