The interaction to report
The client takes clopidogrel and aspirin after a coronary stent placed 5 months ago, plus atorvastatin and omeprazole. Omeprazole and esomeprazole reduce the activation of clopidogrel, which can weaken its antiplatelet effect in a client with a recent stent. The nurse brings this combination to the prescriber's attention. When acid suppression is still needed with clopidogrel, pantoprazole is preferred.
Why omeprazole weakens clopidogrel
Clopidogrel is a prodrug: it has no antiplatelet effect until the liver converts it to its active form, mainly through the enzyme CYP2C19. Omeprazole and esomeprazole inhibit CYP2C19, so less active drug is formed and platelets are less inhibited. In a client with a coronary stent, reduced platelet inhibition raises the risk of stent thrombosis and heart attack. Pantoprazole has much less effect on CYP2C19 and is therefore preferred when a PPI is needed.
| Combination | Effect | Action |
|---|
| Omeprazole with clopidogrel | Reduced clopidogrel activation | Report; pantoprazole preferred |
| Aspirin with clopidogrel | Intended dual antiplatelet therapy after a stent | Continue as prescribed |
| Atorvastatin with clopidogrel | No clinically important effect at usual doses | Continue |
| Omeprazole with aspirin | PPI protects the stomach from aspirin | Helpful |
Why the other combinations are appropriate
Aspirin plus clopidogrel after a recent stent is dual antiplatelet therapy, intended to prevent stent thrombosis, and is continued for the period set by the cardiologist. Atorvastatin at usual doses has no clinically important effect on clopidogrel. A PPI given with aspirin protects the stomach from aspirin-related bleeding, which is a reason to keep acid suppression, just with a different PPI.
Watch out! Combining two antiplatelet drugs may look like a duplication error, but after a coronary stent it is deliberate. Do not report intended therapy as the problem.
Perioperative note
Because this client is preparing for fundoplication, his antiplatelet therapy also needs careful planning: stopping it early after a stent can cause stent thrombosis, so any change must be decided by the surgeon and cardiologist together. Key point! Omeprazole reduces activation of clopidogrel through CYP2C19; report the pairing, as pantoprazole is preferred when a PPI is needed with clopidogrel.