In a patient taking clopidogrel and omeprazole, which factor is most likely to contribute to a myocardial infarction?

The correct response highlights a significant drug interaction between clopidogrel and omeprazole that can lead to adverse cardiovascular events such as myocardial infarction. Clopidogrel is an antiplatelet medication that requires metabolic activation to become effective. It is primarily activated by the cytochrome P450 enzyme system, specifically CYP2C19.

Omeprazole, a proton pump inhibitor, is known to inhibit CYP2C19. When it is administered concurrently with clopidogrel, it can reduce the conversion of clopidogrel into its active form. As a result, this leads to diminished antiplatelet effects, increasing the risk of thrombotic events, including myocardial infarction.

This interaction is clinically significant because patients on clopidogrel who also require a proton pump inhibitor for gastrointestinal protection may be inadvertently increasing their cardiovascular risk if the proton pump inhibitor affects their anticoagulant therapy. Therefore, the reduced antiplatelet activity of clopidogrel due to omeprazole is critical in understanding how this drug combination may lead to myocardial infarction in susceptible individuals.