From the FDA Drug Label
Clopidogrel tablets may not work as well in people who: have certain genetic factors that affect how the body breaks down clopidogrel tablets.
- Clopidogrel tablets may not work as well in people who: take certain medicines, especially omeprazole (Prilosec ®) or esomeprazole (Nexium ®)
The failure of Plavix (clopidogrel) can occur due to several factors, including:
- Genetic factors: Certain genetic factors can affect how the body breaks down clopidogrel, leading to reduced efficacy.
- Drug interactions: Taking certain medicines, such as omeprazole or esomeprazole, can decrease the effectiveness of clopidogrel. It is essential to discuss these factors with your healthcare provider to determine the best course of treatment 1.
From the Research
Plavix (clopidogrel) failure should be managed by switching to alternative antiplatelet medications like ticagrelor (Brilinta) or prasugrel (Effient), as they don't require the same metabolic activation and have been shown to be effective in reducing ischemic events 2, 3. When Plavix failure is suspected, healthcare providers may recommend genetic testing or platelet function tests to confirm resistance. Key points to consider in managing Plavix failure include:
- Genetic variations in the CYP2C19 enzyme that metabolizes clopidogrel into its active form can reduce the medication's effectiveness 4
- Alternative antiplatelet medications like ticagrelor (Brilinta) or prasugrel (Effient) can be prescribed instead, as they don't require the same metabolic activation 2, 3
- These alternatives are typically dosed at 90mg twice daily for ticagrelor or 10mg daily for prasugrel (5mg daily for those over 75 or under 60kg) 5
- Patients experiencing symptoms like recurrent cardiovascular events while on Plavix should contact their healthcare provider immediately rather than discontinuing the medication on their own 6 The mechanism behind Plavix failure involves inadequate inhibition of the P2Y12 receptor on platelets, allowing continued platelet aggregation despite treatment. It's also important to note that certain patient populations, such as those with end-stage kidney disease, may not derive the same benefits from clopidogrel therapy and may be at increased risk of harm 4. In these cases, alternative antiplatelet agents like prasugrel or ticagrelor may be considered, and the use of platelet assays to tailor therapy may be beneficial 4.