A 40-year-old female, Ms. Chloe Davis, comes to your pharmacy with a prescription for omeprazole 20 mg daily for heartburn. She also takes clopidogrel 75 mg daily for secondary prevention following a previous transient ischemic attack (TIA). What is the most appropriate action for the pharmacist to take?

Question: A 40-year-old female, Ms. Chloe Davis, comes to your pharmacy with a prescription for omeprazole 20 mg daily for heartburn. She also takes clopidogrel 75 mg daily for secondary prevention following a previous transient ischemic attack (TIA). What is the most appropriate action for the pharmacist to take?

Answer options:

• Dispense the omeprazole and counsel Ms. Davis to take it at a different time of day than clopidogrel. ✅ Contact the prescriber to recommend an alternative PPI, such as pantoprazole, or an H2-blocker.
• Dispense the omeprazole and advise Ms. Davis to monitor for signs of increased bleeding.
• Advise Ms. Davis that the omeprazole will likely improve the effectiveness of her clopidogrel due to reduced acidity.

Correct answer: Contact the prescriber to recommend an alternative PPI, such as pantoprazole, or an H2-blocker.

Explanation: Omeprazole is a strong inhibitor of CYP2C19, the enzyme responsible for converting clopidogrel to its active metabolite. This interaction can reduce the antiplatelet effect of clopidogrel, increasing the risk of cardiovascular events. Pantoprazole has minimal CYP2C19 inhibition, making it a safer alternative. H2-blockers are also an option as they do not significantly interact with clopidogrel.